Explain the structure of diamond and graphite.

(N/A) $1$. Diamond and graphite are examples of covalent or network solids. In these,atoms are held together by strong,directional covalent bonds,forming a giant molecular structure.
$2$. Diamond: Each carbon atom is $sp^3$ hybridized and bonded to four other carbon atoms in a tetrahedral geometry. This creates a rigid,three-dimensional network,making diamond the hardest natural substance with a very high melting point. It is an electrical insulator because all valence electrons are involved in bonding.
$3$. Graphite: Each carbon atom is $sp^2$ hybridized and bonded to three other carbon atoms in the same plane,forming hexagonal rings in layers. The fourth valence electron is delocalized between the layers,allowing graphite to conduct electricity. The layers are held by weak van der Waals forces,allowing them to slide over each other,which makes graphite soft and a good lubricant.