State of matter

1. State of matter
Kinetic theory of matter
It states that the particles in solid, liquid and gas are in random motion.
Note: The particles of solids have less energy than liquid or gases.
Ideal gas behaviour
Assumption of the kinetic theory as applied to an ideal gas:
1) The volume of gas particles is negligible compared to the volume of container.
2) There are no intermolecular forces between particles.
3) All collisions are elastic (No loss in K.E).
4) Gas molecules move rapidly and randomly.
5) Distance between particles is large.
A gas that fits this description is called an ideal gas.
Noble gas with small atom (He and Ne) approaches ideal gas behaviour.
Gas that does not fit this behaviour is called a real gas.
General ideal gas equation
pV=nRT or pV=(m/mr)RT
T=Temperature in K
R=8.31 JK-1mol-1
p=Pressure in Pa
V=Volume in m³
Conversion
1) 1 cm3=10-6 m3
2) 1 atm=1.01x105 Pa
3) 1 dm3=10-3 m3

2. Ideal gas behaviour
A gas will approach ideal behaviour under the following condition:
High temperature
At high temperature, the molecules possess large K.E and cannot stick together when they collide. Hence
the bond between the molecules breaks down.
Low pressure
Molecules are far apart with very weak forces of attraction and a volume which is negligible.
Real gases deviate from ideal behaviour under the following condition:
Low temperature
The molecules have less K.E and they tend to stick together. This allows Van der Waal’s forces to operate
between molecules.
High pressure
There is a certain volume when gas molecules are together.
1) Graph of p against V for an ideal gas
2) Graph of p against 1/V for an ideal gas
3) Graph of pV against p for an ideal gas

3. From the graph pV against p, the gas which shows the greatest deviation is Ammonia. This is because the
intermolecular forces of attraction are stronger than the other gases. There are strong H-bonds between
the molecules of Ammonia.
4) Graph of volume against temperature (°C)
5) Graph of volume against temperature (K)
The solid state
Most solids are crystalline. The regular arrangement of ions, molecules or atoms in a crystal is called a
crystal lattice.
1) Ionic lattice
In ionic structure, there are +ve and –ve ions held by strong electrovalent bond. Example: NaCl, MgO

4. Physical properties of ionic compound
1) They have high m.p and b.p as large amount of energy is needed to overcome the strong electrostatic
forces between the ions.
MgO has a higher m.p than NaCl because there is greater electrostatic attraction between the doubly
charged ions in MgO than the singly charged ions in NaCl.
2) They conduct electricity in molten and aqueous state due to mobile ions.
Note: Solid ionic compounds do not conduct electricity since they do not have mobile ions.
3) Many of them are soluble in H2O. The H2O molecules pull the ions off the crystal of the ionic compound.
4) They are brittle. If a stress is applied, the layers of ions may displace slightly. Ions of the same charge are
brought side-by-side and this cause the crystal to split into pieces.
5) They are hard. This is why MgO and Al2O3 are used as refractories.
Refractories are solids used to make crucible, lining of furnaces and incinerators. They can resist high
temperatures without melting or decomposing.

5. 2) Metallic lattice
A metallic lattice consists of +ve metal ions in a sea of delocalised electrons.
Metal bond is strong because of strong electrostatic attraction between the ions and the delocalised
electrons.
Physical properties of metal
1) Most metals have high m.p and b.p as large amount of energy is needed to overcome the strong
electrostatic attraction between the +ve ions and delocalised electrons.
2) They conduct electricity by movement of delocalised electrons.
3) They conduct heat by vibration of metal ions and movement of delocalised electrons.
4) They are malleable and ductile.
The layers can slide over each other without disrupting the metallic bond.
Alloy
An alloy is a mixture of different metals (non metal may also be present).
Structure of Brass

6. Examples of Alloy:
Brass (Copper and Zinc)
Steel (Iron and Copper)
Stainless steel (Fe, Cr, Ni, V, C)
3) Simple molecular lattice
In simple molecular lattice, the particles are held together by weak forces such as:
1) Van der Waal’s
2) Dipole-dipole attraction
3) H-bond
Why ice has a lower density than water?
The H-bond between H2O molecules in ice are positioned tetrahedrally around all oxygen atoms. This
produces empty spaces between H2O molecules. As a result, density of ice is less than that of water. In
liquid H2O, the tetrahedral arrangement is partly broken and molecules are close together, hence having
a high density.
Fullerenes
Fullerenes are allotropes of carbon in the form of hollow spheres or tubes.
Fullerenes have similar structure to graphite that is each carbon atom is bonded to 3 other carbon
atoms.

