The atomic number of hydrogen is 1 and that of helium is 2. Why is hydrogen(a non-metal) placed in the first group and helium in the 18th group?
Hydrogen can be placed in group 1 and group 17 of periodic table. Why?
Although there's anamoly with respect to position of hydrogen. But it is placed in group 1. Why in group 1 and why nin in group 17?