1.43 explain the high melting and boiling points of substances with giant covalent structures in terms of the breaking of many strong covalent bonds

Giant covalent structures

Some substances are made up of millions of atoms covalently bonded together to form a giant structure. These substances have high melting and boiling points, because when melting or boiling it, you are not separating inter-molecular bonds between the atoms, but the inter-molecular bonds that keep the molecule together. There are a lot of these, therefore they have high melting and boiling points.