# Group of Potassium and It's Oxidation Number

One of the questions I got wrong on a chemistry Kahoot question was

(1) Potassium is in group $1$, what is its oxidation number?

(a) -1

(b) +1

(c) +2

(d) -2

I don't remember what an "oxidation number" is... And what do they mean by group $1$? I don't quite remember learning that.

• All about potassium at Wikipedia en.wikipedia.org/wiki/Potassium Here is link to Wikipedia article on the periodic table. Notice group numbers along top of first figure. en.wikipedia.org/wiki/Periodic_table – MaxW Sep 29 '16 at 22:53
• Hm... Our teacher said that the number above was the number of valence electrons the elements had. (Paying only attention to the units place)... So a group number just tells you the number of electrons in the outer shell? – Frank Sep 29 '16 at 22:54