What electron configuration makes an atom stable and not likely to react?

A noble gas electron configuration is the least reactive electron configuration.  A noble gas configuration is present when the valance electron shell is filled.  Since the goal of chemical reactions is to create a full valence shell atoms that already have a full valence shell would not react and would therefore be stable.

I hope this helps.  Let me know if anything is unclear or if you have any further questions.

Ibelieve it's celsius. hope this .