Question

No liquid ionic compound are known,but many of the known covalent compound are liquids and some are gases.account for these differences

Answer 1

The forces of attraction between particles (ions) of ionic compounds are very strong, and they exist as crystal lattices. Thus they have very high melting points and most of these compounds exist as solids at room temperature.

Eg: NaCl sodium chloride

however, for covalent compounds, their particles are held together by weak van der wall's forces and thus have low melting points. So, many of them exist as liquids at room temperature.

Eg: C8H18 octane