Potassium

Alkali metal · atomic number 19

1939.09831KPotassiumSolidAlkali metal

Potassium is a chemical element with symbol K (derived from Neo-Latin, kalium) and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name is derived. In the Periodic table, potassium is one of seven elements in column (group) 1 (alkali metals):they all have a single valence electron in their outer electron shell, which they readily give up to create an atom with a positive charge - a cation, and combine with anions to form salts.

Properties of Potassium

Element category	Alkali metal
Atomic number	19
Atomic mass	39.09831 u
Phase at STP	Solid
Group	1
Period	4
Block	s
Electron configuration	[Ar] 4s1
Electrons per shell	2, 8, 8, 1
Electronegativity (Pauling)	0.82
Melting point	336.7 K (64 °C)
Boiling point	1032 K (759 °C)
Density	0.862 g/cm3
Discovered by	Humphry Davy

← Argon · Periodic table · Calcium → Ca

About the alkali metal group

Soft, wildly reactive metals of group 1 — they fizz in water and never occur pure in nature. Lithium, sodium, potassium and friends.

Data: Periodic-Table-JSON (CC BY-SA 3.0) · stored statically on our server. https://en.wikipedia.org/wiki/Potassium

Explore by category — Periodic Table /unsur

⚛️ Full periodic table

All 118 chemical elements on one interactive, colour-coded table, each linking to a fact file and plain-language summary.

🧪 Reactive nonmetal

11 elements: Elements that readily gain or share electrons — the building blocks of water, air, living tissue and most organic chemistry.

🧪 Noble gas

6 elements: Full outer electron shells make these gases almost inert: they barely react, glow in discharge lamps and are used to create unreactive atmospheres.

🧪 Alkali metal

6 elements: Soft, wildly reactive metals of group 1 — they fizz in water and never occur pure in nature. Lithium, sodium, potassium and friends.

🧪 Alkaline earth metal

6 elements: Reactive group-2 metals a step calmer than the alkalis: magnesium, calcium and the structural and biological workhorses among them.

🧪 Transition metal

35 elements: The dense, strong, catalytic heart of the table — iron, copper, gold, titanium — responsible for most of metallurgy, jewellery and industry.

🧪 Post-transition metal

9 elements: Softer, lower-melting metals beside the transition block — aluminium, tin, lead — abundant in cans, foils, solders and pigments.

🧪 Metalloid

7 elements: In-between elements that behave as semiconductors: silicon, germanium and boron underpin electronics, glass and solar cells.

🧪 Lanthanide

15 elements: The rare-earth “inner transition” metals that give strong permanent magnets, screen phosphors and catalyst polish.

🧪 Actinide

15 elements: Mostly radioactive, heavy metals — several made only in reactors — whose fission powers nuclear energy and weapons.

🧪 Unknown properties

8 elements: Superheavy synthetic elements made atom-by-atom, existing for fractions of a second; their true chemistry is still unmeasured.