2.7 - diamond & graphite

what are allotropes?

different structural forms of the same element in the same physical state

how are carbon atoms arranged in diamond?

they are covalently bonded to 4 carbon atoms (maximum) which makes diamond really hard

how are the carbon atoms arranged in graphite?

they are covalently bonded to 3 other carbon atoms and arranged in hexagons which form flat sheets

why is graphite soft?

because it forms layers of hexagonal sheets, they can slide over each other. this is also because the layers are only held together weakly

why can graphite conduct electricity?

as only 3 carbon atoms are covalently bonded, there is 1 delocalised electron which can conduct electricity and thermal energy