Explanation:
H is hydrogen and Na is sodium.
Hydrogen is the first element of the periodic table. Its atomic no is 1. Its atomic weight is 1.008. Its electronic configuration is 1s¹.
Na is hydrogen. It lies at 3rd period and 1st group. Its atomic number is 11. Its atomic weight is 22.989769 u. Its electronic configuration is 2,8,1.
