AQA Chemistry GCSE Topic 2 - Bonding, Structure and the Properties of Matter

Question 1

What is ionic bonding?

Answer 1

• Ionic bonding is the electrostatic attraction between positive and negative ions.
• formed from metals combined with non-metals
• ionic bonds transfer electrons from one atom to another to achieve a full outer shell

Question 2

How are ionic compounds

held together?

Answer 2

-They are held together in a giant lattice.
-Held together by strong electrostatic forces of attraction between oppositely
charged ions
-It’s a regular structure that extends in all directions in a substance.

Question 3

State properties of ionic substances - boiling and melting points

Answer 3

High melting and boiling point because strong electrostatic forces between oppositely charged ions require a great deal of heat energy to break

Question 4

State properties of ionic substances - conductivity

Answer 4

Do not conduct electricity when solid this is because the ions are held together by strong electrostatic forces of attraction In a fixed position

Question 5

State properties of ionic substances - conductivity when liquid

Answer 5

ions can conduct electricity when melted or dissolved in water because the ions are free to move

Question 6

What is a covalent bond?

Answer 6

• atoms share a pair of electrons
• there is electrostatic attraction between nucleus of atoms and the shared pair of electrons
• occurs in non-metals and non-metals

Question 7

types of covalent bonds

Answer 7

simple molecules
large molecules
giant covalent

Question 8

properties of simple

molecular covalent substances-conductivity

Answer 8

do not conduct electricity because molecules do not have an overall electric charge so no free ions

Question 9

properties of simple

molecular covalent substances-boiling and melting points

Answer 9

low melting and boiling points

Question 10

properties of simple

molecular covalent substances-state

Answer 10

as the temperature increases the vibration of the molecules increases at a certain point the vibration is strong enough to break the intermolecular forces at this point turn into a gas

gases or liquid in room temperature this id due to the weak intermolecular forces

Question 11

properties of simple

molecular covalent substances-forces

Answer 11

the forces of attraction between these molecules are weak

Question 12

How do intermolecular forces change as the mass/size of the molecule increases?

Answer 12

They increase.

That causes melting/boiling points to increase as well (more energy needed to overcome these forces).

Question 13

examples of simple covalent

Answer 13

small molecules e.g. HCl,

H2 O2 Cl2 NH3 CH4

Question 14

example of very large molecules,

Answer 14

polymers.
-Atoms in the polymer molecules are linked to other atoms by strong covalent
bonds
- Intermolecular forces between polymer molecules are relatively strong and so
these substances are solids at room temperature

Question 15

What are

thermosoftening polymers?

Answer 15

type of polymers; they melt/soften when
heated. There are no bonds between polymer chains. Strong intermolecular forces
ensure that the structure is solid at room temperature. These forces are overcome with heating - polymer melts.

Question 16

What are giant covalent

substances? Give examples

Answer 16

• atoms covalently bonded together in a giant lattice.
• High melting/boiling points - strong covalent bonds.
• Mostly don’t conduct electricity (no delocalised electrons)
• Diamond, graphite, silicon dioxide.

Question 17

What is metallic bonding?

Answer 17

Forces of attraction between delocalised electrons and nuclei of metal ions.
-occurs in metallic elements and alloys metals and metals

Question 18

properties of simple

molecular metallic bonds-structure

Answer 18

• Metals consist of giant structures of atoms arranged in a regular pattern.
• The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
• The sharing of delocalised electrons gives rise to strong metallic bonds
• metallic bonds are strong electrostatic attraction between positive metal ions and delocalised electron.

Question 19

properties of metallic bonds -boiling and melting points

Answer 19

high melting and boiling points because the electrostatic forces between the metal atom and delocalised sea of electron are very strong so need lots of energy to break

Question 20

properties of metallic bonds - conductivity

Answer 20

good conductor of heat and electricity because the delocalised electrons can carry electrical currents through the whole structure

Question 21

Describe the properties of metals

Answer 21

-High melting/boiling points (strong forces of attraction)
- Good conductors of heat and electricity (delocalised electrons)
- Malleable, soft (layers of atoms can slide over each other whilst maintaining
the attraction forces)
-Good conductors of electricity because the delocalised electrons in the metal
carry electrical charge through the metal
- Good conductors of thermal energy because energy is transferred by the
delocalised electrons

Question 22

What are alloys?

Answer 22

mixtures of metal with other elements, usually metal

Question 23

Why are they harder than pure

metals?

Answer 23

different sizes of atoms distort the layers, so they can’t slide over each other,
therefore alloys are harder than pure metals

Question 24

Describe and explain the

properties of allotropes of carbon-diamond

Answer 24

-formed from the element carbon
-each carbon is joined to 4 other carbons covalently.
very hard (Strong bonds)
- very high melting point (strong bonds)
- does not conduct (no delocalised electrons)

Question 25

Describe and explain the

properties of allotropes of carbon-graphite

Answer 25

-formed from the element carbon
-each carbon is covalently bonded to 3 other carbons, forming
layers of hexagonal rings which have no covalent bonds between the layers.
-The layers can slide over each other due to no covalent bonds between layers
-weak intermolecular forces. Meaning that graphite is soft and slippery.
-conduct thermal and electricity due to one delocalised electron per each carbon atom

Question 26

Fullerenes

Answer 26

–Molecules of carbon atoms with hollow shapes
– They are based on hexagonal rings of carbon atoms, but they may also
contain rings with five or seven carbon atoms
– The first fullerene to be discovered was Buckminsterfullerene (C60),
which has a spherical shape

Question 27

Nanotubes

Answer 27

Cylindrical fullerenes with very high length to diameter ratios
Their properties make them useful for nanotechnology, electronics
and materials

Question 28

uses of fullerenes

Answer 28

• pharmaceutical delivery
• lubricants
• catalysts

Question 29

Graphene

Answer 29

• a single layer of graphite
  -graphene is very strong because atoms within its layers are very
  tightly bonded

Question 30

What are the limitations of

the simple model?

Answer 30

• there are no forces of attraction
• all particles are shown as solid
• molecules and ions are solid spheres – this is not true

Question 31

What does the amount of energy
needed to change state from solid
to liquid or liquid to gas depend on?

Answer 31

-The strength of the forces between the particles of the substance.
-The nature of the particles involved depends on the type of bonding and
the structure of the substance.
-The stronger the forces between the particles
the higher the melting point and boiling point of the substance

Question 32

State the uses of nanoparticles

Answer 32

-Medicine (drug delivery systems)
- Electronics
- Deodorants
- Sun creams (better skin coverage and more effective protection
against cell damage)