Chapter: Chemical reactions and equations
Top definitions:
1. Chemical reaction: A chemical reaction involves a chemical change in which substances react to form new substances with entirely new properties. Substances that react or take part in the reaction are
known as reactants and the substances formed are known as products. 2. Physical change: If a change involves change in colour or state but no
new substance is formed, then it is a physical change.
3. Chemical change: If a change involves formation of new substances, it is a chemical change.
4. Chemical equation: The symbolic representation of a chemical reaction is called a chemical equation.
5. Exothermic and endothermic reactions: If heat is evolved during a reaction, then such a reaction is known as exothermic reaction. If heat is absorbed from the surroundings, then such a reaction is known as endothermic reaction
6. Combination reaction: Combination reaction is a reaction in which 2 or more substances combine to give a single product.
7. Decomposition reaction: In a decomposition reaction, a single reactant decomposes to give 2 or more products. Decomposition reactions require energy in the form of heat, light or electricity
8. Displacement reaction: A reaction in which a more active element displaces less active element from its salt solution.
9. Reactivity series: The Reactivity series is a list of metals arranged in the order of decreasing reactivity. The most reactive metal is placed at the top and the least reactive metal is placed at the bottom.
10.Double displacement reaction: A chemical reaction in which there is an exchange of ions between the reactants to give new substances is called a double displacement reaction.
11.Precipitation reaction: An insoluble solid known as precipitate is
formed during a double displacement reaction. Such reactions are also known as precipitation reactions.
12.Redox reaction: A reaction, in which oxidation and reduction takes place simultaneously is known as redox reaction.
13.Oxidation: Oxidation is a chemical process in which a substance gains oxygen or loses hydrogen.
14.Reduction: Reduction is a chemical process in which a substance gains hydrogen or loses oxygen.
Key learnings:
1. A chemical reaction involves a chemical change in which substances react to form new substances with entirely new properties.
Substances that react or take part in the reaction are known as reactants and the substances formed are known as products. 2. During a chemical reaction, there is a breaking of bonds between
atoms of the reacting molecules to give products.
3. A chemical reaction can be observed with the help of any of the following observations: a) Evolution of a gas b) Change in temperature c) Formation of a precipitate d) Change in colour e) Change of state
4. Physical change: If a change involves change in colour or state but no new substance is formed, then it is a physical change.
5. Chemical change: If a change involves formation of new substances, it is a chemical change.
6. Exothermic and endothermic reactions: If heat is evolved during a reaction, then such a reaction is known as Exothermic reaction. If heat is absorbed from the surroundings, then such a reaction is known as endothermic reaction.
7. Chemical equation: The symbolic representation of a chemical reaction is called a chemical equation.
8. Features of a chemical equation:
a. The reactants are written on the left hand side with a plus sign between them.
b. The products are written on the right hand side with a plus sign between them.
c. An arrow separates the reactants from the products. The arrow head points towards the products and indicates the direction of the reaction.
9. Skeletal chemical equation: A chemical equation which simply represents the symbols and formulae of reactants and products taking part in the reaction is known as skeletal chemical equation for a reaction. For example: For the burning of Magnesium in the air, Mg + O2 → MgO is the skeletal equation.
10. Balanced chemical equation: A balanced equation is a chemical equation in which number of atoms of each element is equal on both sides of the equation i.e. number of atoms of an element on reactant side = number of atoms of that element on the product side.
11. As per the law of conservation of mass, the total mass of the elements present in the products of a chemical reaction is equal to the total mass of the elements present in the reactants.
12. The process of equating the number of atoms on both the sides of a chemical equation is known as balancing of a chemical equation.
a. The first step in balancing a chemical equation is to write the number of atoms of each element present on the left hand side and right hand side.
b. We should always start balancing with the compound that contains maximum number of atoms. It can be reactant or a product. Then in that compound select the element which has the maximum number of atoms.
c. While balancing a chemical equation, the molecular formulae of the reactants and products should not change. The
molecular formulae are simply multiplied by suitable coefficients.
d. To make a chemical equation more informative, the reaction conditions such as temperature, pressure or catalyst are written on the arrow separating the reactants and products. e. The evolution of gas is indicated by an upward arrow. f. The formation of precipitate is indicated by a downward
arrow.
g. Heat evolved during the reaction is written as + Heat on the product side.
h. Heat absorbed during the reaction is written as + Heat on the reactant side.
13.Types of chemical reactions: a. Combination reaction b. Decomposition reaction c. Displacement reaction d. Redox reaction
14.Combination reaction is a reaction in which 2 or more substances combine to give a single product. Combination reaction can be between 2 elements, between an element and a compound or between 2 compounds.
15.Decomposition reaction: In a decomposition reaction, a single reactant decomposes to give 2 or more products. Decomposition reactions require energy in the form of heat, light or electricity
16.Types of decomposition reactions:
a. Decomposition reactions which require heat are known as thermolytic decomposition reactions
b. Decomposition reactions which require light are known as photolytic decomposition reactions
c. Decomposition reactions which require electricity are known as electrolytic decomposition reactions
17.Displacement reaction: A reaction in which a more active element displaces less active element from its salt solution.
18.The reactivity series is a list of metals arranged in the order of decreasing reactivity. The most reactive metal is placed at the top and the least reactive metal is placed at the bottom.
19.Double displacement reaction: A chemical reaction in which there is an exchange of ions between the reactants to give new
substances is called double displacement reaction.
20.Precipitation reaction: An insoluble solid known as precipitate is formed during a double displacement reaction. Such reactions are also known as precipitation reactions.
21.Redox reaction: A reaction in which oxidation and reduction take place simultaneously in a reaction, is known as a redox reaction. 22.Oxidation is a chemical process in which a substance gains oxygen
or loses hydrogen.
23.Reduction is a chemical process in which a substance gains hydrogen or loses oxygen.
24.If a substance gains oxygen or loses hydrogen during a reaction, it is said to be oxidised.
25.If a substance gains hydrogen or loses oxygen during a reaction, it is said to be reduced.
26.A substance that loses oxygen or gains hydrogen is known as an oxidising agent.
27.A substance that loses hydrogen or gains oxygen is known as a reducing agent.
28.An oxidising agent gets reduced whereas a reducing agent gets oxidised.
29. In terms of electronic concept, Oxidation is defined as a loss of electrons while reduction is defined as a gain of electrons.
30. Corrosion is the slow eating up of metals by the action of air and moisture on their surfaces. Corrosion in case of Iron is known as Rusting.
31.Chemically, rust is hydrated ferric oxide (Fe2O3.xH2O)
32.Advantages of corrosion: Though corrosion is undesirable, it can be advantageous in case of aluminium which on exposure to air, gets coated with a protective layer of aluminium oxide. This
33.Rancidity: When oils and fats or foods containing oils and fats are exposed to air, they get oxidised due to which the food becomes stale and gives a bad taste or smell. This is called Rancidity. 34. Rancidity can be prevented by:
a) Adding antioxidants i.e. the substances which prevent oxidation b) Refrigeration
Chapter : Acids, Bases and Salts
Top concepts:
1. Definition of acids , bases and salts:
Acids Bases Salts
Sour in taste Bitter in taste & soapy to touch
Acid + Base → Salt + Water Give H+ or H3O+ ions in aqueous solutions Give OH- ions in aqueous solutions
2. On the basis of origin, acids are classified as:
a. Organic acids: Acids derived from living organisms like plants and animals are called organic acids. They are weak acids and are not harmful for living organisms. For example: citric acid is present in fruits, acetic acid present in vinegar, oxalic acid present in tomato, tartaric acid present in tamarind, lactic acid present in sour milk and curd.
b. Mineral acids: They are also called inorganic acids. They are dangerous and corrosive. Special precautions have to be taken while handling them. For example: sulphuric acid (H2SO4), hydrochloric acid (HCl) etc.
