Explain in terms of bonding, why graphite is soft and diamonds are hard?

1 Answer
May 3, 2018

A diamond has a stronger molecular geometric shape than graphite.

Explanation:

Inside of diamonds, each carbon atom is covalently bonded to four other carbon diamonds in a tetrahedral shape. A lot of energy is required to break these covalent bonds since there are a ton of these bonds. In theory, graphite would be the same way, but it only bonds to three other carbon diamonds in a honeycomb type lattice. This just basically means layers, which can rub off, such as in writing with a graphite pencil.

So in conclusion, diamond is only harder due to its structural shape, (look into the VSEPR theory if you want to learn more about how the way a molecule's shape helps its bond strength).