Question

What is the oxidation number of potassium?

Answer 1

Potassium, with the symbol K and the atomic number $19$, is a chemical element. Potassium is an alkali metal, and all have a single valence electron in the outer electron shell that can be quickly extracted to form a positive-charged ion – a cation – that can interact with anions to form salts.

Complete answer:
Potassium is the element of the group $1$ and period $4$. Since its atomic number is $19$, so the electrons per shell is $2,8,8,1$. Since, there is only one electron in the outer shell of potassium, so we can say that potassium can release only a single electron from its outer shell easily.
In simple terms, the oxidation number is the number assigned to the elements in a chemical mixture. The oxidation number is the total number of electrons that atoms in a molecule can share, lose, or gain when forming chemical bonds with atoms of another substance.
When a potassium element releases an electron, one positive charge is added to it. It is written as –
$K(s) \to {K^ + } + {e^ - }$
Now, this positively charged potassium ion combines with different negatively charged ion to form salt. Some examples of compound forms by reacting with potassium ion are –
$\ {K^ + } + C{l^ - } \to KCl \\\ {K^ + } + O{H^ - } \to KOH \\\ \$
So, by this electron releasing theory, we can see that the oxidation number of potassium is $+ 1$. It means it can release one electron from its outer shell.

Note:
Larger than three oxidation states, whether positive or negative, are virtually impossible. Group I, II and III electropositive metal atoms lose a specific number of electrons and have a steady positive oxidation number.