states of matter

Question 1

What kinetic assumptions are made

when dealing with an ideal gas?

Answer 1

1. The gas contains a large number of molecules moving in random
   directions at random speeds.
2. Electrostatic forces between molecules is negligible, except during
   collisions.
3. Collisions are perfectly elastic.
4. Time of collisions between molecules is negligible compared to time
   between collisions.
5. The molecules of a gas occupy negligible volume compared to the total
   volume of the gas.

Question 1

What kinetic assumptions are made

when dealing with an ideal gas?

Answer 1

1. The gas contains a large number of molecules moving in random
   directions at random speeds.
2. Electrostatic forces between molecules is negligible, except during
   collisions.
3. Collisions are perfectly elastic.
4. Time of collisions between molecules is negligible compared to time
   between collisions.
5. The molecules of a gas occupy negligible volume compared to the total
   volume of the gas.

Question 2

What are the conditions necessary for a gas to

approach ideal behaviour?

Answer 2

● Low pressure

● High temperature

Question 3

What are the limitations of an ideal gas

at very low temperatures and very high pressures?

Answer 3

● Intermolecular forces are no longer
negligible and have to be considered.
● Molecular size is also no longer
negligible and has to be considered.

Question 4

What is the ideal gas equation?

Answer 4

pV = nRT
p - pressure (Pa)
V - volume (m3)
n - number of moles (mol)
R - gas constant (8.314 J K-1 mol-1)
T - temperature (K)

Question 6

The ideal gas equation can be used with
which other equation to find molecular
mass?

Answer 6

M = m/n
M - molecular mass
n - number of moles (mol)
m - mass (g)

Question 7

Use the kinetic-molecular model to describe the

liquid state

Answer 7

●  Particles are close together but 
   not regularly arranged.
●  Particles have a little more kinetic 
   energy than in a solid.
●  There are fewer electrostatic 
   forces between particles than in a 
   solid, allowing particles to move  past each other and flow.

Question 8

In terms of the kinetic-molecular model,

what happens during melting?

Answer 8

● Solid → Liquid
● Increasing the temperature of the surroundings
causes particles to absorb energy meaning they gain
more kinetic energy.
● Eventually, the particles gain enough energy to
disrupt the regular arrangement and become a liquid.

Question 9

How do particles act during vaporisation?

Answer 9

● Liquid → Gas
● Heat energy causes particles in a liquid to
move fast enough to break all forces of
attraction between them and become a gas.

Question 10

What is vapour pressure?

Answer 10

When a liquid evaporates in a closed
container, the gaseous particles move around
above the liquid. When these particles collide
with the walls of the container, they exert a
pressure called the vapour pressure.

Question 11

Describe the structure of a solid ionic compound

Answer 11

● Regular, repeating 
  arrangement (lattice).
● Caused by the electrostatic 
  attraction between the 
  oppositely charged ions.

Question 12

Describe the lattice structure of iodine

Answer 12

● Iodine is an example of a simple
molecular lattice.

● Iodine, I2 molecules form a larger 
  structure due to intermolecular forces 
  (Van der Waals Forces) between 
  molecules.
● The structure is described as face 
  centred cubic.

Question 13

What is an allotrope?

Answer 13

Allotropes are different physical forms of

an element in the same state.

Question 14

Describe the structure of a fullerene

Answer 14

Lattice structure
E.g. a buckminsterfullerene

(C60) is a molecule consisting of 60 carbon atoms arranged
in pentagons and hexagons.

Question 15

What is a nanotube?

Answer 15

A graphene sheet rolled up
into a tube (single sheet of
carbon atoms covalently

bonded together)

Question 16

Describe the structure of diamond

Answer 16

● Giant covalent lattice.
● Each carbon atom is covalently bonded to four
other carbon atoms.
● Extremely strong structure.
● Bond shape and angle around each carbon:
Tetrahedral, 109.5°.

Question 17

Describe the structure of graphite

Answer 17

● Giant covalent lattice.
 ● Made from layers of carbon arranged in 
   hexagonal rings.
 ● There are weak london forces between 
   layers.
 ● Each carbon atom bonds covalently to 3 
   other carbon atoms.
 ● One delocalised electron per carbon.

Question 18

Describe the structure of graphene

Answer 18

● Giant covalent lattice.
● Single layer of graphite.
● Each carbon atom is bonded to 
  3 other carbon atoms to create 
  a hexagonal ringed structure.
● One delocalised electron per 
  carbon.

Question 19

Describe the structure of silicon(IV) oxide

Answer 19

Describe the structure of silicon(IV) oxide
● Similar 3D structure to diamond.
● Silicon and oxygen atoms covalently
bonded together.

Question 20

Describe the structure of ice

Answer 20

Describe the structure of ice
● Open lattice structure.
● Hydrogen bonds hold water
molecules apart in hexagonal rings.

Question 21

Describe the structure of a metal

(e.g. copper)

Answer 21

Giant metallic lattice with positive ions packed
closely together with delocalised electrons.
In copper, each atom is surrounded by 12
other copper atoms.

Question 22

What does a diagram of metallic bonding look like?

Answer 22

● Positive charges =
ions
● Negative charges =
electrons

Question 23

What is a finite resource?

Answer 23

A resource that is used up faster than it
is replaced. This resource will run out if it
is continually used.

Question 24

Why is recycling important?

Answer 24

● To conserve finite resources for as long as possible
by reducing the rate at which the are used.
● Reduces greenhouse gas emissions (which cause
global warming).
● May reduce costs and other environmental impacts
of a material.

Question 25

How does hydrogen bonding affect the
boiling and melting points of a
substance?

Answer 25

Hydrogen bonding is the strongest type of
intermolecular bond and hence requires a lot of
energy to overcome when boiling/ melting a
substance. As a result, structures that contain
hydrogen bonding often have higher melting and
boiling points than expected.

Question 26

How does hydrogen bonding affect the viscosity of a

substance?

Answer 26

Hydrogen bonds increase viscosity of a
substance because these bonds (as well
as any other intermolecular forces) make
the substance more resistant to flow.

Question 27

How does hydrogen bonding create

surface tension in water?

Answer 27

Hydrogen bonding increases surface tension.
Water molecules at the surface of the liquid are
attracted more strongly to other water molecules
around them than the layers of water molecules
below, creating tension at the surface of the liquid.

Question 28

What does boiling point suggest about structure and

bonding?

Answer 28

A high boiling point indicates a giant
structure (ionic metallic or giant covalent).
A low boiling point indicates simple
molecules (or atoms for noble gases).

Question 29

What does solubility suggest about structure and

bonding?

Answer 29

Compounds that are soluble in water tend to be
ionic.
If a soluble compound has a low boiling point, it
may be small and very polar or able to form
hydrogen bonds.

Question 30

What does electrical conductivity suggest about

structure and bonding?

Answer 30

If a solid substance conducts electricity, it is
likely to be a metal, graphene or graphite.
If a substance only conducts when molten or
dissolved, it is an ionic compound.

Question 31

What do appearance/ malleability suggest about

structure and bonding?

Answer 31

If a substance is brittle, it is likely to be
ionic or giant covalent.
If a substance is shiny, malleable and
ductile, it is likely to be a metal.