GCSE Chemistry, 4.2- Structure and Bonding.

Describe two limitation of particle model. [2 marks]

• Not showing the force.

• Not showing particle have different shape.

Hydrogen is one example of small covalent molecule.

Explain why hydrogen has a low boiling point. [2 marks]

• Has a weak intermolecular force.

• Not require a lot of energy to break the intermolecular force.

Explain why sodium chloride has a high melting point. [3 marks]

• Giant ionic lattice.

• Strong electrostatic forces of attraction between oppositely charged ions.

• large amounts of energy are needed to break the force.

Explain why sodium chloride only conduct electricity when melted or dissolved in water. [2 marks]

• Ions can move.

• Carry charges.

Poly(ethene) is a example of polymer.
Explain why poly(ethene) is a solid in room temperature. [4 marks]

• (Because) Strong intermolecular force of attraction between polymer molecule.

• (So) Require great deal of energy to break it.

• (So) High melting points.

• (So) Not enough energy to break the forces in room temperatures.

Describe the structure of diamond. [2 marks]

• Each carbon atom form 4 covalent bonds with other carbon atoms.

• Giant covalent structure.

Two key properties of diamonds are high boiling point and does not conduct electricity.
Explain how the structure of a diamond is related to both properties. [4 marks]

• Giant covalent structure.

• (So) it require great deal of energy to break millions of covalent bonds.

• All outer electron is in covalent bonds.

• (So) there are no free electron.

Describe the structure of buckminsterfullerene. [1 mark]

Hollow spherical shape.

State two uses of fullerenes. [2 marks]

• Catalyst

• Delivery drug

Explain why graphite is soft and slippery conductor. [3 marks]

• Layered structure of hexagonal rings.

• Weak intermolecular forces between layers

• (So) the layers can slide over each other.

Explain why graphite is good electrical conductor. [3 marks]

• Only three electrons per carbon atom used in covalent bonds.

• One delocalised electron per carbon atom.

• delocalised electron can move around and carry charge.

Give three type of particle. [3 marks]

• Course particle.

• Fine particle.

• Nanoparticles.

Give two uses of nanoparticle. [2 marks]

• Medicine.

• Catalyst.

Explain why alloys are harder than pure metals.

[3 marks]

• The atom have different sizes.

• The layers are distorted.

• The layers slide over each other less easily.

Describe how metals conduct electricity. [3 marks]

• Metal have delocalised electrons.

• The electrons carry electrical charge.

• The electrons move through the metal.