1.41 understand that substances with simple molecular structures are gases or liquids, or solids with low melting points

Simple molecular substances

Both elements and compounds can exist as simple molecular substances.

Simple molecular substances usually have low melting and boiling points.

This is because the forces of attraction between oppositely charged ions, (i.e. ionic bonds) and therefore very little energy is required to overcome them.

Although, when simple molecular substances change state, the covalent bonds between the atoms are not usually broken. Covalent bonds are strong compared to the forces of attraction between the molecules.