Hydrogen (H)
Hydrogen (H) is element 1 of the periodic table, a nonmetal in period 1 and group 1. Its standard atomic weight is 1.008, so one mole of hydrogen atoms has a mass of 1.008 g. At room temperature it is a gas; it melts at -259.34 °C and boils at -252.87 °C.
| Atomic number | 1 |
|---|---|
| Symbol | H |
| Standard atomic weight | 1.008 |
| Molar mass | 1.008 g/mol |
| Category | Nonmetal |
| Group | 1 |
| Period | 1 |
| Block | s-block |
| Electron configuration | 1s1 |
| Oxidation states | +1, −1 |
| Electronegativity (Pauling) | 2.2 |
| Atomic radius (van der Waals) | 120 pm |
| First ionisation energy | 13.598 eV (1312 kJ/mol) |
| Electron affinity | 0.754 eV |
| State at room temperature | Gas |
| Melting point | 13.81 K (-259.34 °C) |
| Boiling point | 20.28 K (-252.87 °C) |
| Density | 0.0899 g/L |
| Discovered | 1766 |
Group 1
Calculate with Hydrogen
Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.