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Potassium, K

Potassium is a chemical element. It has the symbol K (Arabic: al qalja‎ → Latin: kalium) and atomic number 19. The name "potassium" comes from the word "potash", as potassium was first isolated from potash. Potassium is a soft silvery-white metallic alkali metal that occurs naturally bound to other elements in seawater and many minerals. It oxidizes rapidly in air and is very reactive, especially towards water. In many respects, potassium and sodium are chemically similar, although organisms in general, and animal cells in particular, treat them very differently.

Evaporation Materials

Technical Data
Symbol	K	Melting point /°C	63.2
Atomic number	19	Boiling point /°C	765.5
No. of naturally occurring isotopes	2+1*	ΔH_fus/kJmol^-1	2.39
Atomic weight	39.0983	ΔH_vap/kJmol^-1	79
Electronic configuration	[Ar]4s¹	ΔH_{f(monoatomic gas)}/kJmol^-1	90
Metal radius/pm	227	ΔH_(dissoc)/kJmol^-1	49.9
Ionic radius(6-coordinate)/pm	138	Ionization energy/kJmol^-1	418.6
E^o(M⁺_(aq)+e^-→M_(S))/V	-2.925	*(radioactive ⁴°K t_1/2 1.27 x 10⁹ y)
Density (20°C)/gcm³	0.856

Evaporation Techniques
Temperature (^oC) @Vap. Pressure			Techniques				Remarks
10^-8 Torr	10^-6 Torr	10^-4 Torr	Electron Beam	Crucible	Coil	Boat	Remarks
842	992	1192	Excellent	Al₂O₃	Tungsten	Tungsten	Alloys with refractory metals; rapid Evaporation suggested. Spits in EB.

Evaporation Materials
P4-5000-M small pieces

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