Question

E asy method to learn atomic mass of first 20 elements

Answer 1

Explanation:

I m giving a general method,but this method is applicable till calcium

let the atomic no. be n

then for elements with even atomic no.

atomic mass =2n

for elements with odd atomic no.

atomic mass=2n+1

*note: this is not applicable for hydrogen (1u),nitrogen(14u), chlorine (35.5u),argon(40u)