The numbers listed represent the number of electrons in the first, second, and third energy levels, respectively. on this basis, which of the following is an unstable or reactive atom? a) 2, 8, 8b) 2, 8c) 2d) 2, 8, 1

D

Explanation:

This is because one of its orbital shells is not filled – the one with 1 electron. This atom will, therefore, want to lose this electron – it takes less energy to do this than gain 7 electrons -- to achieve stable electron configuration. This makes this atom very reactive in a chemical reaction.  Usually orbital shells of atoms begin with an S orbital shell that is filled with 2 electrons then P (x,y,z) orbital shells filled with 6 electrons total. There are also higher energy f and d orbitals that each take a maximum 10 and 14 electrons respectively. An atom is stable if its orbitals are fully filled.  

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