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




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




Potassium's oxidation number is +1, oxidation numbers are just hypothetical charges that an atom would have if the compound is ionic(This is not always the case),but it's useful for keeping track of electrons. In this case it means that the Potassium atom losses one electron when forming compounds. Chemical elements are arranged in groups where the number with the letter(e.g.,1A,2A,3B,etc.) shows how many valence electrons an atom has, Group 1A(The first column to the left on the periodic table) has one electron on its valence shell so it tends to lose that electron in order to get a noble gas's electronic configuration and that makes sense given Potassium's oxidation number.
[![There's the periodic table with the arrangement I'm talking about](https://i.stack.imgur.com/QACcf.png)](https://i.stack.imgur.com/QACcf.png)


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