Atomic Properties of K
- Atomic Number of K
- 19
- Atomic Mass of K
- 39.0980 u
- Electron Configuration
- [Ar] 4s1
- Electronegativity
- 0.82
- Block
- s-block
- Group
- 1
- Period
- 4
Potassium metal is soft enough to cut, but its fresh surface cannot remain exposed for long. It reacts rapidly with air and far more vigorously with water, producing potassium hydroxide, hydrogen, and enough heat to ignite the hydrogen. Potassium compounds color a flame lilac, although the intense yellow emission from trace sodium can easily mask that signal.
Inside the body, potassium is not metal. It is K+, an essential ion concentrated mainly inside cells. The sodium-potassium pump uses cellular energy to maintain different sodium and potassium concentrations across membranes. When channels open, controlled ion movement changes voltage, allowing nerves to signal and muscles to contract. Heart rhythm depends on this balance, which is why both severe deficiency and excess potassium can be dangerous.
Bananas contain potassium, but they are only one source among potatoes, beans, leafy vegetables, dairy foods, and many others. Their fame should not obscure the broader nutritional chemistry. Natural potassium also includes a tiny fraction of radioactive potassium-40. Its extremely long half-life makes ordinary foods very slightly radioactive without making bananas hazardous. The isotope contributes to geological dating as well.
Plants require potassium, so mined potassium salts called potash are major fertilizers. Other compounds appear in glass, soap, fireworks, and explosives. The pure metal is produced under conditions that keep water away.
Potassium is a Spark Starter whose two identities must stay separate. The metal releases an electron with dramatic speed; living cells manage K+ with molecular gates and pumps. Reactivity becomes physiology only after chemistry changes the form and biology controls the flow.