Mendeleev's Periodic Table > K - Potassium

K - Potassium

In 1807, Humphrey Davy electrolyzed "fused potash" (KOH) to form pure potassium at the cathode. Potassium, also known as kalium, is a soft alkali metal and one of the most active metals known. Potassium is never found free in nature, but is obtained by electrolysis of the chloride or hydroxide, much in the same manner as prepared by Davy. It is one of the most reactive and electropositive of metals and, apart from lithium, it is the least dense known metal. It is soft and easily cut with a knife. Potassium is silvery in appearance immediately after a fresh surface is exposed. It oxidises very rapidly in air and must be stored under argon or under a suitable mineral oil. As do all the other metals of the alkali group, it decomposes in water with the evolution of hydrogen. It usually catches fire during the reaction with water.

Atomic number	-	19		Density	g/mL	0	.86
Atomic weight	u	39	.0983	Melting point	K	336	.35
Bonding radius	A	2	.03	Boiling point	K	1032
Atomic radius	A	2	.77	Heat of vaporization	kJ/mol	79	.87
Ionization Potential	V	4	.341	Heat of fusion	kJ/mol	2	.334
Electronegativity	-	0	.82	Specific heat	J/gK	0	.75
The oxide is a strong base.				Crystal are body centered cubic.
Electron config. : [Ar] 4s¹

Isotopes of K (Potassium):

MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	035 190 msec EC/ECp,11.881 Ar-35/Cl-34 34.988011	036 342 msec EC/ECa/ECp,12.805 Ar-36/S-32/Cl-35 35.981293	037 1.226 sec EC,6.149 MeV Ar-37 36.973376	038 7.636 min EC,5.913 MeV Ar-38 37.969080
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	038a 923.9 msec EC,6.043 MeV Ar-38 37.969219	039 93.2581% Stable 38.963706	040 0.0117% 1.277E+9 yr B-/EC,1.311 Ca-40/Ar-40 39.963998	041 6.7302% Stable 40.961825
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	042 12.360 hr B-,3.525 MeV Ca-42 41.962403	043 22.3 hr B-,1.815 MeV Ca-43 42.960715	044 22.13 min B-,5.660 MeV Ca-44 43.961556	045 17.3 min B-,4.204 MeV Ca-45 44.960699
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	046 105 sec B-,7.716 MeV Ca-46 45.961976	047 17.50 sec B-,6.643 MeV Ca-47 46.961677	048 6.8 sec B-/B-n,12.090 Ca-48/Ca-47 47.965512	049 1.26 sec B-/B-n,10.970 Ca-49/Ca-48 48.967450
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	050 472 msec B-/B-n,14.200 Ca-50/Ca-49 49.972731	051 365 msec B-/B-n,3.560 Ca-51/Ca-50 50.975833	052 105 msec B-/B-n,8.020 Ca-52/Ca-51 51.982261	053 30 msec B-/B-n,10.280 Ca-53/Ca-52 52.986732
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	054 10 msec B-/B-n,18.000 Ca-54/Ca-53 53.993988