Symbol	K
Atomnummer	19
Gruppe	1 (Alkalimetaller)
Periode	4
Blok	s
Klassifikation	Alkalimetaller

Udseende	Silvery gray
Farve	Sølv

Antal protoner	19 p+
Antal neutroner	20 n0
Antal elektroner	19 e-

Fra Wikipedia, den gratis encyklopædiKalium (kemisk symbol K, nummer 19 i det periodiske system, atommasse 39,102, naturlig forekomst ca 2,59%) er et såkaldt alkalimetal (alkalisk betyder basisk, dvs syreneutraliserende eller elektronafgivende). Alkalimetaller er medlemmer af den første hovedgruppe i det periodiske system. Ordet kalium stammer fra arab. al-qali, "planteaske". Det engelske navn, potassium, kommer af "potash" (potaske). Kemisk set udviser kalium og alle andre alkalimetaller stor reaktionskraft, hvilket skyldes, at de kun indeholder én uparret elektron i den yderste skal. Kalium overgår således også natrium.

Fase ved STP	Fast
Massefylde	0.862 g/cm3
Atommasse	39.0983 u

Smeltepunkt	336.7 K 63.55 °C 146.39 °F
Kogepunkt	1032 K 758.85 °C 1397.93 °F
Fordampningsvarme	76.9 kJ/mol

Elektronegativitet (Pauling Scale)	0.82
Elektronaffinitet	48.383 kJ/mol
Oxidationstrin	−1, +1 (a strongly basic oxide)
Ioniseringsenergier	418.8 kJ/mol 3052 kJ/mol 4420 kJ/mol 5877 kJ/mol 7975 kJ/mol 9590 kJ/mol 11343 kJ/mol 14944 kJ/mol 16963.7 kJ/mol 48610 kJ/mol 54490 kJ/mol 60730 kJ/mol 68950 kJ/mol 75900 kJ/mol 83080 kJ/mol 93400 kJ/mol 99710 kJ/mol 444880 kJ/mol 476063 kJ/mol

Elektronkonfiguration Kortfattet konfiguration	[Ar] 4s1
Elektronkonfiguration Fuld konfiguration	1s2 2s2 2p6 3s2 3p6 4s1
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6 4s1
Elektroner pr. Skal	2, 8, 8, 1
Valenselektroner	1
Valency-elektroner	1
Bohrs atommodel	Figur: Skaldiagram af Kalium (K) atom.
Orbital diagram	1s 2s 2p 3s 3p 4s

Opdagelse og første isolation

Humphry Davy (1807)

Opdagelse af kalium The English name for the element potassium comes from the word potash, which refers to an early method of extracting various potassium salts: placing in a pot the ash of burnt wood or tree leaves, adding water, heating, and evaporating the solution. When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it potassium, which he derived from the word potash. The symbol K stems from kali, itself from the root word alkali, which in turn comes from Arabic: القَلْيَه al-qalyah 'plant ashes'. In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite, and realized that "potash" was not a product of plant growth but actually contained a new element, which he proposed calling kali. In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium". In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol K.

CAS Number	7440-09-7
ChemSpider ID	4575326
EC number	231-119-8
PubChem CID Number	5462222