Question #c75c4

1 Answer
May 28, 2015

It depends on which energy state an excited electron enters.

If the electron enters a higher energy shell, then the atom's valency changes. Recall that valency in simple context can be defined as the total number of electrons in the outermost (occupied) shell.
The valency may also change if the electron leaves the atom altogether by overcoming the attractive nuclear forces (only by gaining the required amount of energy).
Be careful, the valency will not change if the electron jumps to a higher energy sub shell or orbital in the same shell .

A thorough understanding of electronic configuration will help you understand this clearly.