3. On the basis of their strength, acids are classified as:
a. Strong acids: Strong acids are those acids which completely dissociate into its ions in aqueous solutions. Example: nitric acid (HNO3) , sulphuric acid(H2SO4), hydrochloric acid(HCl)
b. Weak acids: Weak acids are those acids which do not completely dissociate into its ions in aqueous solutions. For example: carbonic acid (H2CO3), acetic acid (CH3COOH)
4. On the basis of their concentration, acids are classified as: a. Dilute acids: Have a low concentration of acids in aqueous
solutions.
b. Concentrated acids: Have a high concentration of acids in aqueous solutions.
5. Alkalies: Water soluble bases are called alkalies. For example: Sodium hydroxide (NaOH), potassium hydroxide(KOH)
6. On the basis of their strength, bases are classified as:
a. Strong bases: Strong bases are those bases which completely dissociate into its ions in aqueous solutions. Example: sodium hydroxide (NaOH), potassium hydroxide (KOH)
b. Weak bases: Weak bases are those bases which do not completely dissociate into its ions in aqueous solutions. For example: ammonium hydroxide (NH4OH)
7. On the basis of their concentration, bases are classified as: a. Dilute bases: Have a low concentration of alkali in aqueous
solutions.
b. Concentrated bases: Have a high concentration of alkali in aqueous solutions.
8. Acids and bases conduct electricity because they produce ions in water. There is a flow of electric current through the solution by ions. 9. Indicators are those chemical substances which behave differently in
acidic and basic medium and help in determining the chemical nature of the substance. Acid base indicators indicate the presence of an acid or a base by a change in their colour or smell.
10.Indicators can be natural or synthetic.
11.Olfactory indicators: These are those indicators whose odour changes in acidic or basic medium. Example: onion
12.Onion: Smell of onion diminishes in a base and remains as it is in an acid.
13.Vanilla essence: The odour of vanilla essence disappears when it is added to a base. The odour of vanilla essence persists when it is added to an acid.
14.Turmeric: In acids, yellow colour of turmeric remains yellow. In bases, yellow colour of turmeric turns red.
15.Litmus: Litmus is a natural indicator. Litmus solution is a purple dye which is extracted from lichen. Acids turn blue litmus red. Bases turn red litmus blue. Water is essential for acids and bases to change the colour of litmus paper. Remember that litmus paper will act as an indicator only if either the litmus paper is moist or the acid or base is
in the form of aqueous solution. This is because acids and bases release H+ and OH- ions respectively in aqueous solutions.
16.Phenolphthalein: Phenolphthalein remains colourless in acids but turn pink in bases.
17.Methyl orange: Methyl orange turns pink in acids and becomes yellow in bases.
18.Reaction of acids and bases with water:
Acids Bases
Release H+ or H3O+ ions in water Release OH- ions in water
HCl + H2O → H3O+ + Cl- NaOH(s)H O2 →Na (aq) OH (aq)+ + −
19.Reaction of acids and bases with metals:
Metals displace hydrogen from the acids and form salt and hydrogen gas. This is a displacement reaction. So, acids react with only those metals which are placed above hydrogen in the reactivity series so that metals can displace hydrogen from acids.
Zn + H2SO4 → ZnSO4 + H2
Metal Acid Salt Hydrogen gas
Bases react with some metals to form salt and hydrogen gas. Zn + 2 NaOH → Na2ZnO2 + H2
Metal Base Sodium Hydrogen gas zincate
(salt)
Bases do not react with all the metals to form salt and water. 20.Reaction of acids and bases with metal carbonates:
Acids react with metal carbonate to form salt, water and release carbon dioxide.
2 3 2 2
Na CO +2HCl→2 NaCl CO+ +H O
21.Reaction of acids and bases with metal bicarbonates:
Acids react with metal bicarbonate to form salt, water and release carbon dioxide.
3 2 2
NaHCO +HCl→NaCl CO+ +H O
Bases do not react with metal bicarbonates.
22. Reaction of acids with bases: Neutralisation reaction: Acids react with bases to form salt and water.
HCl + NaOH → NaCl + H2O or
H+ +OH- → H2O
23.Reaction of acids with metallic oxides:
Metallic oxides are basic. Therefore, acids react with metallic oxides to form salt and water.
HCl + CuO → CuCl2 + H2O
24.Reaction of bases with non-metallic oxides: Non – metallic oxides are acidic in nature. Bases react with non- metallic oxides to form salt and water. Example: CO2
Ca(OH)2 + CO2 → CaCO3 + H2O
25.Amphoteric oxides: Oxides which show acidic as well as basic properties. For example: ZnO, Al2O3
HCl + ZnO → ZnCl2 + H2O Zn + 2 NaOH → Na2ZnO2 + H2O
26.Neutral oxides: Oxides which are neither acidic nor basic are called neutral oxides. Example: CO
27.pH: It is used to find out the strength of acids and bases i.e., how strong or weak the acid or a base is. p in pH stands for ‘potenz’ in German. The strength of acids and bases depends on the number of H+ ions and OH- ions produced respectively.
28.pH scale: A scale for measuring hydrogen ion concentration in a solution is called pH scale.
29.On pH scale, we measure pH from 0 to 14. pH value:
pH Type of solution
Less than 7 Acidic
Equal to 7 Neutral
30.More the hydrogen ion (or hydronium ion) concentration, lower is the pH value.
31.More the hydroxyl ion concentration, higher is the pH value. 32.Variation in pH:
33. Acids which produce more hydrogen ions are said to be strong acids and acids which produce less hydrogen ions are said to be weak acids. In other words, strong acids have a lower pH value than weak acids. 34. Bases which produce more hydroxyl ions are said to be strong bases
and bases which produce less hydroxyl ions are said to be weak bases. In other words, strong bases have a higher pH value than weak bases. 35. Living organisms are pH sensitive. Human body works within a pH
range of 7.0 to 7.8.
36. Rain water with a pH less than 5.6 is called acid rain. This acid rain if it flows into river water makes the survival of aquatic life difficult.
37. Plants also require a specific pH range of soil for their healthy growth. 38. pH of our digestive system: Our stomach produces hydrochloric acid
for digestion of food. But during indigestion, excess of acid is produced in the stomach and therefore, the pH decreases. This causes pain and irritation. So, to neutralise this excess acid, a mild base is used. This mild base works as an antacid. An antacid is any substance, generally a base or basic salt, which counteracts stomach acidity.
