because hydrogen has one valence electron and 1 energy level thats why is group 1 period 1
Answered by
jerichorayel
In terms on the periodic trend, hydrogen doesn't fit in the first group since the elements falling under the first group are alkali metals. However, if we try to count the number of electron/s in the valence shell, hydrogen atom has its only electron on the s orbital. Elements on group 17 have valence number of 7.
