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Element 19 - Potassium (K)
From potash, an impure form of potassium carbonate known to the ancients; symbol K from its Latin name
kalium
, discovered 1807. Seventh most abundant element in the earth's crust. Its radioactivity, though mild, may be one natural cause of genetic mutation in man.
Properties
Atomic Number
:
19
Atomic Weight
:
39.0983
Electron Configuration
(at ground state):
1s
2
2s
2
2p
6
3s
2
3p
6
4s
1
Oxidation States
(Bold most stable):
+1
Boiling Point
(K):
1033
Melting Point (K):
336.8
Density
(at 300K -- g/cm
3
):
0.86
Atomic Volume (at 300K -- cm
3
/mol)
45.30
Number of stable
isotopes
:
2
Number of natural
radioactive
isotopes:
1
Mass Number
(Bold naturally occurring) --
Half-Life
--
Disintigration Type
:
40
-- 1.28 x 10
9
years -- orbital
electron capture
42 -- 12.36 hours --
beta particle
(
electron
) emission
Covalent Radius (Å):
2.03
Atomic Radius (Å):
2.35
First
Ionization Potential
(V):
4.341
Electronegativity
(Pauling's):
0.82
Specific Heat
Capacity (at 300K -- J g
-1
K
-1
):
0.757
Heat of Vaporization (kJ/mol):
76.9
Heat of Fusion (kJ/mol):
2.33
Electrical Conductivity (at 293K for polycrystalline material -- 10
6
-1
cm
-1
):
16.4
Thermal Conductivity (at 300K -- W m
-1
K
-1
):
102.5
Crystal Structure:
Cubic, body centered
Acid
-
Base
Properties:
Very basic