Explain the classification of matter based on chemical composition.

Explanation

Chemical Classification : Pure substances are composed of simple stoms or moelcules. They are further classified as elements and compounds.
(a) Element : `ast` An element consits of only one type of atom.
`ast` Element can exist as monoatomic or polyatomic units. The polyatomic elements are called molecules.
Eg : Monatomic unit - Gold (Au), Copper
(Cu), Polyatomic unit - Hydrogen `(H_2)`
(b) Compound : Compounds are made up of molecules which contain two or more atoms of different elements.
Eg: Carbon dioxide `(CO_2)`, Glucose `(C_6H_12O_6)`.