Matter & Materials
What is matter?
Anything that has mass
and occupies space
The History of Matter
• 5TH CENTURY BC Greek philosophers argued about the
nature of matter, some proposed that all matter consisted of four elements: fire, water, air and earth. Other
suggested that it was made up of small indivisible
particles.
• These small particles were called “atomus” meaning small indivisible particles.
• What do we believe today?
• Are atoms indivisible?
• No they can be divided into sub-particles
• Are there only 4 elements?
TODAY’S ATOMIC MODEL:
Solid nucleus containing
positively charged PROTONS and neutral NEUTRONS.
The negatively charged ELECTRONS occupy a 3-dimensional space around the nucleus.
The energy of the electrons is QUANTISED
(the kinetic energy of
the electrons is limited to
CLASSIFICATION OF MATTER
MIXTURES
Consist of two or more
substances of variable
MIXTURES
•
Variable composition.
•
Can be separated by physical means (sorting,
filtration, magnetism etc).
•
The constituents of a mixture are not
chemically bonded together.
•
A mixture is therefore a physical blend of
HOMOGENEOUS MIXTURES
HOMOGENEOUS MIXTURES
•
O
2and
N
2in air.
•
Vinegar in water.
•
Alcohol in water
HETEROGENEOUS MIXTURES
MISCIBLE OR IMMISCIBLE?
•
Substance that mix are called MISCIBLE
•
Substance that don’t mix are called
PURE SUBSTANCES
A substance consisting of one type of
particle
E.g. A single substance in the form a
single
ELEMENT
or a
single
COMPOUND
(two or more
ELEMENT
The simplest form of pure substance
which cannot be broken down into
any simpler types of substances by
ELEMENTS
About 90 naturally occurring elements.
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
PERIODIC TABLE
•
Based on the work of
:
PERIODIC LAW
The periodic law states that the
elements arranged in their increasing
atomic numbers show periodic change
in their properties.
GROUPS
•
There are 8 main groups of elements.
•
I, II, III IV, V, VI, VII & VIII.
•
The elements are grouped according to
CHEMICAL SYMBOLS
C
hemical symbols are used to
represent the names of the
elements. The first letter is
always a capital letter the next
YOU ARE REQUIRED TO KNOW
…..
The first 20 ELEMENTS of the
periodic table and elements of
FIRST 20 ELEMENTS
1. Hydrogen H2. Helium He
3. Lithium Li
4. Beryllium Be
5. Boron B
6. Carbon C
7. Nitrogen N
8. Oxygen O
9. Fluorine F
10. Neon Ne
11. Sodium Na
12. Magnesium Mg
13. Aluminium Al
14. Silicon Si
15. Phosphorus P
16. Sulphur S
17. Chlorine Cl
18. Argon Ar
19. Potassium K
ELEMENTS OF ECONOMIC IMPORTANCE
Metals:
22 Titanium Ti
26 Iron Fe
29 Copper Cu
30 Zinc Zn
47 Silver Ag
50 TinSn
74 Tungsten W
78 Platinum Pt
79 Gold Au
80 Mercury Hg
Halogens:
9 Fluorine F
17 Chlorine Cl
35 Bromine Br
Elements Quiz
•
Give symbols for the
following:
•
Neon (Ne)
•
Silicon (Si)
•
Potassium (K)
•
Silver (Ag)
•
Tin (Sn)
•
Give names for the
following:
•
Al (Aluminium)
•
S (Sulfur / Sulphur)
•
Li (Lithium)
•
Au (Gold)
2.
15.
PHOSPHORUS
THE ELEMENTS ARE DIVIDED INTO
THREE MAIN GROUPS:
1. METALS
METALS
• Have metallic shine (LUSTRE).• Good conductors of heat & electricity.
• Can be pounded into shape (MALLEABLE).
• Can be drawn out into long threads (DUCTILE). • Usually SOLIDS at room temperature (except
mercury).
• High melting and boiling points.
• Reactive metals (excluding copper, gold, silver and
platinum) react with acids to give a salt and hydrogen gas (explodes with a squeaky pop).
NON-METALS
NON-METALS
•
Break easily (
BRITTLE
)
•
Insulators
•
Low melting and boiling points (many are
gases and liquids)
•
Do not react with acids
SEMI-METALS
•
Have properties of both metals and
non-metals.
•
Solids at room temp but
neither
malleable or
ductile.
•
Offer greater resistance than metals, but do
conduct electricity.
•
When they react with metals they behave like
non-metals
•
When they react with non-metals they behave
COMPOUNDS
A pure substance made up of two or
more elements
bonded
together by
means of a
chemical reaction
in a
constant ratio
.