39.Tooth decay: Tooth decay starts when the pH of the mouth is lower than 5.5. Tooth enamel is made up of calcium phosphate which is the hardest substance in the body. It does not dissolve in water, but is corroded when the pH in the mouth is below 5.5. If food particles remain in the mouth after eating, bacteria present in our mouth
produce acid by degradation of sugar. This decreases the pH of mouth and hence tooth decay occurs. The best way to prevent this is to clean the mouth after eating food. Using toothpastes, which are generally basic, for cleaning the teeth can neutralise the excess acid and prevent tooth decay.
40. pH is also significant as it is used in self defence by animals and plants. Bees use acids in their sting. To neutralise the effect a mild base like baking soda can be used.
41. Sodium hydroxide (NaOH) Preparation:
Chlor Alkali process:
In this process, electricity is passed through an aqueous solution of Sodium chloride (called brine). Sodium chloride decomposes to form sodium hydroxide.Chlorine gas is formed at the anode, and hydrogen gas at the cathode. Sodium hydroxide solution is formed near the cathode.
2NaCl(aq) + 2 H2O (l) → 2NaOH(aq) + Cl2(g) + H2(g)
42.Bleaching powder: Bleaching powder is represented as CaOCl2, though the actual composition is quite complex.
Preparation: Bleaching powder is produced by the action of chlorine on dry slaked lime.
Ca(OH)2 + Cl2 → CaOCl2+ H2O
43.Baking soda: Sodium hydrogen carbonate (NaHCO3) Preparation:
NaCl + H2O + CO2+ NH3 → NH4Cl + NaHCO3 44.Washing soda: Sodium carbonate Na2CO3 .10H2O
Preparation:
In the first step, sodium carbonate is obtained by heating baking soda.
2 NaHCO3
→
HeatNa2CO3 + H2O + CO2
Then washing soda is produced by recrystallisation of sodium carbonate.
Na2CO3 +10H2O → Na2CO3 .10H2O
45.Plaster of Paris: Calcium sulphate hemihydrate CaSO4. ½ H2O
Preparation: Plaster of Paris is prepared by heating Gypsum at 373K. CaSO4. 2H2O
Heat at 373K
→
CaSO4. ½ H2O + 1½ H2O46.Water of crystallisation: It is the fixed number of water molecules present in one formula unit of a salt.
Chapter: Metals and Non – metals
Top concepts:
1. Definition of Metals & Non metals:
Metals Non - metals
These are the substances which are electropositive in nature i.e., they have a tendency to lose electrons
These are the substances which are electronegative in nature, i.e. they have a tendency to gain electrons. They generally have 1, 2, or 3
electrons in their outermost shell.
They generally have 4 to 8 electrons in their outermost shell.
2. Physical properties of Metals and non- metals:
Physical Property Metals Non - metals
Physical state They are generally solids.
Exception: Mercury is a liquid
They are either solids or gases Exception:
Bromine is a liquid
Lustre They have a shiny
lustre which is called metallic lustre
They do not have a shiny lustre
Exception – graphite, iodine
Sonorous They generally produce a sound on striking a hard surface
They are non - sonorous
Malleability Some metals can be beaten into thin sheets. Most malleable gold and silver
Non – metals are not malleable
Ductility The ability of metals to be drawn into thin wires is called ductility Gold is the most ductile metal
Non – metals are not ductile
Electrical conductivity
They are good conductors of electricity
Best conductors: Silver and copper.
Non- metals are generally poor
conductors of electricity Exception: Graphite
Thermal conductivity
They are good conductors of heat Best conductors: Silver and
copper.
Poor conductors : Lead and mercury
They are poor conductors of heat
Hardness They are generally hard
Exception – alkali metals like sodium, potassium
They are generally soft Exception : Diamond is the hardest substance known
Melting point They generally have high melting points Exception – gallium , alkali metals like sodium, potassium Gallium and caesium will melt if you keep them on your palm
They generally have low melting points
Densities They generally have low densities
They generally have high densities
3. The elements which have intermediate properties between those of metals and non-metals are called metalloids.
4. Allotropes are two or more different forms of the same element. 5. Reaction of metals with oxygen: Almost all metals combine with
oxygen to form metal oxides. But all metals do not react with oxygen at the same rate. Different metals show different reactivities towards oxygen.
Metal oxides are basic in nature. But some metal oxides are amphoteric oxides.
6. Most metal oxides are insoluble in water but some of these dissolve in water to form alkalies. Example:
7. Amphoteric oxides: Metal oxides which show both acidic as well as basic behaviour are known as amphoteric oxides. Such metal oxides which react with both acids as well as bases to produce salts and
water. For example: aluminium oxide, zinc oxide, etc. Al2O3 + 6 HCl → 2 AlCl3 + 3 H2O
Al2O3 + 2 NaOH → 2 NaAlO2 + H2O
8. Reaction of metals with water:
Metal Reacts with Products
Potassium Violently with cold water KOH, H2 Sodium Violently with cold water NaOH, H2 Calcium Less violently with cold
water
Ca(OH)2, H2
Magnesium Hot water Mg(OH)2, H2
Aluminium Steam Al2O3, H2
Iron Steam Fe3O4, H2
Zinc Steam ZnO, H2
Lead No reaction at all Silver No reaction at all Gold No reaction at all Copper No reaction at all 9. Reaction of metals with acids:
Metal + Dilute acid → Salt + Hydrogen 10. Reaction of metals with nitric acid:
Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because HNO3 is a strong oxidising agent. It oxidises the H2 produced to water and itself gets reduced to any of the nitrogen oxides (N2O, NO, NO2). But magnesium (Mg) and manganese (Mn) react with very dilute HNO3 to evolve H2 gas.
11. Aqua regia: Aqua regia is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1.
12. Anodising: It is a process of forming a thick oxide layer of aluminium. During anodising, a clean aluminium article is made the anode and is electrolysed with dilute sulphuric acid. The oxygen gas evolved at the anode reacts with aluminium to make a thicker protective oxide layer. This aluminium oxide coat makes it resistant to further corrosion.
13. Reaction of metals with solution of other metal salts:
Metal A + Salt solution of B → Salt solution of A + Metal B (Metal A is more reactive than metal B)
14. Reactivity series: The reactivity series is a list of metals arranged in the order of their decreasing activities.
15. Reaction of metals with non – metals: When a metal and a non- metal react with each other, transfer of electrons take place from metal to non-metal..
16. Ionic compounds: The compounds thus formed by complete transference of electrons from a metal to non- metal are known as ionic compounds. Ionic compounds have strong electrostatic force of attraction between the positive and negative ions.
17. Properties of ionic compounds:
a. Physical nature: Ionic compounds are solids and are somewhat hard.
b. Melting and Boiling points: Ionic compounds have high melting and boiling points
c. Solubility: Electrovalent compounds are generally soluble in water and insoluble in solvents such as kerosene, petrol, etc.
d. Conduction of Electricity: Ionic compounds do not conduct electricity in the solid state but conduct electricity in the molten state or when dissolved in water.
18. Corrosion: The process of slowly eating away of the metal due to attack of air, water, etc., on the surface of the metal is called corrosion.
19. The rusting of iron can be prevented by painting, oiling, greasing, galvanising, chrome plating, anodising or making alloys.
20. Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc. The galvanised article is protected against rusting even if the zinc coating is broken.
21. Alloys: An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal.
22. Alloys and their constituents:
Alloy Constituents
Brass Copper, zinc
Bronze Copper, tin
Steel Iron, carbon
Stainless steel Iron, nickel, chromium
Solder Lead, tin
23. Mineral: The elements or compounds, which occur naturally in the earth’s crust, are known as minerals.
24. Ore: The minerals contain a very high percentage of a particular metal and from which the metal can be profitably extracted is called ore.
25. Gangue: The unwanted materials or impurities present in the ores is called gangue.
26. Enrichment of ore: Ores mined from the earth are usually contaminated with gangue. The removal of gangue from the ore is called enrichment of ore. The process used for enrichment of ores is based on the differences between the physical or chemical properties of the gangue and the ore.
27. Steps involved in the extraction of metals from ores:
28. Metals low in the activity series: Metals low in the activity series are very unreactive. The oxides of these metals can be reduced to metals by heating alone.
29. Metals in the middle of the activity series: The metals in the middle of the activity series are moderately reactive. These are usually present as sulphides or carbonates in nature. They are first converted to metal oxides and then in the next step the metal oxides are reduced to metal.
31. Conversion of ore into oxide form: It can be done in two ways:
Roasting Calcination
The process of heating the sulphide ore in the presence of sufficient supply of air to convert it into oxide is called roasting.
The process of heating the carbonate ore in the presence of limited supply of air to convert it into oxide is called calcination. This process is used for sulphide
ores.
This process is used for carbonate ores.
Example:
2 ZnS (s) + 3O2 (g) Heat → 2ZnO (s)
+2SO2 (g)
Example:
ZnCO3 (s) Heat → ZnO (s) +
CO2 (g)
32. Metals towards the top of the reactivity series: These are highly reactive metals. Example: Sodium, calcium, magnesium, aluminium are obtained by electrolysis of molten chlorides. These metals are obtained by electrolytic reduction.
33. Electrolytic reduction of molten sodium chloride: At cathode: Na+ + e– → Na
At anode: 2Cl– → Cl
2 + 2e– 34. Electrolytic refining of metal: At anode: M → Mn+ + n e– (Impure metal) At cathode: Mn+ + n e– → M (Pure metal)
Chapter : Carbon and its compounds
Top concepts:
1. Covalent bond: A covalent bond is a bond formed by sharing of electrons between atoms. In a covalent bond, the shared pair of electrons belongs to the valence shell of both the atoms.
2. Conditions for formation of covalent bond:
a. The combining atoms should have 4 to 7 electrons in their valence shell.
b. The combining atoms should not lose electrons easily. c. The combining atoms should gain electrons readily.
d. The difference in electronegativities of two bonded atoms should be low.
3. Properties of covalent compounds:
a. Physical states: They are generally liquids or gases. Some covalent compounds may exist as solids.
b. Solubility: They are generally insoluble in water and other polar solvents but soluble in organic solvents like benzene, toluene etc.
c. Melting and boiling point: They generally have low melting and boiling points.
d. Electrical conductivity: They do not conduct electrical current. 4. Steps for writing the Lewis dot structures of covalent compounds:
a. Write the electronic configuration of all the atoms present in the molecule.
b. Identify how many electrons are needed by each atom to attain noble gas configuration.
c. Share the electrons between atoms in such a way that all the atoms in a molecule have noble gas configuration.
d. Keep in mind that the shared electrons are counted in the valence shell of both the atoms sharing it.
5. Electronic configuration of some non- metals: Name of element Sy mb ol Ato mic No. Elec tron s Distribution of electrons Valen cy Type of element
Hydrogen H 1 1 1 1 Non – metal
Carbon C 6 6 2, 4 4 Non – metal
Nitrogen N 7 7 2, 5 3 Non – metal
Oxygen O 8 8 2, 6 2 Non – metal
Fluorine K 9 9 2, 7 1 Non – metal
Phosphorus P 15 15 2, 8, 5 3 Non – metal
Sulphur S 16 16 2, 8, 6 2 Non – metal
Chlorine Cl 17 17 2, 8, 7 1 Non – metal
Argon Ar 18 18 2, 8, 8 0 Noble gas
6. Carbon forms covalent bonds.
7. Electronegativity – It is the ability of an atom to attract a shared pair of electrons towards itself.
8. If the atoms forming a covalent bond have different
electronegativities, the atom with higher electronegativity pulls the shared pair of electron towards itself. Thus, the atom with the higher electronegativity develops a partial negative charge and the atom with the lower electronegativity develops a partial positive charge. This covalent bond with some polarity is called polar covalent bond. 9. Carbon forms a large number of compounds because of two unique
properties: a. Tetravalency b. Catenation 10.Tetravalency of carbon: Atomic number = 6 Electronic configuration: 2, 4 Valence electrons = 4 Valency = 4
So, carbon needs four electrons to attain noble gas configuration. Or in other words, carbon has the ability to form four bonds with carbon or atoms of other mono-valent elements.
11.Catenation: Carbon has the unique ability to form bonds with other atoms of carbon, giving rise to large molecules. This property is called catenation.
12.Steps for writing the Lewis dot structures of Hydrocarbons:
a. Write the electronic configuration of all the atoms present in the molecule.
b. Identify how many electrons are needed by each atom to attain noble gas configuration.
c. First complete the noble gas configuration of all the hydrogen atoms by bonding each hydrogen atom with a carbon atom by a single bond.
d. The remaining valency of each carbon is completed by forming carbon – carbon single, double or triple bonds.
e. Keep in mind that the shared electrons are counted in the valence shell of both the atoms sharing it.
13.Classification of hydrocarbons:
a. Aliphatic or open chain hydrocarbons: These are the carbon compounds which have carbon carbon long open chains. They are classified as:
i. Saturated hydrocarbons: These hydrocarbons have all carbon – carbon single bonds.
ii. Unsaturated hydrocarbons: These hydrocarbons have at least one carbon – carbon double or triple bonds.
• Hydrocarbons with at least one carbon-carbon double bond are called alkenes.
General formula = CnH2n wheren = number of carbon atoms
• Hydrocarbons with at least one carbon-carbon triple bond are called alkynes.
General formula = CnH2n-2 wheren = number of carbon atoms
b. Cyclic or closed chain hydrocarbons: These are the hydrocarbons which have carbon carbon closed chain. They are classified as:
i. Alicyclic hydrocarbons: These are the hydrocarbons which do not have benzene ring in their structure.
ii. Aromatic hydrocarbons: These are the hydrocarbons which have benzene ring in their structure. When hydrogen bonded to carbon of benzene is substituted with halogens, radicals or other functional groups, the derivatives are called aromatic compounds.
14.Benzene: It is an aromatic hydrocarbon which has the molecular formula C6H6. It has alternating carbon - carbon single and double bonds.
