Bonding, Structure and properties of matter - entire aqa spec

What are the three main types of chemical bonding?

Ionic, covalent, and metallic bonding.

What determines the type of bonding between atoms?

The elements involved — metals, non-metals, or both.

What happens in ionic bonding?

Electrons are transferred from metal atoms to non-metal atoms, forming positive and negative ions.

What happens in covalent bonding?

Non-metal atoms share pairs of electrons.

What happens in metallic bonding?

Metal atoms share delocalised electrons that move freely among positive ions.

Which types of elements form ionic bonds?

Metals and non-metals.

What do metal atoms form in ionic bonding?

Positive ions (cations).

What do non-metal atoms form in ionic bonding?

Negative ions (anions).

What holds ions together in an ionic compound?

Strong electrostatic forces of attraction between oppositely charged ions.

What is the structure of an ionic compound?

A giant ionic lattice.

Why do ionic compounds have high melting and boiling points?

Because a lot of energy is needed to overcome strong ionic bonds.

Do ionic compounds conduct electricity when solid?

No, because ions are fixed in place and cannot move.

Do ionic compounds conduct electricity when molten or dissolved in water?

Yes, because ions are free to move and carry charge.

Why are many ionic compounds soluble in water?

Because water molecules separate and surround the ions.

Which elements form covalent bonds?

Non-metals.

What holds covalently bonded atoms together?

Shared pairs of electrons between atoms.

What are simple molecular substances?

Molecules made up of a small number of atoms joined by covalent bonds.

Give examples of simple molecular substances.

H2, O2, H2O, CO2, CH_4.

What forces exist between simple molecules?

Weak intermolecular forces.

Why do simple molecular substances have low melting and boiling points?

Because weak intermolecular forces require little energy to overcome.

Do simple molecular substances conduct electricity?

No, because they have no charged particles that can move.

What are giant covalent structures?

Huge 3D networks of atoms joined by covalent bonds.

Give examples of giant covalent structures.

Diamond, graphite, silicon dioxide (SiO_2).

Why do giant covalent structures have high melting points?

Because many strong covalent bonds must be broken to melt them.

Describe the structure and properties of diamond.

Each carbon atom forms four bonds; very hard; high melting point; does not conduct electricity.

Describe the structure and properties of graphite.

Each carbon atom forms three bonds, leaving one delocalised electron; arranged in layers that can slide; conducts electricity; soft and slippery.

What is graphene?

A single layer of graphite — one atom thick, strong, light, and conducts electricity.

What are fullerenes?

Molecules of carbon shaped like hollow spheres or tubes (e.g., buckminsterfullerene, carbon nanotubes).

What are uses of fullerenes and nanotubes?

Drug delivery, lubricants, catalysts, and high-strength materials.

What is metallic bonding?

The attraction between positive metal ions and delocalised electrons.

What structure do metals have?

Giant structures of positive ions surrounded by a sea of delocalised electrons.

Why do metals conduct electricity and heat?

Because delocalised electrons can move freely through the structure.

Why are metals malleable and ductile?

Layers of atoms can slide over each other while metallic bonding remains.

What is an alloy?

A mixture of metals (or a metal with another element).

Why are alloys harder than pure metals?

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

Give examples of alloys and their uses.

Steel – construction; Brass – instruments; Bronze – statues and medals; Duralumin – aircraft.

What are the three states of matter?

Solid, liquid, and gas.

Describe particles in a solid.

Fixed positions, closely packed, vibrate in place.

Describe particles in a liquid.

Close together, can move past each other randomly.

Describe particles in a gas.

Far apart, move freely and quickly in all directions.

What happens when a solid melts?

Particles gain energy, vibrate faster, and overcome some forces holding them in place.

What happens when a liquid boils?

Particles gain enough energy to break all forces between them and form a gas.

What happens when a gas condenses or freezes?

Particles lose energy and move closer together.

What is the particle model used for?

To explain changes of state and properties of materials.

What are limitations of the particle model?

It doesn’t show forces or particle movement accurately — particles aren’t solid spheres.

What is melting point?

The temperature where a solid turns to a liquid.

What is boiling point?

The temperature where a liquid turns to a gas.

What type of change is a change of state?

A physical change — no new substance is formed.

What determines melting and boiling points?

The strength of forces between particles.

What are nanoparticles?

Very small particles between 1–100 nanometres in size.

Why are nanoparticles useful?

They have a very large surface area to volume ratio.

Give examples of nanoparticle uses.

Catalysts, drug delivery, sunscreens, and cosmetics.

What are possible risks of nanoparticles?

Unknown effects on health or the environment due