Matter & Materials
What is matter?
Anything that has ________ and occupies ____________ The History of Matter
• 5TH CENTURY BC Greek philosophers argued about the nature of matter, some proposed that
all matter consisted of four _______________: fire, water, air and earth. Other suggested that it was made up of small indivisible _________________.
• These small particles were called “_____________” meaning small indivisible particles. What do we believe today?
• Are atoms indivisible? _______________________________________________________ • Are there only 4 elements? _____________________________________________________
Today’s atomic model
Solid nucleus containing positively charged ____________ and neutral ________________. The negatively charged _______________ occupy a 3-dimensional space around the nucleus.
The energy of the electrons is __________________
Classification of matter
Mixtures:
______________________________________________________________________________ ______________________________________________________________________________ Mixtures have:
• Variable ___________________.
• Can be separated by _________________ means (sorting, filtration, magnetism etc). • The constituents of a mixture are not chemically bonded together.
• A mixture is therefore a ________________ _______________ blend of substances.
Homogeneous mixtures:_________________________________________________________ ______________________________________________________________________________ e.g.___________________________________________________________________________ Heterogeneous mixtures:_________________________________________________________ ______________________________________________________________________________ e.g.___________________________________________________________________________ MISCIBLE OR IMMISCIBLE?
• Substance that mix are called _______________ • Substance that don’t mix are called ___________
PURE SUBSTANCES
A substance consisting of ______ type of particle e.g. A single substance in the form a single _____________ or a single ________________ (two or more elements chemically bonded together)
ELEMENT:_____________________________________________________________________ ______________________________________________________________________________ _____________________________________________________________________________. • There are about ____ naturally occurring elements that are listed in the periodic table together
with the artificially generated elements.
• An element is defined by the number of protons in its nucleus and this number is called the __________ ____________.
• Periodic law states that the elements arranged in their increasing ____________ show periodic change in their properties. The arrangement includes groups and periods. • There are 8 main groups of elements. I, II, III IV, V, VI, VII.
• The elements are grouped according to similar trends in their chemical and physical properties.
• Chemical Symbols are used to represent the names of the elements. The first letter is always a capital letter the next letter is always a small letter.
• You are required to know the first 20 elements of the periodic table and elements of economic importance (mark these on your periodic table). There will be a quiz on them every-day until you know them.
THE ELEMENTS ARE DIVIDED INTO THREE MAIN GROUPS: METALS
SEMI-METALS (Metalloids) NON-METALS
Metals
• Have metallic shine (____________).
• Good conductors of ________ & ____________________. • Can be pounded into shape (__________________). • Can be drawn out into long threads (______________).
• Reactive metals (excluding copper, gold, silver and platinum) react with ___________ to give a salt and _________________ gas (explodes with a squeaky pop).
Non-metals
• Non-metals have _________________ properties to metals. • Break easily (______________)
• Insulators
• Low melting and boiling points (many are ___________ and liquids) • Do not react with ____________
• __________ (no lustre) Semi-metals
• Have properties of both metals and non-metals.
• ___________ at room temperature but neither __________________ or ______________. • Offer greater resistance than metals, but do conduct ___________________.
• When they react with metals they behave like non-metals • When they react with non-metals they behave like a metal. COMPOUNDS:
______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Bond = ________________________________________________________________________ Examples: (react to form)
Reactants Products
______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Physical & Chemical Change
Physical Changes
• Physical changes affect the physical properties of matter. • But no ______ substances are formed
• Physical properties include :
• Electrical _______________________
• Change of __________: e.g. : water, ice and steam all consist of water molecules.
Chemical Changes
• ______ substances are formed during _________________ changes. • Chemical ___________ form due to electrostatic ____________________.
• During chemical reactions ____________ is required to break bonds and energy is __________________ when new bonds form.
• ________ is conserved when chemical reactions take place because atoms cannot be ______________ or _______________, all the atoms that you started with are still there they are just bonded differently to make new substances.
