Don’t quote me on this but I think:
Magnesium: two valence electrons, 2 dots, 2 oxidation #
Sodium: one valence electron, one dot, +1 oxidation
Arsenic: five valence electrons, 5 dots, either -3,+3, or +5
Bromine: 7 valence electrons, 7 dots, either 1-,1*,5+
I hope this helps
