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| General
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| Name, Symbol, Number
| selenium, Se, 34
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| Series
| nonmetals
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| Group, Period, Block
| 16 (VIA), 4 , pThe p-block of the periodic table of elements consists of the last six groups. In the elemental form of the p-block elements, the highest energy electron occupies a p- orbital. The p-block contains all of the nonmetals and semimetals, as well as some of t
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| DensityFor other meanings of density, see density (disambiguation Density (symbol: rho Greek: rho) is a measure of mass per unit of volume. The higher an object's density, the higher its mass per volume. The average density of an object equals its total mass div, Hardness
| 4790 kg/m3Kilogram per cubic metre is the SI measure of density and is represented as kg/m³, where kg stands for kilogram and m³ stands for cubic metre. The density of water is about 1000 kg/m³, since a cubic metre of water weighs about a tonne. kg/m³" is sometimes(300 KThe kelvin (symbol: K is the SI unit of temperature, and is one of the seven SI base units. It is defined by two facts: zero kelvin is absolute zero (when molecular motion stops), and one kelvin is the fraction 1/273. 16 of the thermodynamic temperature o), 2
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| AppearanceFor alternative meanings, see color (disambiguation). visual arts. Color (or colour is a sensation which (in humans) derives from the ability of the fine structure of the eye to distinguish three differently filtered analyses of a view. The perception of
| grey, metallic lustre
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| Atomic properties
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| Atomic weightIn reference to a certain isotope of a chemical element, atomic weight (more accurately relative atomic mass though also called simply atomic mass is the mass of one atom of the isotope expressed in units atomic mass unit amu) such that the Carbon-12 isot
| 78.96 amuThe atomic mass unit amu , unified atomic mass unit u , or dalton Da , is a small unit of mass used to express atomic masses and molecular masses. It is defined to be 1/12 of the mass of one atom of Carbon-12. Accordingly, :1 u 1/N gram 1/(1000 N) kg (whe
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| Atomic radius (calc.)
| 115 (103) pm
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| Covalent radius
| 116 pm
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| van der Waals radius
| 190 pm
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| Electron configuration
| [ Ar]3d104p44s2
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| e- 's per energy level
| 2, 8, 18, 6
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| Oxidation states ( Oxide)
| ±2,4,6 (strong acid)
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| Crystal structure
| hexagonal
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| Physical properties
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| State of matter
| solid ( __)
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| Melting point
| 494 K (430 ° F)
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| Boiling point
| 957.8 K (1265 °F)
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| Molar volume
| 16.42 ×10-6 m3/mol
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| Heat of vaporization
| 26.3 kJ/mol
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| Heat of fusion
| 6.694 kJ/mol
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| Vapor pressure
| 0.695 Pa at 494 K
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| Speed of sound
| 3350 m/s at 293.15 K
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| Miscellaneous
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| Electronegativity
| 2.48 ( Pauling scale)
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| Specific heat capacity
| 320 J/(kg*K)
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| Electrical conductivity
| 1.0E-10 106/(m· ohm)
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| Thermal conductivity
| 2.04 W/(m*K)
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| 1st ionization potential
| 941 kJ/mol
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| 2nd ionization potential
| 2045 kJ/mol
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| 3rd ionization potential
| 2973.7 kJ/mol
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| 4th ionization potential
| 4144 kJ/mol
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| Most stable isotopes
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| iso
| NA
| half-life
| DM
| DE M eV
| DP
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| 72Se
| {syn.}
| 8.4 d
| Ε
| 0.335
| 72As
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| 74Se
| 0.87%
| Se is stable with 40 neutrons
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| 75Se
| {syn.}
| 119.779 d
| Ε
| 0.864
| 75As
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| 76Se
| 9.36%
| Se is stable with 42 neutrons
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| 77Se
| 7.63%
| Se is stable with 43 neutrons
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| 78Se
| 23.78%
| Se is stable with 44 neutrons
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| 79Se
| {syn.}
| 1.13 E6 y
| β
| 0.151
| 79Br
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| 80Se
| 49.61%
| Se is stable with 46 neutrons
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| 82Se
| 8.73%
| 1.08 E20 y
| β
| 2.995
| 82Kr
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| SI units & STP are used except where noted.
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