Physical or Chemical Change?
iron pot rusted iron pot ___________________________________________ raw chicken roasted chicken ___________________________________________
ice water ___________________________________________
bread toast ___________________________________________
magnesium magnesium oxide ___________________________________________ steel red hot steel ___________________________________________ iodine crystals iodine fumes ___________________________________________ copper carbonate copper oxide + carbon dioxide _____________________________________
PHYSICAL CHANGE
CHEMICAL CHANGE
ENERGY TRANSFERRED
ENERGY TRANSFERRED
EASILY REVERSIBLE
NOT REVERSED EASILY
PARTICLES STAY THE
SAME
NEW PARTICLES WITH DIFFERENT PROPERTIES ARE FORMED
Important terms in the particle model of matter
• ________________: the ratio of mass to volume in a substance. I.e. a dense substance has a lot of mass compressed into a small volume.
density= mass volume
• ________________: a push or pull, attraction or repulsion • ________________: force exerted per unit of area
pressure=force area
Illustration : Drawing pin
Look at the shape of a drawing pin
What side do you exert a force with your finger on and why?
Why does the sharp end make a hole in the paper?
(http://www.champaignschools.org/science/images/matter.jpg)
SOLIDS
Spaces between particles
• Solids cannot be ____________________.
• Solids are ____________ than liquids and gases because the particles that have mass occupy the smallest volume possible.
• Therefore, solids are usually ________to the touch.
Forces between particles:
• The attractive forces between solid particles are ___________ because they are __________ together.
• Attractive forces hold the particles together in organised patterns called crystal ____________. • Solids therefore have _______________shapes.
Kinetic energy of particles:
• The particles have a _______ kinetic energy.
• They do not move about and can only ______________. LIQUIDS
Spaces between particles
• The spaces between the particles are _____________ (larger than in solids and smaller than in gases).
• Liquids are ____________________ with difficulty. I.e. the spaces between the particles can be made smaller by applying pressure to the liquids but as the particles get closer together they begin to ___________ each other.
Forces between particles:
• The forces between the particles are _____________, weaker than those between particles in solids because they particles are further apart, but the particles still attract each other strongly enough to stay ________________.
• We call these forces __________________ forces.
• Liquids will take on the ___________ of the container they are poured into. Kinetic energy of particles:
• The particles have a ______________ kinetic energy.
• They are constantly moving in all directions and ______________ with each other and the __________ of the container.
GASES
Spaces between particles
• The spaces between the particles are __________, therefore gases can be _______________. • Compressed gases are ______________.
Forces between particles:
• The forces between the particles are _________ because they are so far apart.
• The particles can only attract or repel each other when they ______________with one another. • The rest of the time they are _________ to move.
Kinetic energy of particles:
• The particles have a _________ kinetic energy.
• Particles are constantly moving in ______ directions, they collide with one another and the side of the container they are in.
• ___________ are exerted during the collisions
• Gases will ____________ from containers that are not closed. DIFFUSION
• ______________________ is the spontaneous movement of particles from high concentration to low concentration in the liquid and gas phases.
• ___________________________ is the amount of particles in a given volume. Demonstration: Gas diffusion tube
The gas diffusion tube illustrates diffusion. For this experiment we put a piece of cotton wool soaked in ammonia on the one side of a glass tube and a piece of cotton wool soaked in hydrochloric acid on the other side of the glass tube.
What do you observe after a while?
Write down a word equation for the reaction that causes this.
Describe the movement of the ammonia molecules
HEAT
• Heat is energy in transit due to differences in ________________________.
• Energy from vibrating molecules is _____________________ from one substance to another causing their molecules to vibrate more and can cause ___________________.
• The amount of expansion depends on the __________ of material.
Demonstration: Kinetic Model
This piece of equipment demonstrates the kinetic model. The ball bearings represent particles in an enclosed space.
Describe the movement of the ball bearings.
What happens to the movement of the ball bearings as they get more energy?
We used electricity to give the ball bearings more energy, how do gas particles get more energy?
What happens to the movement of the ball bearings as we decrease the volume of the container?
Use you observations to write a statement about how you expect particles to move in an enclosed space, depending on how much energy they have and the volume they are forced to occupy.
Energy can be transmitted (spread) in 3 ways:
• ____________________ – energy comes from the sun in about 8 minutes.
