Question

How many valance electrons do atoms in group 1 group 2 and groups 15 to 17 have?

Answer 1

group 1 has one valence electron
group 2 has two valence electrons
group 15 has one valence electron
group 16 has two valence electrons
group 17 has three valence electrons
& at last group 18 contains inert gases so no valence electron
hope it'll help

Answer 2

Following this rule: Elements in group 1 have one valence electron; elements in group 2 have two valence electrons; elements in group 13 have three valence electrons; elements in group 14 have four valence electrons; and so forth up to group 18.