## Selenium |

Symbol | Se |
---|---|

Latin name | Selenium |

Atomic number | 34 |

Period | 4 |

Element category | Nonmetals |

Relative atomic mass | 78.96 |

Group | VI.A |

Electronegativity | 2.4 |

Oxidation numbers | -2, 2, 4, 6 |

Electron configuration | 1s ^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{4} |

Density [g/cm^{3}] | 4.80 |

State | Solid |

Melting point [°C] | 217 |

Boiling point [°C] | 685 |

Critical point [°C] | 1493 |

Critical pressure [MPa] | 27.2 |

Thermal conductivity [W m^{-1}K^{-1}] | 2.04 |

Heat capacity [J K^{-1}g^{-1}] | 0.32 |

Discovery | 1817 |

Hardness [Mohs scale] | 2.0 |

Brinell hardness [MPa] | 736 |

Young's modulus [GPa] | 10 |

Electrical conductivity [S m^{-1}] | 8 · 10 ^{6} |

Shear modulus [GPa] | 3.7 |

1.st ionization energy [eV] | 9.7524 |

2.nd ionization energy [eV] | 21.19 |

3.rd ionization energy [eV] | 30.82 |

Stable isotopes | 6 |

Unstable isotopes | 14 |