• ____________________ – through solid objects from the hot part to the cooler part. (Most solids, excepting metals are bad conductors).
• ____________________ – the movement of energy from warm gases to cooler parts of the gas. This is an effective way to spread energy in our atmosphere.
PHASE CHANGES: IMPORTANT TERMS
• ________________: when a substance changes from the liquid phase to the solid phase. • _______________ ________: the temperature at which a substance changes from the
liquid to the solid phase.
• ______________ _________: the temperature at which a substance changes from the solid phase to the liquid phase.
• ______________: when a substance changes from the liquid phase to the gas phase. • ______________ ________: the temperature at which a substance changes from the
liquid phase to the gas phase.
• ______________________: when a substance changes from the gas phase to the liquid phase.
• ______________________: when a substance changes from the solid phase to the gas phase, without having a liquid phase.
EVAPORATION
• ____________________: when a substance changes from the liquid phase to the gas phase at any temperature.
• Evaporation takes place at all temperatures, but boiling takes place only at the boiling point.
• Evaporation takes place at the surface of the liquid but boiling occurs in all parts of the liquid.
• Evaporation occurs because some particles near the surface of the liquid move quickly enough to break free from the cohesive forces.
• Evaporation causes cooling. Demonstration: Evaporation
This demonstration will illustrate the cooling effect of evaporation. For this experiment we use ether. Ether is called volatile, because it evaporates easily.
Feel the bottom of the glass dish? What do you observe?
Explain in term of phase changes and energy why the dish cools down.
Demonstration: Cooling Curve of Naphthalene
Your teacher will slowly heat a test-tube with some naphthalene (ingredient in moth balls) and a thermometer in it. Note the temperature of the naphthalene every minute. Also note which phases are present by placing a tick in the appropriate block.
When you have gathered your results plot a graph of Temperature vs. time for the experiment. What trends do you see?
Table 1: Change in temperature with time as naphthalene cools
Time (min) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Temperature (°C) Liquid
Solid
What happens to the temperature while the naphthalene is changing phase?
Fig 1: Cooling curve for naphthalene
CHEMICAL REACTIONS
SYNTHESIS REACTIONS
• Reactants combine to form ______________ products.
• The ________________ are as a result of a chemical reaction (formation of chemical bonds). • The products are therefore a ______________________ of the reactants.
• The product has _______ properties different from the reactants. Examples of synthesis reactions:
• Photosynthesis: water + carbon dioxide glucose + oxygen
• Combustion (reactions with oxygen): carbon + oxygen ____________ ____________ sulfur + oxygen ____________ ____________ sodium + oxygen ____________ ___________ potassium + oxygen ____________ ____________ Conclusion: during each of the reactions a _____ more complex substance was formed.
DECOMPOSITION REACTIONS
• A Reactant is ___________ ________ to form two or more products
• The products are as a result of a chemical reaction (chemical bonds are ____________) • Theproducts have new properties different from the reactant.
Decomposition of copper carbonate:
Energy to break bonds is supplied by ______________.
The copper carbonate is ___________ _______ (decomposed) into two smaller compounds. Copper carbonate
____________ __________ + ____________ ______________(blue) (black) (colour-less gas)
• ____________________ energy can be used to bring about a decomposition reaction instead of heat energy.
• Such decomposition reactions are called ______________________.
• The compound copper chloride is broken down into the ______________ copper and chlorine. • copper chloride à ____________ + _______________.
(blue solution) (dark layer on cathode) (bubbles at anode) • Electrolysis can also be used to split water as well.
(http://www.scienceunleashed.ie/graphics.aspx)
EXOTHERMIC REACTIONS
Exothermic reactions are reactions that ______________ more energy than they take in.
Thermal and light energy ____________ the reacting system and warms up the ______________. After the initial ____________________ energy is supplied, the reactions are able to continue on their own.
Examples of exothermic reactions: __________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________
ENDOTHERMIC REACTIONS
The substance surrounding the reactant (e.g. air / container) becomes ________ because thermal energy is drawn out of them. The thermal energy which is taken in, is stored as
________________ __________________ energy.
