## Cesium |

Symbol | Cs |
---|---|

Latin name | Caesium |

Atomic number | 55 |

Period | 6 |

Element category | Alkali metals |

Relative atomic mass | 132.90543 |

Group | I.A |

Electronegativity | 0.7 |

Oxidation numbers | 1 |

Electron configuration | 1s ^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{6} 4d^{10} 5s^{2} 5p^{6} 6s^{1} |

Density [g/cm^{3}] | 1.873 |

State | Solid |

Melting point [°C] | 28.40 |

Boiling point [°C] | 700 |

Critical point [°C] | 1665 |

Critical pressure [MPa] | 9.4 |

Atomic radius [pm] | 298 |

Covalent radius [pm] | 225 |

Thermal conductivity [W m^{-1}K^{-1}] | 35.9 |

Heat capacity [J K^{-1}g^{-1}] | 0.24 |

Discovery | 1860 |

Hardness [Mohs scale] | 0.2 |

Young's modulus [GPa] | 1.7 |

Electrical conductivity [S m^{-1}] | 5.3 · 10 ^{6} |

1.st ionization energy [eV] | 3.8939 |

2.nd ionization energy [eV] | 25.10 |

Stable isotopes | 2 |

Unstable isotopes | 19 |