why carbon can conduct electricity?

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.

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