Video Transcript
What is the valence of a metal with
the electronic configuration 2,8,2?
An electronic configuration of
2,8,2 indicates that we have two electrons in the K shell, eight electrons in the L
shell, and two electrons in the M shell. We’ve been asked to determine the
valence of this metal. The valence is the number of
electrons that an atom gains, loses, or shares during a chemical reaction. Atoms gain, lose, or share
electrons to have a stable electronic configuration. This stable electronic
configuration corresponds to two electrons in the K shell and eight electrons in the
other shells, like the L and M shell.
One way this metal could attain a
stable electronic configuration is by gaining six electrons. These six electrons would fill the
M shell, giving the metal an electronic configuration 2,8,8. Or the metal could lose the two
electrons in the M shell, leaving it with the electronic configuration 2,8.
While both of these possibilities
end in a stable electronic configuration for the metal, it’s more likely that an
atom will gain or lose a small number of electrons than a larger number. So this atom will likely lose the
two electrons in the M shell. Since this metal loses two
electrons, that means it has a valence of two.
So the valence of a metal with the
electronic configuration 2,8,2 is two.
