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Element 33 - Arsenic (As)
From
arsenikos
, or male (the Greeks believed that metals differed in sex); discovered about 1250. Best classed as a metalloid with a few metallic traits arsenic is famed as a poison but some of its compounds are medicines. When heated, it "sublimes"--the solid vaporizes directly.
Properties
Atomic Number
:
33
Atomic Weight
:
74.9216
Electron Configuration
(at ground state):
1s
2
2s
2
2p
6
3s
2
3p
6
3d
10
4s
2
4p
3
Oxidation States
(Bold most stable):
-3
, +3, +5
Boiling Point
(K):
876 (sublimes)
Melting Point (K):
1090 (28 atm)
Density
(at 300K -- g/cm
3
):
5.78
Atomic Volume (at 300K -- cm
3
/mol)
13.10
Number of stable
isotopes
:
1
Mass Number
(Bold naturally occurring) --
Half-Life
--
Disintigration Type
:
73 -- 80.3 days -- orbital
electron capture
74 -- 17.9 days --
beta particle
(
electron
) emission,
positron
emission, orbital
electron capture
Covalent Radius (Å):
1.20
Atomic Radius (Å):
1.39
First
Ionization Potential
(V):
9.81
Electronegativity
(Pauling's):
2.18
Specific Heat
Capacity (at 300K -- J g
-1
K
-1
):
0.33
Heat of Vaporization (kJ/mol):
32.4
Heat of Fusion (kJ/mol):
27.7
Electrical Conductivity (at 293K for polycrystalline material -- 10
6
-1
cm
-1
):
3.8
Thermal Conductivity (at 300K -- W m
-1
K
-1
):
50
Crystal Structure:
Rhombohedral
Acid
-
Base
Properties:
Slightly acidic