15.IUPAC name of hydrocarbon consists of two parts:
a. Word root: Number of carbons in the longest carbon chain Number of carbon atoms Word root (Greek name) 1 Meth 2 Eth 3 Prop 4 But 5 Pent 6 Hex 7 Hept 8 Oct 9 Non 10 Dec
b. Suffix: Depends on the type of carbon – carbon bond: for single bond, suffix is –ane ; for double bond, suffix is –ene, and for triple bond suffix is –yne
16.Steps to write the IUPAC nomenclature of hydrocarbons: a. Select the parent carbon chain:
i. Select the longest carbon chain as the parent chain. ii. If a double or a triple bond is present in the carbon chain,
it should be included in the parent chain.
b. Number the parent carbon chain from that carbon end such that the double bond, triple bond or side chain gets the lowest
number.
c. Identify and name the side chain if any: -CH3 is named as
methyl, -C2H5 is named as ethyl etc. Also identify the position of the side chain.
d. Write the name of the hydrocarbon as:
Position number-name of the side chain word root – Position number- suffix
Example: 2-Methyl but-1-ene
e. Remember if the hydrocarbon is an alkane, the position number of suffix is not written.
17.Types of formula for writing hydrocarbons:
a. Molecular formula: The actual number of each type of atom present in the compound.
b. Structural formula: The actual arrangement of atoms is written c. Condensed formula: It is the shortened form of the structural
18.Conditions for Isomerism:
a. Only alkanes with more than three carbon atoms can have isomers.
b. The side chains cannot be present on the terminal carbons. 19. How to write different chain isomers of hydrocarbons:
a. First draw the different carbon chains keeping in mind the conditions for isomerism.
b. Complete the tetravalency of carbon by forming single covalent bonds with hydrogens.
c. In the end, check that the molecular formula of each isomer should be same.
20. How to write different position isomers of unsaturated hydrocarbons: a. First draw the different carbon chains keeping in mind the
conditions for isomerism.
b. If it is an alkene draw the first isomer always by drawing a double bond between C1 and C2 or if it is an alkyne draw the first isomer always by drawing a triple bond between C1 and C2 c. The next isomers will be dawn by drawing the same chain and changing the positions of the double and triple bonds in alkenes and alkynes respectively.
d. Complete the tetravalency of carbon by forming single covalent bonds with hydrogens.
e. In the end, check that the molecular formula of each isomer should be same.
21.Homologous Series: A series of organic compounds in which every succeeding member differs from the previous one by –CH2 or 14 u. The molecular formula of all the members of a homologous series can be derived from a general formula.
22.Properties of a homologous series: As the molecular mass increases in a series, so physical properties of the compounds show a variation, but chemical properties which are determined by a functional group
remain the same within a series.
23.Homologous series of alkanes: General formula: CnH2n+2 wheren = number of carbon atoms
24. Homologous series of alkenes: General formula: CnH2n wheren = number of carbon atoms
25.Homologous series of alkynes: General formula: = CnH2n-2 wheren = number of carbon atoms
26.Functional group: An atom or a group of atoms which when present in a compound gives specific properties to it, regardless of the length and nature of the carbon chain is called functional group.
a. Free valency or valencies of the group are shown by the single line. b. The functional group is attached to the carbon chain through this
valency by replacing one hydrogen atom or atoms.
c. Replacement of hydrogen atom by a functional group is always in such a manner that valency of carbon remains satisfied.
d. The functional group, replacing the hydrogen is also called as hetero atom because it is different from carbon, and can be nitrogen, sulphur, or halogen etc.
27.Some functional groups in carbon compounds:
Heteroatom Functional group Formula of the functional group Suffix Cl/ Br Halo- Chloro Bromo -Cl -Br Named as prefix Chloro – Bromo - Alcohol -OH - ol Aldehyde -al Ketone -one Oxygen
28. Steps to write the IUPAC name of organic compounds: i. Select the parent carbon chain:
1. Select the longest carbon chain as the parent chain.
2. If a double or a triple bond is present in the carbon chain, it should be included in the parent chain. 3. If a functional group is present, the carbon chain
should include the functional group.
ii. Number the parent carbon chain from that carbon end such that the functional group, double bond, triple bond or side chain gets the lowest number.
Remember here that the aldehyde and carboxylic acid functional group are present on the terminal carbon atom. iii. Identify the name and position of the functional group,
double bond, triple bond or side chain.
iv. The name of the functional group is written with either a prefix or a suffix as given in the above table.
v. If the name of the functional group is to be given as a suffix, the name of the carbon chain is modified by
deleting the final ‘e’ and adding the appropriate suffix. For example, a three-carbon chain with a ketone group would
be named in the following manner – Propane – ‘e’ = propan + ‘one’ = propanone.
vi. Remember that in the compounds which have carbon containing functional groups, the name of the word root includes the functional group carbon atom also.
vii. If the carbon chain is unsaturated, then the final ‘ane’ in the name of the carbon chain is substituted by ‘ene’ or ‘yne’ as given in the table above. For example, a three-carbon chain with a double bond would be called propene and if it has a triple bond, it would be called propyne.
29. Difference between chemical properties of saturated and unsaturated hydrocarbons:
Saturated hydrocarbons Unsaturated hydrocarbons Give a clean blue flame on complete
combustion and on incomplete combustion give a yellow sooty flame.
Give a yellow sooty flame on combustion.
Undergo substitution reaction like chlorination
Undergo addition reaction like hydrogenation, addition reaction with bromine in carbon tetrachloride Are fairly unreactive and inert in the
presence of most reagents
Are reactive
30.Catalysts are substances that cause a reaction to occur or proceed at a different rate without the reaction being affected.
31.Oxidizing agents are substances which are capable of providing oxygen to other compounds for their oxygen. Example: Alkaline KMnO4,
acidified K2Cr2O7 etc. 32.Reactions of ethanol: 2 CH3CH2OH + 2 Na → 2 CH3CH2ONa + H2 Hot conc. H SO2 4 → 3 2 2 2 2 2 CH CH OH CH =CH + H O + + →
Alkaline KMnO4 Heat
3 2 Or acidifiedK Cr O2 2 7 Heat 3
2 CH CH OH CH COOH
33.Reactions of ethanoic acid:
CH3COOH + NaOH → CH3COONa + H2O acid → 3 3 2 3 2 3 CH COOH +CH CH OH CH COO CH CH ester + → 3 2 5 3 2 5
CH COO C H NaOH CH COONa+ C H OH
→ +
3 3 2
CH COOH +NaOH CH COONa H O
→ + +
→ + +
3 2 3 3 2 2
3 3 3 2 2
2 CH COOH +Na CO 2 CH COONa H O CO
34. Catalysts are substances that cause a reaction to occur or proceed at a different rate without the reaction being affected.
35.Soaps are sodium or potassium salts of long chain carboxylic acids. 36. Structure of soap molecule: The structure of soap molecule consists of
a long hydrocarbon tail at one end which is hydrophobic in nature. The other end is the ionic part which is hydrophilic in nature.
37.Cleansing action of soap: When soap is at the surface of water, the ionic end of soap orients itself towards water and the hydrocarbon ‘tail’ orients itself aligns itself along the dirt. Thus, clusters of molecules are formed in which the hydrophobic tails are in the interior of the cluster and the ionic ends are on the surface of the cluster. This formation is called a micelle.
Soap in the form of a micelle is able to clean, since the oily dirt will be collected in the centre of the micelle. The micelles stay in solution as a colloid and will not come together to precipitate because of ion-ion repulsion. Now, when water is agitated, the dirt suspended in the micelles is also easily rinsed away.
