Potassium
Alkali Metal
Potassium (K) is a chemical element with atomic number 19, classified as a alkali metal. At room temperature it is a solid. It was discovered in 1807 by Humphry Davy.
Properties
- Atomic number
- 19
- Atomic mass
- 39.098 u
- Category
- Alkali Metal
- Group
- 1
- Period
- 4
- Block
- s-block
- Electron configuration
- [Ar] 4s¹
- Phase at STP
- Solid
- Density
- 0.862 g/cm³
- Melting point
- 336.53 K (63.4 °C)
- Boiling point
- 1032 K (758.9 °C)
- Electronegativity
- 0.82
- Atomic radius
- 243 pm
- Ionization energy
- 4.341 eV
- Discovery
- 1807 · Humphry Davy
Common uses
Fertilizers, soap, explosives, salt substitute
Did you know?
So reactive it must be stored under oil and explodes violently in water.
Compounds you can make with potassium
Potassium appears in 5 compounds in our periodic table sandbox. Each one is a real substance with its true chemical formula — combine the right elements in the right ratio below to discover it.
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KCl
Potassium Chloride
A salt substitute and essential nutrient, also used in fertilizers.
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KI
Potassium Iodide
Added to table salt to prevent iodine deficiency; also protects the thyroid.
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KOH
Potassium Hydroxide (Caustic Potash)
A powerful base used to make soft soaps, biodiesel, and alkaline batteries.
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KNO3
Potassium Nitrate (Saltpeter)
Saltpeter, an oxidizer in gunpowder, fertilizer, and food curing.
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KMnO4
Potassium Permanganate
An intensely purple oxidizer used to disinfect water and treat skin conditions.