structure and bonding - giant covalent structures, carbon allotropes, nanotech

What does graphite and diamond have in common?

They are both made of pure carbon

What are allotropes?

Different forms of the same element, with atoms arranged differently causing very different physical qualities.

Are the boiling points of graphite and diamond high or low? Why?

They have high boiling points because they both have strong covalent bonds within them.

What makes diamond so hard?

The fact there are 4 bonds to the carbon in the structure, and the fact it is a 3D structure.

What makes graphite so soft?

The fact they are made of hexagonal layers bonded by WIMFs. They are slippery and can slide over each other easily.

Can diamond or graphite conduct electricity? Why?

Diamond has no free electrons, so it can't conduct electricity. On the other hand, graphite has one free electron, which means it can conduct electricity.

What do dotted lines on a ball and stick model represent?

Weak intermolecular forces (WIMFs)

What do strong white lines on a ball and stick model represent?

Strong covalent bonds

How are atoms arranged in a giant covalent structure?

the ATOMS (NOT MOLECULES) are arranged in a giant lattice pattern.

What is a giant covalent structure?

A substance with atoms joined by covalent bonds in a continuous network

What are two other allotropes of carbon besides diamond and graphite?

Fullerenes (buckyballs), nanotubes and graphene.

Describe a possible use and also the shape of buckyballs.

Made up of pentagons and hexagons in a spherical shape, and can potentially be used as a lubricant in machinery as it is spherical. They could also be used as a way to contain drug molecules so that they would be targeted/slowly released in the body

Describe the shape and possible uses of nanotubes.

Made of a sheet of hexagons rolled into a cylindrical shape, nanotubes can be used in various applications including reinforcing materials (due to its high tensile strength), conducting electricity (as it has delocalised electrons), and in nanotechnology for drug delivery.

What is the size of nanoparticles

Nanoparticles typically range from 1 to 100 nanometers.

Why do nanoparticles behave so differently than to how a ‘bulk material’ of the element would?

Because they have a much higher surface area to volume ratio

Name some uses of nanoparticles

In sunscreen: Often use ZnO TO Absorb harmful UV radiation, and this means better skin coverage and that it is colourless/clear

In clothing: Silver nanoparticles prevent the build up of unpleasant odours

Why are there some concerns about the use of nanoparticles?

Because if nanoparticles behave differently to a bulk material, it is reasonable to assume that they may have harmful effects. They also have the potential to penetrate cell membranes