38.When hard water is treated with soap, scum is formed.This is caused by the reaction of soap with the calcium and magnesium salts, which cause the hardness of water.
39.Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids.
40.Detergents do not form scum with hard water. This is because the charged ends of these compounds do not form insoluble precipitates with the calcium and magnesium ions in hard water. Thus, they remain effective in hard water.
41.
Soaps Detergents
Soaps are sodium or potassium salts of long chain carboxylic acids.
Detergents are generally ammonium or sulphonate salts of long chain
carboxylic acids. Soaps are not effective for cleaning
in hard water.
Detergents are effective for cleaning in hard as well as soft water.
Soaps are biodegradable. Detergents are non - biodegradable.
Chapter: Periodic classification of elements
Top concepts
1. Dobereiner’s triads: Johann Wolfgang Dobereiner, a German chemist, classified the known elements in groups of three elements on the basis of similarities in their properties. These groups were called triads.
• Characteristic of Dobereiner’s Triads:
a. Properties of elements in each triad were similar.
b. Atomic mass of the middle elements was roughly the average of the atomic masses of the other two elements.
• Example of Dobereiner’s Triads :
Element Atomic mass Element Atomic mass Element Atomic mass Lithium (Li) 6.9 Calcium (Ca) 40.1 Chlorine
(Cl) 35.5
Sodium (Na) 23.0 Strontium
(Sr) 87.6
Bromine
(Br) 79.9
Potassium
(K) 39.0 Barium (Ba) 137.3 Iodine (I) 126.9
• Limitations: Dobereiner could identify only three triads. He was not able to prepare triads of all the known elements
2. Newlands’ Law of Octaves: John Newlands, an English scientist,
arranged the known elements in the order of increasing atomic masses and called it the ‘Law of Octaves’. It is known as ‘Newlands’ Law of Octaves’ • Characteristics of Newlands’ Law of Octaves
a. It contained the elements from hydrogen to thorium
b. Properties of every eighth element were similar to that of the first element
• Table showing Newlands’ Octaves: sa (do) re (re) ga (mi) ma (fa) pa (so) da (la) ni (ti) H Li Be B C N O F Na Mg Al Si P S Cl K Ca Cr Ti Mn Fe Co and Ni Cu Zn Y In As Se Br Rb Sr Ce and La Zr - -
• Limitations of Newlands’ law of Octaves:
a. The law was applicable to elements upto calcium (Ca) only
b. It contained only 56 elements. Further it was assumed by Newlands that only 56 elements existed in nature and no more elements would be
discovered in the future.
c. In order to fit elements into the table. Newlands’ adjusted two
elements in the same slot and also put some unlike elements under same note. For example cobalt and nickel are in the same slot and these are placed in the same column as fluorine, chlorine and bromine which have very different properties than these elements. Iron, which resembles cobalt and nickel in properties, has been placed differently away from these
elements
3. Mendeleev’s Periodic Table: Dmitri Ivanovich Mendeleev, a Russian chemist, was the most important contributor to the early development of a periodic table of elements wherein the elements were arranged on the basis of their atomic mass and chemical properties..
• Characteristic of Mendeleev’s Period Table:
a. Mendeleev arranged all the 63 known elements in an increasing order of their atomic masses.
b. The table contained vertical columns called ‘groups’ and horizontal rows called ‘periods’.
c. The elements with similar physical and chemical properties came under same groups.
• Mendeleev’s Periodic Law: The properties of elements are the periodic function of their atomic masses.
• Achievements of Mendeleev’s Periodic Table:
a. Through this table, it was very easy to study the physical and chemical properties of various elements.
b. Mendeleev adjusted few elements with a slightly greater atomic mass before the elements with slightly lower atomic mass, so that elements with similar properties could be grouped together. For example, aluminum appeared before silicon, cobalt appeared before nickel.
c. Mendeleev left some gaps in his periodic table. He predicted the
existence of some elements that had not been discovered at that time. His predictions were quite true as elements like scandium; gallium and
germanium were discovered later
d. The gases like helium, neon and argon, which were discovered later, were placed in a new group without disturbing the existing order
• Limitations of Mendeleev’s Periodic Table :
a. He could not assign a correct position to hydrogen in the periodic table b. Positions of isotopes of all elements was not certain according to
Mendeleev’s periodic table
c. Atomic masses did not increase in a regular manner in going from one element to the next. So it was not possible to predict how many elements could be discovered between two elements
4. Modern Periodic Table: Henry Moseley gave a new property of elements, ‘atomic number’ and this was adopted as the basis of Modern Periodic Table’.
• Modern Periodic Law: Properties of elements are a periodic function of their atomic number
• Position of elements in Modern Periodic Table:
a. The modern periodic table consists of 18 groups and 7 periods b. Elements present in any one group have the same number of valence electrons. Also, the number of shells increases as we go down the group.
c. Elements present in any one period, contain the same number of shells. Also, with increase in atomic number by one unit on moving from left to right, the valence shell electron increases by one unit
• Trends in the Modern Periodic Table:
(i) Valency: Valency of an element is determined by the number of valence electrons present in the outermost shell of its atom
• Valency of elements in a particular group is same
• Valency of elements in a particular period increases by one unit from left to right with the increase in atomic number by one unit
(ii) Atomic Size: Atomic size refers to the radius of an atom. • In a period, atomic size and radii decreases from left to right. This is due to increase in nuclear charge which tends to pull the electrons closer to nucleus and reduces size of atom
• In a group, atomic size and radii increases from top to bottom. This is because on moving down, new shells are added. This increases distance between outermost electrons and nucleus which increases the size of atom (iii) Metallic and Non- metallic Properties:
• The tendency to lose electrons from the outermost shell of an atom, is called metallic character of an element
• Metallic character decreases across a period and increases down the group
• The tendency to gain electron in the outermost shell of an atom, is called non- metallic character of an element
• Non-metallic character increases across a period and decreases down the group
• Elements intermediate between metal and non-metals that show characteristic of both metals and non-metals are called as semi-metals or metalloids
5. Metals have a tendency to loose electrons while forming bond. Hence they are electropositive in nature
6. Non-metals have a tendency to gain electrons while forming bond. Hence they are electronegative in nature
7. Oxides formed by metals are generally basic and oxides formed by non-metals are generally acidic
Ch: Life Processes.
Key learnings:
1) The ability to perform the basic life processes distinguishes a living organism from a non-living one.
2) Life processes are the vital processes carried out by living organisms in order to maintain and sustain life. Molecular movements are essential to carry out the various life processes.
3) Specialised body parts perform the various life processes in multicellular organisms. No such organs are present in unicellular organisms.
4) Energy required to carry out the different life processes, is obtained from carbon-based food sources through nutrition.
5) Depending on the mode of obtaining nutrition, organisms are classified as autotrophs or heterotrophs.
i) Autotrophs can prepare their own food from simple inorganic sources like carbon dioxide and water. (eg- green plants, some bacteria)
ii) Heterotrophs cannot synthesize their own food and is dependent on the autotrophs for obtaining complex organic substances for nutrition. (eg. – animals)
6) Green plants prepare their food by the process of photosynthesis. Here, they utilize CO2, H2O and sunlight, with the help of chlorophyll, giving out O2 as a byproduct.