Sodium chloride
Distilled water H
2
O
The formation of water
http://www.biojobblog.com/uploads/image/H2_O2(1).gif
Hydrogen + Oxygen
Water
iron + sulphur = iron sulphide
PHYSICAL AND
PHYSICAL CHANGES
•
Physical changes affect the physical properties
of matter.
•
But no new substances are formed
•
Physical properties include
:
•
Colour, size, shape, mass
•
Density
•
Electrical conductivity
•
Change of state:
e.g. water, ice and steam all
CHEMICAL CHANGES
• New substances are formed during chemical changes. • Chemical bonds form due to electrostatic attraction.
• During chemical reactions energy is required to
break bonds and energy is released when new bonds form.
• Mass is conserved when chemical reactions take
The formation of water
http://www.biojobblog.com/uploads/image/H2_O2(1).gif
Hydrogen + Oxygen
Water
CHEMICAL OR PHYSICAL CHANGE?
IRON POT
CHEMICAL OR PHYSICAL CHANGE?
RAW CHICKEN
=
CHEMICAL
OR
HEATING OF BREAD
BREAD + HEAT =
CHEMICAL CHANGE
MAGNESIUM
MAGNESIUM + OXYGEN + HEAT
STEEL BAR +
HEAT =
IRON + HEAT = HOT IRON
PHYSICAL CHANGE
IODINE CRYSTALS
SUBLIMATION OF
IODINE
IODINE + HEAT = IODINE FUMES
CHANGE OF STATE = PHYSICAL CHANGE
DIRECT CHANGE FROM SOLID TO GAS
HEATING OF
COPPER CARBONATE
COPPER CARBONATE + HEAT
CHEMICAL CHANGE
PHYSICAL VS CHEMICAL CHANGE
PHYSICAL CHANGE
CHEMICAL CHANGE
ENERGY TRANSFERRED ENERGY TRANSFERRED
EASILY REVERSIBLE
NOT REVERSED EASILY
PARTICLES STAY THE
Particles in a solid Particles in a liquid Particles in a gas
Important terms in the particle model of
matter
•
Compress:
make the spaces between particles
smaller so that the substance becomes more
dense.
•
Density:
the ratio of mass to volume in a
substance. I.e. a dense substance has a lot of
mass compressed into a small volume.
SOLIDS
Spaces between particles
•
The spaces between the particles are
small.
•
Solids
cannot be compressed
.
•
Solids are
denser
than liquids and gases
because the particles that have mass occupy
the smallest volume possible.
SOLIDS
Forces between particles:
•
The attractive forces between solid particles
are
strong
because they are close together.
•
Attractive forces hold the particles together in
organised patterns called
crystal lattices
.
SOLIDS
Kinetic energy of particles:
•
The particles have a
low
kinetic energy.
•
They do not move about and can only
vibrate
.
Liquid
Spaces between particles
•
The spaces between the particles are
medium
(larger than in solids and smaller than in
gases.)
•
Liquids are
compressed
with difficulty.
•
I.e. the spaces between the particles can be
made smaller by applying pressure to the
Liquids
Forces between particles:
•
The forces between the particles are
medium,
weaker than those between particles in solids
because they particles are
further apart
, but
the particles still attract each other strongly
enough to stay
together
.
•
We call these forces
cohesive forces
.
•
Liquids will take on the
shape of the container
Liquids
Kinetic energy of particles:
•
The particles have a
medium
kinetic energy.
•
They are constantly moving in
all
directions
and
collide
with each other and the sides of
the container.
•
The particles move
slower
than particles in the
gas phase.
Gases
Spaces between particles
•
The spaces between the particles are
large
,
therefore gases can be
compressed
.
Gases
Forces between particles:
•
The forces between the particles are
weak
because they are so far apart.
•
The particles can only attract or repel each
other when they
collide
with one another.
Gases
Kinetic energy of particles:
•
The particles have a
high
kinetic energy.
•
Particles are
constantly
moving in
all
directions, they
collide
with one
another
and
the side of the
container
they are in.
•
Forces are exerted during the collision
•
Gases will
escape
from containers
that are not closed.
Diffusion
•
Diffusion
is the spontaneous
movement
of
particles from
high
concentration to
low
concentration in the liquid and gas phases.
•
Concentration
: concentration is the
amount of
Heat
•
Heat is energy in transit due to differences in
temperatures.
•
Energy from vibrating molecules is transferred
from one substance to another causing their
molecules to vibrate more and can cause
expansion.
•
The amount of expansion depends on the type
Energy can be transmitted (spread) in 3 ways:
Radiation – energy comes from the sun in about 8 minutes.
Conduction – through solid objects from the hot part to the cooler part. (Most solids are bad conductors).
Convection – the movement of energy from warm gases to cooler parts of the gas. This is an effective way to
spread energy in our atmosphere.
The oil expands when
heated by the hot
water and pushes
up along the
capillary tube.
