AQA GCSE Combined Science Chemistry - Bonding, Structure and the properties of matter

What is ionic bonding?

A bond formed between a metal and a non-metal by transferring electrons.

What ions do metals form?

Positive ions (cations) – they lose electrons

What ions do non-metals form?

anions-negative ions

What holds ionic compounds together?

Electrostatic forces of attraction between oppositely charged ions.

What is the structure of an ionic compound?

A giant ionic lattice.

What are the properties of ionic compounds?

High melting/boiling points; conduct electricity when molten or in solution.

What is covalent bonding?

bonding between 2 non metals that share electrons

What are simple molecular substances?

Molecules made of a few atoms joined by covalent bonds.

What are the properties of simple molecules?

Low melting/boiling points; do not conduct electricity.

Why do simple molecules have low melting/boiling points?

They have weak intermolecular forces.

What are polymers?

Long chains of repeating covalently bonded molecules.

What are the properties of polymers?

Solid at room temperature; intermolecular forces are stronger than in small molecules.

What are giant covalent structures?

Solids where atoms are bonded by strong covalent bonds in a large network.

Give examples of giant covalent structures.

Diamond, graphite, silicon dioxide.

What are the properties of diamond?

Very hard, high melting point, does not conduct electricity.

What are the properties of graphite?

Soft/slippery (layers slide), high melting point, conducts electricity.

Why does graphite conduct electricity?

It has free (delocalised) electrons between layers.

What is graphene?

A single layer of graphite – one atom thick.

What are fullerenes?

Molecules made of carbon arranged in hexagons, pentagons, or both (e.g. buckyballs).

What is a nanotube?

A cylindrical fullerene with high strength and conductivity.

What is metallic bonding?

A bond between metal atoms involving a ‘sea’ of delocalised electrons.

Why are metals good conductors of electricity and heat?

Their delocalised electrons carry energy.

Why are metals malleable?

Layers of atoms can slide over each other.

What is an alloy?

a mix of metals to make it more strong

Why are alloys harder than pure metals?

Different sized atoms distort the layers, making them harder to slide.