# Why does zinc react while its outermost suborbital is full?

Why does zinc lose electrons while its outermost configuration is 4$\rm{s}^2$ 3$\rm{d}^{10}$ both outermost suborbital are full.

Why does it react or lose electrons?

You could ask the same question about the alkali earth metals with their $\rm{s}^2$ valence shell. While there is an energy cost to removing electrons, in a spontaneous reaction (e.g. $\ce{Cu^2+_{(aq)} + Zn_{(s)} -> Cu_{(s)} + Zn^2+_{(aq)}}$) there will be a compensatory transfer of energy elsewhere (like the reduction and deposition of $\ce{Cu^2+}$) which leads to a more stable overall system.
Zinc has quite a stable configuration, but that does not mean it does not want to attain noble gas configuration. You should also observe that $Zn^{++}$ is more stable that ground state of Zn. This is due to the fact that both $e^-$ from $4s^2$ orbital are removed and the Zn ion has a fully-filled d-orbital, which is much more stable than the ground state configuration. Thus Zn reacts to get more stability provided by the fully-filled d-orbital.
• FYI: Zn has positive ionization energy, therefore $\ce{Zn^{2+}}$ is less stable than $\ce{Zn^0}$ – permeakra Aug 8 '16 at 16:10