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Why do alkali metals such as potassium readily form positive ions?
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![A periodic table element box for potassium shows atomic number 19, symbol K, atomic weight 39.0983, electron configuration [Ar]4s1, and name potassium. Icons indicate it is an alkali metal, solid at room temperature, body-centered cubic crystal structure, and has strongly basic higher-valence oxides. A key explains the symbols for alkali metals, solid state, body-centered cubic structure, and strong basicity.](https://cdn.britannica.com/81/22381-050-E3372C94/properties-Potassium.jpg)
potassium
Properties of potassium.
Alkali metals, including potassium, readily form positive ions because each atom has a single valence electron in its outermost shell. This electron is held much more weakly than those in inner shells, making it relatively easy to remove.12
The energy required to remove this outermost electron is known as the ionization energy. Because alkali metals have low ionization energies, they tend to lose this single electron during chemical reactions with nonmetals to achieve a more stable configuration, resulting in the formation of singly charged positive ions, or cations. In the case of potassium, it easily loses its single 4s electron to typically adopt a +1 oxidation state.132