why carbon can conduct electricity?

Question

metal can conduct electricity due to presence of free electrons but carbon should have no free electron in its structure.Why it can conduct electricity?

Answer 1

1) carbon should have no free electron in its structure.Why it can conduct electricity?
Ans: Carbon has two kind of structure. i)Diamond鑽石& ii)Graphite石墨

i)Diamond鑽石---
all carbon atoms are strongly bond tetrahedrally to form a giant covalent network. There is no free e- .
...........O
............|
...........O
........../...\
........O....O...如此類推...very very hard & very high boiling & melting point, Do not conduct electricity.

ii)Graphite石墨---
since there is weak intermolecular force between the layer, the layer can easily slide over one anther. There is free e- within the layer
*********************
:::::::::::::::::::::::::::::::<---------------free e-
...........**************************
:::::::::::::::::::::::::::::::::::::
***********************........如此類推..soft, conduct electricity at room temperature.

Answer 2

carbon 有一個formate 係graphite
佢用左3粒slectron 去form covalent bond with other carbon
由於係3個bond 佢成為左一個plane
最後個粒electron 就係plane 同plane之間自由游離
由於lee 粒electron 係free electron
所以it conduct electricity