Heating causes
a change in
Phase Changes: Important Terms
• Freezing: when a substance changes from the liquid
phase to the solid phase.
• Freezing point: the temperature at which a
substance changes from the liquid phase to the solid
phase.
• Melting: when a substance changes from the solid
phase to the liquid phase.
• Melting point: the temperature at which a substance
Phase Changes: Important Terms
• Boiling: when a substance changes from the liquid
phase to the gas phase.
• Boiling point: the temperature at which a substance
changes from the liquid phase to the gas phase.
• Condensation: when a substance changes from the
gas phase to the liquid phase.
• Sublimation: when a substance changes from the
Evaporation
• 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.
boiling gas phase
boiling point 100oC
melting point 0oC
liquid phase
melting
Solid Liquid
Liquid Gas
When solids are heated strongly, they melt at a particular
temperature (called the melting point [M.P.]) & form a liquid at the same temperature.
The same process occurs for liquids at their boiling points
[B.P.] as they change to gases. During a phase change, the temperature stays the same
because the added heat is being used to weaken the forces
SYNTHESIS REACTIONS
•
Reactants combine to form
complex
products.
•
The
products
are as a result of a chemical
reaction (formation of chemical bonds).
•
The products are therefore a
combination
of
the reactants.
•
The product has
new
properties different
EXAMPLES OF SYNTHESIS REACTIONS:
•
PHOTOSYNTHESIS:
Water + Carbon dioxide g Glucose + Oxygen
•
COMBUSTION (reactions with oxygen):
– Carbon + Oxygen g Carbon dioxide
– Sulfur + Oxygen g Sulfur dioxide
– Sodium + Oxygen g Sodium oxide
BURNING
+
=
SULPHUR IRON
CONCLUSIONS
•
During each of the reactions a
new
substance
DECOMPOSITION REACTIONS
•
A Reactant is broken up to form two or more
products
•
The products are as a result of a chemical
reaction (chemical bonds are broken)
•
The products have new properties different
Decomposition of copper carbonate
• Energy to break bonds is supplied by heat
• The copper carbonate is broken down (decomposed)
into two smaller compounds.
• Copper carbonate g copper oxide + carbon dioxide
ELECTROLYSIS OF COPPER CHLORIDE
•
Electrical
energy can be used to bring about a
decomposition reaction instead of heat energy.
•
Such decomposition reactions are called
electrolysis
.
•
The compound copper chloride is broken down
into the elements copper and chlorine.
•
copper chloride
copper
+
chlorine
Electrolysis of water
(http://www.scienceunleashed.ie/graphics.aspx)
EXOTHERMIC REACTIONS
Exothermic reactions are reactions that
release
more energy than they take in.
Thermal and light energy
leaves
the reacting
system and warms up the
surroundings
.
After the initial
activation
energy is supplied,
the reactions are able to continue on their
Examples of exothermic
reactions…
1. Sulphur + oxygen.
2. Sodium + oxygen.
ENDOTHERMIC REACTIONS
Endothermic reactions are reactions which
take
in more energy than they release.
The substance surrounding the reactant (e.g. air
/ container) become
cold
because thermal
energy is drawn out of them.
Examples of endothermic
reactions…
PRACTICAL WORK
Reaction 1:
• Heat copper carbonate in a boiling test-tube until a
colour change is observed.
Reaction 2:
• Add hydrochloric acid to the powder formed in
reaction 1 until a solution forms.
Reaction 3:
• Using carbon electrodes and a battery, put current
Answer the following questions for each
reaction:
1. What do you observe (i.e. See / smell / feel /
hear)
2. Is the reaction a synthesis reaction,
decomposition reaction or something else?
3. Is the reaction endothermic or exothermic?
Reaction 1
1. The blue-green powder breaks down to form a
smaller volume of black powder and gas is released. 2. Decomposition reaction
3. Endothermic (takes in heat) D(heat)
Reaction 2
1. The black powder reacts with the hydrochloric acid to form a blue-green solution. Bubbles form as the acid is added due to heating and the beaker warms up slightly. Pool acid is smelt.
2. Ion exchange reaction (the copper bonds with the chloride and the hydrogen bonds with the oxide) 3. Exothermic (releases heat)
4. copper oxide + hydrogen chloride copper chloride
ELECTROLYSIS OF COPPER CHLORIDE
CuCl
2COPPER FORMING
Reaction 3
1. The salt in the blue-green solution breaks up to form a copper coloured layer on the negative electrode (cathode) and bubbles of gas on the positive
electrode (anode). The bubble have a sharp smell like pool water. The colour of the solution lightens. 2. Decomposition reaction
3. Endothermic (takes in energy)
electricity
Electrolysis of water
Anode
(attracts anions)
Cathode (attracts cations)
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