Dial up each and take a look at adding or subtracting electrons to make the ion isoelectronic with a noble gas.
don't think Zr^4+ will do it.
http://www.webelements.com/
Determine which ions have noble-gas configurations:
Cd2+
Ru3+
P3−
As3−
Ag+
Zr4+
Thanks for any help. (I tried As3- and Zr4+, but that was wrong, so maybe i'm just missing one.
2 answers
For anyone looking for the answer for mastering chemistry, it’s As3- Zr4+ and P3-
1 answer