7) In the light reaction of photosynthesis, light energy is absorbed and converted to chemical energy in the form of ATP. Also water molecules are split into hydrogen and oxygen.
8) Carbon dioxide is reduced to carbohydrates in the dark phase of photosynthesis.
9) Plants carry out gaseous exchange with surrounding through stomata.
10) Heterotrophs may be herbivores, carnivores, parasites or saprophytes.
11) In Amoeba, digestion occurs in the food vacuole, formed by the engulfing of food by its pseudopodia.
12) In humans, digestion of food takes place in the alimentary canal, made up of various organs and glands.
13) In mouth, food is crushed into small particles through chewing and mixed with saliva, which contains amylase for digesting starch.
14) On swallowing, food passes through pharynx and oesophagus to reach stomach. The gastric juice contains pepsin (for digesting proteins), HCl and mucus.
16) Pancreatic juice contains enzymes amylase, trypsin and lipase for digesting starch, proteins and fats respectively.
17) In the small intestine, carbohydrates, proteins and fats are completely digested into glucose, amino acids, and fatty acids and glycerol respectively.
18) The villi of small intestine absorb the digested food and supply it to every cell of the body.
19) The undigested food is egested from the body through anus.
20) During respiration, the digested food materials are broken down to release energy in the form of ATP.
22) Depending on the requirement of oxygen, respiration may be i) Aerobic - occurring in presence of oxygen or
ii) Anaerobic – occurring in absence of oxygen.
23) The end-products are lactic acid or ethanol + CO2, in anaerobic
respiration or CO2 and water in aerobic respiration. Large amount of energy is released in aerobic respiration as compared to anaerobic respiration.
24) Plants release CO2 at night and oxygen during the day.
25) Terrestrial organisms use atmospheric oxygen for respiration whereas aquatic organisms use the dissolved oxygen in water.
26) In humans, air takes the following path on entering the nostrils.
Nostrils Nasal passage Pharynx Larynx Trachea Bronchus Bronchiole Alveolus.
27) The alveoli of lungs are richly supplied with blood and are the sites where exchange of gases (O2 and CO2) occurs between blood and atmosphere.
28) In humans, the respiratory pigment haemoglobin, carry oxygen from lungs to different tissues of the body.
30) In humans, the circulatory system transports various materials
throughout the body and is composed of the heart, blood and blood vessels.
31) Human heart has 4 chambers – 2 atria (right and left) and 2 ventricles (right and left). Right half of the heart receives deoxygenated blood whereas the left half receives oxygenated blood.
32) Ventricular walls are much thicker than atrial walls.
33) Arteries carry blood from heart to different parts of the body whereas veins deliver the blood back to the heart. Arteries are connected to veins by thin capillaries, wherein materials are exchanged between blood and cells.
34) Humans show double circulation and complete separation of oxygenated and deoxygenated blood.
35) Blood platelets are essential for clotting of blood at the place of injury and thus preventing blood loss.
36) Lymphatic system consists of lymph, lymph nodes, lymphatic capillaries and lymph vessels which drain into larger veins. Lymph is also important in the process of transportation.
37) In plants, water is transported through the xylem tissue, from roots to the aerial parts of the plant. Root pressure and transpiration pull are the major forces involved in pulling water up the xylem.
38) Translocation of food is carried out through phloem tissue from leaves and storage organs to other parts of the plant. This process requires energy from ATP.
39) During excretion, the harmful metabolic nitrogenous wastes generated are removed from the body.
40) In humans, a pair of kidneys, a pair of ureters, urinary bladder and urethra constitutes the excretory system.
41) Nephrons are the basic filtration units of kidneys. They carry out filtration, selective reabsorption and tubular secretion to form urine in kidney, which is then passed out through the urethra, via the ureters and urinary bladder.
42) Plants do not have an excretory system and carries out excretion in various ways like transpiration, releasing wastes into surrounding soil, losing the leaves and storing in cell vacuoles and in old xylem.
Top definitions
1) Life processes - The vital processes carried out by living organisms in order to maintain and sustain life.
2) Nutrition - The process of obtaining and utilizing the nutrients necessary to sustain life.
3) Autotrophic nutrition - Nutrition characterized by the ability to use simple inorganic substances for the synthesis of more complex organic compounds, as in green plants and some bacteria
4) Autotroph - An organism capable of synthesizing its own food from simple inorganic substances, using light or chemical energy.
5) Heterotrophic nutrition – A type of nutrition in which energy is derived from the intake and digestion of organic substances, normally plant or animal tissues
6) Heterotrophs – An organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition
7) Photosynthesis – The process by which plants and other organisms generate carbohydrates and oxygen from carbon dioxide and water using light energy, with the help of chlorophyll.
8) Stomata – The minute pores present in the epidermis of a leaf or stem through which gaseous exchange and transpiration occur.
9) Alimentary canal – A long tube extending from the mouth to the anus that has regions specialized for ingestion, digestion,
absorption, and egestion.
10) Enzymes – The biological catalysts which speed up the rate of biochemical reactions in the body.
11) Peristalsis – The process of wave-like contractions and relaxations of the alimentary tract that propels the food forward through the tract.
12) Gastric glands – The glands present in the wall of the stomach that release HCl, pepsin and mucus.
13) Pepsin – A digestive enzyme found in gastric juice that catalyzes the breakdown of proteins to peptides.
14) Emulsification of fat – A process in which bile salts emulsifies fat globules, i.e. increases the surface area of the oil–water interface, which promotes the breakdown of fats by pancreatic lipase.
15) Bile – A digestive juice secreted by the liver, stored in the gallbladder and aids in the digestion of fats.
16) Pancreatic juice - A clear alkaline secretion of the pancreas containing enzymes that aid in the digestion of proteins, carbohydrates, and fats.
17) Trypsin – A pancreatic enzyme that catalyzes the breakdown of proteins into smaller units.
18) Lipase – An enzyme that catalyze the breakdown of fats into fatty acids and glycerol.
19) Intestinal juice – The digestive fluid secreted by the glands lining the walls of the small intestine.
20) Villi – The numerous projections arising from the inner lining of the small intestine, which increase the surface area for absorption.
21) Egestion – The elimination of the waste and undigested matter from the digestive tract through the anus.
22) Respiration – The process by which food is burned by living cells to release energy in the form of ATP, for various body purposes.
23) Aerobic respiration – The metabolic process that uses oxygen to break down food and produce carbon dioxide and water, along with the release of energy.
24) Anaerobic respiration – The metabolic process by which nutrients are broken down in the absence of oxygen to release energy.
25) Alveoli – The tiny air sacs of the lungs where gas exchange occurs with the circulatory system.
26) Trachea – A thin walled tube of the respiratory system with cartilaginous rings that conveys inhaled air from the larynx to the bronchi.
27) Bronchus – Either of the two main branches of the trachea, which delivers air to the lungs from trachea.
28) Haemoglobin – The respiratory pigment present in the red blood cells of vertebrates, which transports oxygen from lungs to the tissues.
