06. Properties of giant molecular structures (macromolecules)

What are diamond and graphite?

Different crystalline allotropes

What are allotropes?

Different forms / structure of the same element in the same state

What kind of structure does diamond have? What is this governed by?

Cubic structure governed by a tetrahedron bond angle

Describe carbons in diamond?

Each carbon atom bonds to 4 other carbon atoms whose centres are all corners of a tetrahedron

What are properties of diamond?

High MPT and does not conducts electricity

Why does diamond have a high melting point?

Strong covalent bonds -> All bonds need to be broken for melting

Why does diamond not conduct electricity?

No free electrons or ions to move and carry charge when potential difference is applied

What kind of structure does graphite have?

2D consisting of hexagonal layers of carbon with large interplanar distance

Describe carbon in graphite?

Each carbon atom covalently bonded to 3 other carbons

What is the bond angle in graphite?

120 degrees

What forces does graphite have?

Weak intermolecular VDW between the planes

What properties does graphite have?

Conducts electricity and high MPT

Why can graphite conduct electricity?

Delocalised electrons free to move and carry charge when potential difference is applied

Why does graphite have a high melting point?

Many strong covalent bonds must be broken

Why is graphite an industrial lubricant?

Easy to split 1 layer from others as they have weak VDW

Describe conduction of electricity by graphite?

Only in direction of plane

How are graphite layers layered?

Weak VDW between so they slide