Question

What element’s valence electrons are located in 5s^25p^5?

Answer 1

That would be iodine.

Explanation:

If you consider only the main groups of elements (meaning columns 1 and 2, and 13 through 18), the row in which you find the element matches the value of `n` in the electron configuration - 5 in this case. So, we go to the fifth row.

Next, since there are seven valence electron in the notation you wrote, you move to the seventh element in these main groups (omit the transition metals!) and you arrive at iodine.

This pattern works for all elements in the main groups.