Question

why do some element exist as moleclues and same as atom​

Answer 1

Explanation:

Some atoms are same as molecules because there molecules have the same atoms. For example oxygen molecules have formula O2, which means it consists only of 2 oxygen atoms.

Answer 2

Explanation:

The only elements which occur naturally as diatomic molecules are hydrogen, nitrogen, oxygen, plus all the halogens, fluorine, chlorine, bromine and iodine. These seven elements normally exist as the molecular species H2, N2,O2, F2, Cl2, Br2 and I2 respectively rather than in the form of single atoms.