Hydrogen (H) – element 1
Hydrogen is a chemical element with the symbol H and atomic number 1. It is a reactive nonmetal in group 1, period 1 of the periodic table (s-block), and is a gas at room temperature.
Hydrogen (H) has atomic number 1, atomic mass 1.008 u and electron configuration 1s1.
Hydrogen facts
| Symbol | H |
|---|---|
| Atomic number | 1 |
| Atomic mass | 1.008 u (g/mol) |
| Category | reactive nonmetal |
| Group | group 1 |
| Period | 1 |
| Block | s-block |
| Phase at 20 °C | Gas |
| Electron configuration | 1s1 |
| Noble-gas notation | 1s1 |
| Electrons per shell | 1 |
| Valence electrons | 1 |
Bohr model and shells
Hydrogen has 1 electrons in 1 shell: 1. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 13.99 K (-259.2 °C) |
|---|---|
| Boiling point | 20.271 K (-252.9 °C) |
| Density | 0.08988 g/L |
| Electronegativity (Pauling) | 2.2 |
| Electron affinity | 72.769 kJ/mol |
| Ionization energies | 1312 kJ/mol (1st) |
| Molar heat capacity | 28.836 J/(mol·K) |
| Discovered by | Henry Cavendish |
Use the atomic mass in the molar mass calculator for any formula containing H.
Position in the periodic table
Tap any element to open its page.
Molecules with hydrogen
Rotate each one in 3D, or draw your own structure in MolDraw.
Frequently asked questions
What is the atomic mass of hydrogen?
The atomic mass of hydrogen is 1.008 u, so one mole of hydrogen atoms weighs 1.008 g.
What is the electron configuration of hydrogen?
Hydrogen has 1 electrons: 1s¹, or 1s¹ in noble-gas notation. Electrons per shell: 1.
How many valence electrons does hydrogen have?
Hydrogen has 1 valence electron (group 1).
Is hydrogen a metal?
No. Hydrogen is a nonmetal (reactive nonmetal).
Where is hydrogen on the periodic table?
Hydrogen is in group 1, period 1, in the s-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.