Give an account of existence of various elements and compounds.
Metals exist as atomic crystals and do not form molecules. Generally, metals and other elements like carbon and silicon do not have single molecular structure but consist of a very large indefinite number of atoms bonded together. A form of carbon bonded with sixty atoms is called buckminsterfullerence.
Non-metals exist as molecules containing one or more atoms. For example, argon exists as Ar and nitrogen as N2.
Compounds containing non-metals only exist as molecules. For example, compound of nitrogen and hydrogen is a ammonia molecule. Compound of carbon and oxygen is a carbon dioxide molecule.
Compounds containing metal and non-metal exist as ions. For example, compound of sodium and chlorine consists of positively charged sodium ions and negatively charged chloride ions.
