An atom with 2 valence electrons forms a ion.
+1
+2
-2
0 -1

as atom has two valence electron it can lose two electron with +2 ion

Explanation:

they it depends on if one believes about radioactivity, they make a geiger counter beep but maybe it was going to beep anyway electronics do wierd things all the time or it was programmed to beep near certain metals.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).