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34 - Selenium polyatomic nonmetal

Discovered by Jöns Berzelius in 1817

Selenium

Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between those of its periodic table column-adjacent chalcogen elements sulfur and tellurium. It rarely occurs in its elemental state in nature, or as pure ore compounds.

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
57-71 La-Lu Lanthanides
89-103 Ac-Lr Actinides
Shell Electrons Orbitals
1 2 2 in 1s
2 8 2 in 2s + 6 in 2p
3 18 2 in 3s + 6 in 3p + 10 in 3d
4 6 2 in 4s + 4 in 4p
SeleniumSe Electron 1 Electron 2 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 9 Electron 10 Electron 11 Electron 12 Electron 13 Electron 14 Electron 15 Electron 16 Electron 17 Electron 18 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6
79  u Atomic Mass
1.2  Å Atomic Radius
958  K Boiling Point
1.2  Å Covalent Radius
4.81  g/cm³ Density
195 Electron Affinity
2.55 Electronegativity
9.75  eV First Ionization Energy
494  K Melting Point
4 Number of Shells
6 Electron Valency
34 Atomic Number
2, 8, 18, 6 Electron Shell Occupations
0.321  J/(g K) Specific Heat