| From Wikipedia, the free encyclopediaHydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 1.00794 u, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass. | |||
Hydrogen in the periodic table | |||
|---|---|---|---|
| Symbol | H | ||
| Atomic number | 1 | ||
| Group | 1 | ||
| Period | 1 | ||
| Block | s | ||
| Element category | Nonmetal | ||
Physical properties | |||
| Phase at STP | Gas | ||
| Density | 0.08988 g/cm3 | ||
| Atomic weight | 1.0079 u | ||
| Melting point | 13.99 K -259.16 °C -434.488 °F | ||
| Boiling point | 20.271 K -252.879 °C -423.1822 °F | ||
Atomic properties | |||
| Electronegativity (Pauling Scale) | 2.2 | ||
| Electron affinity | 72.769 kJ/mol | ||
| Oxidation states | −1, +1 (an amphoteric oxide) | ||
| Ionization energies |
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Electron configuration | |||
| Elektronkonfiguration (shorthand) | 1s1 | ||
| Electron configuration | 1s1 | ||
| Electrons per shell | 1 | ||
History | |||
| Discovered | 1766 | ||
| Discovered by | Henry Cavendish | ||
| Named by | Antoine Lavoisier | ||