- potassium - Properties, occurrence, and uses
- potassium - Principal compounds and reactions with other elements
- chemical compound - Trends in the chemical properties of the elements
- alkaline-earth metal - Physical and chemical behaviour
- electronic configuration
- alkali metal - Physical properties
- alkali metal - Chemical properties
Why is potassium more reactive than sodium?
![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 is more reactive than sodium primarily because of the difference in their ionization energy, which is the energy required to remove an electron from an atom.1
As you move down the alkali metals group in the periodic table, the atoms become larger and the valence electron is located increasingly farther from the positive nucleus. Because this electron is further away, it is less strongly attracted to the nucleus and therefore easier to remove.12
Specifically, potassium has a lower first ionization energy (418.8 kJ/mol) compared to sodium (495.8 kJ/mol). This lower energy requirement allows potassium to lose its valence electron more readily, making it more chemically reactive in its interactions with other substances, such as water and oxygen.231