Atomic Properties
- Atomic Number
- 19
- Atomic Mass
- 39.0980 u
- Electron Configuration
- [Ar] 4s1
- Electronegativity
- 0.82
- Block
- s-block
- Group
- 1
- Period
- 4
Physical Properties
- Phase (STP)
- solid
- Melting Point
- 336.70 K
- Boiling Point
- 1032.00 K
- Density
- 0.8900 g/cm³
About Potassium
Essential nutrient; reacts violently with water; used in fertilizers.
Why "K" for Potassium?
K←Kalium(Latin)
The symbol K comes from "Kalium," the Latin name derived from Arabic "qali" meaning "alkali" (plant ashes). The English name "Potassium" comes from "potash," the ash residue left in pots after burning plant material.
Isotopes of Potassium
Potassium has 3 naturally occurring isotopes.
| Isotope | Mass Number | Atomic Mass (u) | Abundance | Type |
|---|---|---|---|---|
| 39K | 39 | 38.96370649 | 93.26% | Stable |
| 40K | 40 | 39.96399817 | 0.0117% | Stable |
| 41K | 41 | 40.96182526 | 6.730% | Stable |
Data source: NIH PubChem (aggregated from IUPAC, NIST)