This means that each carbon atom has a 'spare' electron (as carbon has four outer electrons) which is delocalised between layers of carbon atoms. These layers can slide over each other, so graphite is much softer than diamond.

What makes graphite soft?

We can clearly notice that graphite is less dense as compared to diamond which makes it soft and slippery. ... The carbon atoms in graphite appear to bond with weaker intermolecular forces, allowing the layers to move over one another. The weak intermolecular forces are known as the weak Van der Waals forces.

Why is graphite soft and slippery?

Graphite is soft and slippery because its carbon atoms are bound together by weak bonds known as Van der Waal forces. The bonds that connect the carbon atoms in graphite are very weak, so they are easily broken, which makes graphite seem soft and slippery.