1st period ( Period 1 ) : 2 elements
2nd period ( Period 2 ) : 8 elements
3rd period ( Period 3 ) : 8 elements
Explanation:
Accordingly to the periodic table, we have the following elements in period 1, 2 and 3 respectively:
Period 1: Hydrogen, H and Helium, He
Period 2: Lithium (Li), Berrylium (Be), Boron (B), Carbon (C), Nitrogen (N), Oxygen (O), Fluorine (F), Neon (Ne)
Period 3: Sodium (Na), Magnesium (Mg), Aluminum (Al), Silicon (Si), Phosphorus (P), Sulphur (S), Chlorine (Cl), Argon (Ar)