29) Blood plasma – The fluid portion of the blood in which the blood cells are normally suspended.
30) Atria – The two upper chambers in the heart, which receive blood from the veins and push it into the ventricles.
31) Ventricles – The two lower chambers of the heart, which receive blood from the atria and pump it into the arteries.
32) Double circulation – A type of circulation in which the blood flows through the heart twice, during each cycle of passage through the body.
33) Arteries – The blood vessels which carry blood away from the heart to various organs of the body.
34) Veins – The blood vessels which collect blood from different organs of the body and bring it back to the heart.
35) Blood clotting – The process by which the blood coagulates to form solid masses, or clots so as to prevent blood loss during injury.
36) Blood clot - A semisolid gelatinous mass of coagulated blood that consists of red blood cells, white blood cells, and platelets
entrapped in a fibrin network.
37) Root pressure – Pressure exerted in the roots of plants as the result of osmosis that causes sap to rise through a plant stem to the leaves.
38) Transpiration – The loss of water vapour from the aerial parts of the plant.
39) Translocation – The transport of soluble products of
photosynthesis from leaves or storage organs to other parts of the plant through phloem.
40) Excretion – The biological process by which the harmful metabolic wastes are removed from the body.
41) Kidney – Either of the two bean-shaped excretory organs that filter wastes (especially urea) from the blood and excrete them and water in urine
.
42) Nephron – The basic filtration unit in the kidneys, which removes waste products from the blood and forms urine
.
Top Reactions
1) 2 2 ChlorophyllSunlight 6 12 6 2 Glu cos e
6CO
+
6H O
→
C H O
+
6O
Top diagrams 1.
3.
5.
Chapter : Control and coordination. Key Learnings
1) A system of control and coordination is essential in living organisms so that the different body parts can function as a single unit to maintain homeostasis as well as respond to various stimuli.
2) In animals, the nervous system and hormonal system are responsible for control and coordination.
3) Neurons are specialized cells of the nervous system. They use electrical and chemical signals for transferring information.
4) Receptors are specialized tips of the nerve fibres that collect the information to be conducted by the nerves.
5) Nerve impulses travel in the following manner from one neuron to the next : Dendrites Cell body Axon Nerve endings at the
tip of axon Synapse Dendrite of next neuron.
6) Chemicals released from axon tip of one neuron, cross the synapse or neuromuscular junction to reach the next cell (neuron or muscle fibre).
7) Nerve impulses from many neurons interact to carry out the complex process of thinking.
8) Central nervous system and peripheral nervous system are parts of our nervous system.
9) Central nervous system is made up of the brain and spinal cord. 10) Spinal cord controls the reflex actions and conducts messages
between different parts of the body and brain.
11) Reflex action is an automatic, rapid and immediate reaction to a stimulus and is below the level of consciousness. No thinking is
involved in reflex action.
12) Reflex arc is the neural pathway that mediates a reflex action. Pathway of reflex arc : Receptor Sensory neuron Relay neuron Motor neuron Effector
13) The sensory neurons of reflex arcs synapse in the spinal cord which then activates the spinal motor neurons without delay to execute a quick action, especially in case of emergencies. The brain also receives the information while the reflex action occurs.
14) The 3 main parts of the brain are forebrain, midbrain and hindbrain.
15) The largest part of the brain, the forebrain, is the main thinking region. It is made up of cerebrum, hypothalamus and thalamus. Cerebellum, pons and medulla constitute the hindbrain.
16) Cerebrum is the largest part of the brain whereas the cerebellum is the second largest part.
17)
Part of brain Function
Cerebrum Governs intelligence, thinking,
memory and other mental abilities, voluntary actions, sensations, emotions and speech
Hypothalamus Coordinates messages from the
autonomous nervous system,
controls certain involuntary actions, as well as the sexual and emotional behaviour and forms an axis with the pituitary
Thalamus Functions as major coordinating
center for sensory and motor signaling.
Midbrain Acts as the coordinating centre
between forebrain and hindbrain; also controls certain involuntary movements
Cerebellum Responsible for precision and fine
control of voluntary movements as well as maintaining posture and equilibrium of the body
Pons Relays impulses between the lower
cerebellum and spinal cord, and higher parts of the brain like the cerebrum and mid brain; also regulates respiration
Medulla Contains vital centres for controlling
blood pressure, respiration, swallowing, salivation, vomiting, sneezing and coughing.
18) Brain is protected by a bony box called cranium, within which are present 3 layers of fluid-filled membranes for absorbing shock. 19) Peripheral nervous system consists of cranial nerves and spinal
nerves and assists in transmitting information between central nervous system and rest of the body.
20) Reflex actions, voluntary actions and involuntary actions are the various types of responses shown by the nervous system.
21) The sense organs detect changes in surroundings and pass this information to the central nervous system, which after processing the information, acts through the muscles.
22) `The movements of muscle tissues are brought about by the contraction and relaxation of the contractile proteins in response to nerve impulses.
23) Plants lack nervous and muscular system.
24) Plants respond to stimuli by showing 2 types of movements – growth independent and growth dependent.
25) Growth independent movements are usually quicker than
growth dependent ones, and involve the use of electrochemical signals by the plant. To achieve this movement, the plant cells change shape by altering their water content.
26) Growth dependent movements or tropic movements are slow, occurring either towards or away from the stimulus.
27) Tropic movements are shown in response to environmental factors such as light, gravity, water and chemicals.
28) Plant roots are positively geotropic and negatively phototropic whereas plant shoots are usually negatively geotropic and positively phototropic.
29) Pollen tubes show chemotropism by growing towards the ovules.
30) In addition to electrochemical signals, plants and animals use hormones for control and coordination.
31) Important plant hormones are auxin, gibberellin, cytokinin, abscisic acid and ethylene.
Plant hormone Function
Auxin Cell elongation Cytokinin Cell division Gibberellin Growth of stem Abscisic acid Inhibits growth Ethylene Ripening of fruits
32) Auxin causes the bending of plant stem towards light as well as the curling of plant tendrils around a support.
33) Animal hormones do not bring about directional growth
depending on environmental cues, but promote controlled growth in various areas to maintain the body design.
34) The various endocrine glands in humans are hypothalamus, pineal gland, pituitary gland, thyroid gland, parathyroid glands, thymus, pancreas, adrenal glands, ovary (in female) and testis (in males).
35) Some important hormones and their functions in human body:
Hormone Endocrine gland
Function
Growth hormone
Pituitary Regulates growth and development of body
Thyroxin Thyroid gland
Controls carbohydrate, protein and fat metabolism
Adrenaline Adrenal gland
Prepares the body to deal with emergency situations
Insulin Pancreas Regulates blood sugar levels
Testosterone Testis Causes development of sexual organs and secondary sexual characteristics in males Oestrogen Ovary Causes development of sexual organs and
secondary sexual characteristics in females
35) In case of flight or fight reaction to an emergency situation, Adrenal glands release adrenaline into blood which acts on
heart and other tissues causes faster heart beat more oxygen to muscles reduced blood supply to digestive system and skin diversion of blood to skeletal muscles increase in breathing rate.
36) Deficiency of iodine causes goiter whereas deficiency of growth hormone and insulin causes dwarfism and diabetes respectively.
