18. when is an atom unlikely to react and form chemical bonds?

An atom is unlikely to react when it's stable. That's when it's shell is complete. Due to the completion of the shell, no other electron can combine through any form of bonding!
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Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.