Here's why:

* Group 1 Element: Potassium belongs to Group 1 of the periodic table, which are known as alkali metals.

* Tendency to Lose Electrons: Alkali metals have a strong tendency to lose one electron to achieve a stable electron configuration like the noble gases.

* Cation Formation: When potassium loses one electron, it forms a +1 cation (K+).

Exceptions:

While +1 is the most common oxidation state for potassium, there are some rare cases where it can have different oxidation numbers, especially in certain complex compounds. However, these are not typical and are beyond the scope of general chemistry.