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Pronunciation | |
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Allotropes | grey (most common), yellow, black (see Allotropes of arsenic) |
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Appearance | metallic grey |
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| 74.921595(6)[1] |
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Atomic number (Z) | 33 |
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Group | group 15 (pnictogens) |
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Period | period 4 |
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Block | p-block |
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Electron configuration | [Ar] 3d10 4s2 4p3 |
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Electrons per shell | 2, 8, 18, 5 |
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Phase at STP | solid |
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Sublimation point | 887 K (615 °C, 1137 °F) |
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Density (near r.t.) | 5.727 g/cm3 |
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when liquid (at m.p.) | 5.22 g/cm3 |
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Triple point | 1090 K, 3628 kPa[2] |
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Critical point | 1673 K, ? MPa |
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Heat of fusion | grey: 24.44 kJ/mol |
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Heat of vaporization | 34.76 kJ/mol (?) |
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Molar heat capacity | 24.64 J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
553 |
596 |
646 |
706 |
781 |
874 |
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Oxidation states | −3, −2, −1, 0,[3] +1,[4] +2, +3, +4, +5 (a mildly acidic oxide) |
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Electronegativity | Pauling scale: 2.18 |
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Ionization energies | - 1st: 947.0 kJ/mol
- 2nd: 1798 kJ/mol
- 3rd: 2735 kJ/mol
- (more)
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Atomic radius | empirical: 119 pm |
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Covalent radius | 119±4 pm |
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Van der Waals radius | 185 pm |
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Spectral lines of arsenic |
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Natural occurrence | primordial |
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Crystal structure | rhombohedral |
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Thermal expansion | 5.6 µm/(m⋅K)[5] (at r.t.) |
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Thermal conductivity | 50.2 W/(m⋅K) |
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Electrical resistivity | 333 nΩ⋅m (at 20 °C) |
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Magnetic ordering | diamagnetic[6] |
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Molar magnetic susceptibility | −5.5×10−6 cm3/mol[7] |
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Young's modulus | 8 GPa |
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Bulk modulus | 22 GPa |
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Mohs hardness | 3.5 |
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Brinell hardness | 1440 MPa |
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CAS Number | 7440-38-2 |
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Discovery | Arabic alchemists (before AD 815) |
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Main isotopes[8] |
Decay |
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abundance |
half-life (t1/2) |
mode |
product |
73As |
synth |
80.3 d |
ε |
73Ge |
γ |
– |
74As |
synth |
17.8 d |
ε |
74Ge |
β+ |
74Ge |
γ |
– |
β− |
74Se |
75As |
100% |
stable |
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Category: Arsenic | references |