potassium - Isotopes, Potassium in nutrition and medicine

K (Lat kalium), element 19, melting point 63°C. One of the most reactive metals, and the third of the alkali metal group. It is not found free in nature, but obtained chiefly from mineral deposits of the chloride (KCl) and the nitrate (KNO₃, also known as nitre or saltpetre). The metal is prepared by the electrolysis of molten KCl or KOH. It is an important strong reducing agent, and must be kept away from water, with which it reacts explosively. In virtually all of its compounds, it has oxidation state +1. These are important mainly as agricultural chemicals and explosives.

19 argon ← potassium → calcium Na ↑ K ↓ Rb Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	potassium, K, 19
Chemical series	alkali metals
Group, Period, Block	1, 4, s
Appearance	brownish white
Atomic mass	39.0983(1) g/mol
Electron configuration	[Ar] 4s1
Electrons per shell	2, 8, 8, 1
Physical properties
Phase	solid
Density (near r.t.)	0.89 g·cm−3
Liquid density at m.p.	0.828 g·cm−3
Melting point	336.53 K (63.38 °C, 146.08 °F)
Boiling point	1032 K (759 °C, 1398 °F)
Critical point	( K, {{{mpa}}} MPa
Crystal structure	cubic body centered
Oxidation states	1 (strongly basic oxide)
Electronegativity	0.82 (Pauling scale)
Ionization energies (more)	1st: 418.8 kJ·mol−1
	2nd: 3052 kJ·mol−1
	3rd: 4420 kJ·mol−1
Atomic radius	220 pm
Atomic radius (calc.)	243 pm
Covalent radius	196 pm
Van der Waals radius	275 pm
Miscellaneous
Magnetic ordering	?
Thermal conductivity	(300 K) 102.5 W·m
Thermal expansion	(25 °C) 83.3 µm·m
Speed of sound (thin rod)	(20 °C) 2000 m/s
Shear modulus	1.3 GPa
Bulk modulus	3.1 GPa
Mohs hardness	0.4
Brinell hardness	0.363 MPa
CAS registry number	7440-09-7
Selected isotopes
Main article: Isotopes of potassium iso NA half-life DM DE (MeV) DP 39K 93.26% K is stable with 20 neutrons 40K 0.012% 1.277×109 y β- 1.311 40Ca ε 1.505 40Ar β+ 1.505 40Ar 41K 6.73% K is stable with 22 neutrons
References

Potassium (IPA: /pə(ʊ)ˈtasiəm/) is a chemical element. In animal cells potassium ions are vital to keeping cells alive (see Na-K pump) Potassium chloride is used as a substitute for table salt and is also used to stop the heart, e.g.

Many potassium salts are very important, and include: potassium bromide, potassium carbonate, potassium chlorate, potassium chloride, potassium chromate, potassium cyanide, potassium dichromate, potassium iodide, potassium nitrate, potassium sulfate.

See also potassium minerals.

Isotopes

There are seventeen known isotopes of potassium.

Potassium in nutrition and medicine

Potassium is an essential mineral micronutrient in human nutrition;

Supplements of potassium in medicine are most widely used in conjunction with the most powerful classes of diuretics, which rid the body of sodium and water, but have the side effect of also causing potassium loss in urine. End stage renal failure patients undergoing therapy by renal dialysis must observe strict dietary limits on potassium intake, since the kidneys control potassium excretion, and buildup of blood concentrations of potassium may trigger fatal heart dysrhythmias.