diamond and graphite

allotropes

different forms of the same element

diamond features

hard-many strong covalent bonds, macromolecular

high mp

bonded to 4 other carbon atoms

tetrahedral arrangement -109.5

no conduct electricity- no charged particles that can move

graphite features

conduct electricity- delocalised electrons between layers that can move and carry a charge, outer electron can become delocalised

high mp

layered structure with weak forces of attraction between layers, slide and break easily

types of crystalline structures

Ionic

Metals

macromolecular

molecular

describe what happens when a substance melts?

energy is taken in to overcome the forces

what happens when substances freeze

energy is released as forces are formed

subliming

solid to gas

summarise diamond

-hard

-high mp

-no conduct electricity

summarise graphite

-soft-weak van der waals forces between layers means it can slide across

-high mp

-conducts electricity-along planes of hexagons