7. Buckminster
Buckminster contains carbon atoms arrangement in hexagon and pentagon. The C60 has the same
structure of a soccer ball.
Physical properties of Buckminster
1) It has a relatively low sublimation point. It turns directly from solid to vapour state when heated to
about 600 °C. This is because there are weak Van der Waal’s forces between each Buckminster molecule.
2) It is relatively soft because it does not require much energy to overcome the weak intermolecular forces.
3) It is a poor conductor of electricity.
Nanotube
In nanotubes, carbon atoms are arranged hexagonal like in a single layer of graphite.
Physical properties of Nanotube
1) They are good conductor of electricity.
2) They have a very high m.p. This is because there is strong covalent bonding throughout the structure.
3) They have a very high tensile strength.
Uses of Nanotube
1) They are used in tiny electrical circuits as ‘wires’ and as electrodes in paper-thin batteries.
2) They are uses in the treatment of certain types of cancer.

8. Physical properties of compound with simple molecular lattice
1) They have low m.p and b.p.
2) They are non-conductor of electricity.
3) They are usually solid, liquid or gas at rtp.
Allotropes
Allotropes are different crystalline form of the same element.
For example, diamond, graphite and fullerene are allotrope of carbon.
4) Giant molecular structure
They consist of three dimensional network of covalent bond.
They have high m.p and b.p because of large number of strong covalent bonds linking the whole
structure.
Diamond
In diamond, each carbon atom is bonded to 4 other carbon atoms by strong covalent bond.

9. Graphite
In graphite, carbon atoms are arranged in planar layers. Each carbon atom is bonded to 3 other carbon
atoms by strong covalent bond. The delocalised electron is able to move throughout the layers. Hence
graphite conducts electricity.
Why graphite is slippery?
The layers can slide over each other due to presence of weak Van der Waal’s forces.
Silicon (IV) oxide
In SiO2, each silicon atom is bonded to 4 oxygen atoms
.
Graphene
Graphene is a single isolated layer of graphite.
Graphene conducts electricity and heat much better than graphite.

10. Conserving material
Advantages Disadvantages
1) Conserve supply of ore.
2) Less litter.
3) Reduces a country’s bill.
4) Cheaper than extracting metal from its ore.
1) Purity of recycling is not high as pure metal.
2) Cost for collecting and transporting the metal is
high.
The liquid state
Melting
When a solid is heated, the particles gain heat energy which is converted to kinetic energy. The particles
vibrate more vigourously. The forces of attraction between the particles weaken. The solid changes to
liquid. The particles can now slide over each other and move throughout the liquid.
Freezing
When a liquid is cooled, the particles lose kinetic energy and they move more slowly. The forces of
attraction between them increase. Thus the particles become arranged in an orderly manner. The liquid
turns to a solid.
Vapourisation
When a liquid is heated, the particles gain heat energy which is converted to kinetic energy. The
particles move faster. The forces of attraction between them weaken. Some particles can escape as gas.
The process at which particles escape as gas is called evaporation. This occurs below b.p.
Boiling occurs at the b.p. All forces of attraction between the particles are broken. The particles are free
to move in any direction.
The energy required to change one mole of liquid to one mole of gas is called the enthalpy change of
vapourisation.
Condensation
When a vapour is cooled, the particles lose kinetic energy. So they move less quickly. They become
closer to each other and get attracted by strong forces of attraction. The particles can now move
together and throughout the liquid.

11. Vapour pressure
Liquids exert a vapour pressure. This is caused by molecules vapourising from the surface of the liquid
to become a gas (below the b.p). These molecules of vapour exert a pressure on the walls of the
container.
The vapour pressure will increase when the temperature increases because:
• the gas particles have more kinetic energy.
• the gas particles move faster, so are able to overcome intermolecular forces of attraction more easily.
The temperature at which the vapour pressure is equal to the atmospheric pressure is the b.p of the
liquid.