Discovered By: Jons Jacob Berzelius
Discovery year: 1817

The following table showing some properties of Selenium(Se):

Table Example
Atomic number 34
Group 16
Period 4
Block p
Electrons 34
Protons 34
Neutrons 45
Atomic weight 78.971
Oxidation states -2, +2, +4, +6
Ionic charge Se^2-


Table Example
Electrons per shell K2 L8 M18 N6
Electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^4
Atomic radius 103 pm
Covalent radius 120 pm
Van der Waals radius 190 pm
Boiling point 685°C
Melting point 221°C
Phase Solid
Fusion heat 5.4 kJ.mol^-1
Vaporization heat 26 kJ.mol^-1


Table Example
Colot Gray
Brinell hardness 736 MPa
Bulk modulus 8.3 GPa
Density 4819 kg.m^-3
Liquid density 3990 kg.m^-3
Mohs hardness 2
Molar volume 1.639*10^-5 m^3.mol^-1
Refractive index 1.000895
Poisson ratio 0.33
Shear modulus 3.7 GPa


Table Example
Sound speed 3350 m.s^-1
Young's modulus 10 GPa
Magnetic type Diamagnetic
Volume magnetic susceptibility -1.93*10^-5
Electronegativity 2.55
Valence 6
Electron affinity 195 kJ.mol^-1
First ionization energy 941 kJ.mol^-1
Radioactive No
neutron cros section 11.7 barn