both Graphite and diamond are giant covalent structures they both have have high melting points and are insoluble due to their complex structures Graphite: Each carbon is bonded to 3 other carbon atoms, so had a 'spare' electron. This means that graphite is able to conduct current/ electricity are the free electron can carry current arranged in interconnected hexagonal layer Because it is arranged in layers, it is malleable as these layer are able to slide over each other due to the weak bonds between them Diamond:each carbons is bonded to 4 other carbons atomsit therefore has no spare electron, and so is unable to conduct electricity, as no free-moving electrons are available to carry current. It is very hard, as each of the 4 covalent bonds must be broken in order for it to change state.