19
K
Alkali metal

Potassium

Atomic number 19 · Period 4 · Block S

K · Potassium
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Understanding the element

Potassium (K) is chemical element 19. It belongs to the alkali metals, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.

Where do we encounter it?

In practice, it turns up most often in fertiliser production, biology and soaps and chemical bases.

fertiliser productionbiologysoaps and chemical bases
Standard atomic weight39.0983(1)

What its position in the table tells us

Potassium sits in period 4, group 1 and the S block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.

Worth remembering
Potassium has a characteristic place in the periodic table that helps explain both its chemistry and its practical uses

Scientific sources

Element identity
Atomic number19
Group1
Period4
BlockS
CategoryAlkali metal
PhaseSolid