Hydrogen
Hydrogen is a chemical element with the symbol H and atomic number 1. It has a standard atomic weight of 1.008, sits in period 1 and group 1, and is classified as a reactive nonmetal.
Properties
| Symbol | H |
|---|---|
| Atomic number | 1 |
| Standard atomic weight | 1.008 |
| Category | Reactive nonmetal |
| Group | 1 |
| Period | 1 |
| Electron configuration | 1s1 |
| Outer-shell electrons | 1 |
The figure of 1.008 is a conventional value, because IUPAC publishes an interval for this element rather than a single weight. For elements like this one the fourth digit carries real uncertainty, because the isotopic composition varies measurably between natural sources — so quoting eight digits would overstate what is known.
Compounds containing hydrogen
396 of the compounds in this reference contain H, listed by the fraction of their mass it makes up.
| Compound | Formula | Atoms | % by mass |
|---|---|---|---|
| hydrogen | H2 | 2 | 100.0% |
| methane | CH4 | 4 | 25.1% |
| propane | C3H8 | 8 | 18.3% |
| ammonia | H3N | 3 | 17.8% |
| butane | C4H10 | 10 | 17.3% |
| pentane | C5H12 | 12 | 16.8% |
| hexane | C6H14 | 14 | 16.4% |
| heptane | C7H16 | 16 | 16.1% |
| octane | C8H18 | 18 | 15.9% |
| decane | C10H22 | 22 | 15.6% |
| dodecane | C12H26 | 26 | 15.4% |
| diethylamine | C4H11N | 11 | 15.2% |
| triethylamine | C6H15N | 15 | 14.9% |
| ammonium hydroxide | H5NO | 5 | 14.4% |
| cycloheptane | C7H14 | 14 | 14.4% |
| cyclopentane | C5H10 | 10 | 14.4% |
| methylcyclohexane | C7H14 | 14 | 14.4% |
| cyclohexane | C6H12 | 12 | 14.4% |
| ethylene | C2H4 | 4 | 14.4% |
| propylene | C3H6 | 6 | 14.4% |
| pentanol | C5H12O | 12 | 13.7% |
| putrescine | C4H12N2 | 12 | 13.7% |
| butanol | C4H10O | 10 | 13.6% |
| diethyl ether | C4H10O | 10 | 13.6% |
| tert-butanol | C4H10O | 10 | 13.6% |
Showing the 25 with the highest H content, of 396.
Calculate with hydrogen
- Molar mass of any formula containing it
- Electron configuration, including ions
- Effective nuclear charge by Slater's rules
- Average atomic mass from isotope abundances
Group 1
Atomic weights are the IUPAC 2021 standard values, abridged to the conventional five significant figures. Group, period, category and electron configuration are derived from the atomic number rather than stored, so they cannot drift out of step with it.