Symbol	K
Atomic number	19
Group	1 (Alkali metal)
Period	4
Block	s
Classification	Alkali Metal

Appearance	Silvery gray
Color	Silver

Number of protons	19 p+
Number of neutrons	20 n0
Number of electrons	19 e-

From Wikipedia, the free encyclopediaPotassium 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.

Phase at STP	Solid
Density	0.862 g/cm3
Atomic weight	39.0983 u

Melting point	336.7 K 63.55 °C 146.39 °F
Boiling point	1032 K 758.85 °C 1397.93 °F
Heat of vaporization	76.9 kJ/mol

Electronegativity (Pauling Scale)	0.82
Electron affinity	48.383 kJ/mol
Oxidation states	−1, +1 (a strongly basic oxide)
Ionization energies	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

Electron configuration Shorthand configuration	[Ar] 4s1
Electron configuration Full configuration	1s2 2s2 2p6 3s2 3p6 4s1
Electron configuration chart	1s2 2s2 2p6 3s2 3p6 4s1
Electrons per shell	2, 8, 8, 1
Valence electrons	1
Valency electrons	1
Bohr model	Figure: Shell diagram of Potassium (K) atom.
Orbital Diagram	1s 2s 2p 3s 3p 4s

Discovery and first isolation

Humphry Davy (1807)

Discovery of potassium 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