1.as you move from left to right across a period, the number of valence electrons
-increases
-stays the same
-increases and then decreases
-decreases

2.compared with group 2a elements, group 64 elements have
-more atoms in the ground state
-more valence electrons
-more isotopes
-fewer valance electrons

3.which of the following group 7a elements is the most reactive?
-ci(chlorine
-i(iodine)
-f(fluorine)
-br(bromine)