11.008HHydrogen
Hydrogen (H) — element 1reactive nonmetal · group 1, period 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 (the s-block), with a standard atomic mass of 1.008 u. At room temperature (25 °C) hydrogen is a gas.
💡 Known for: The lightest and most abundant element in the universe — it fuels the stars and is part of every water molecule.
# Hydrogen properties
| Symbol | H |
|---|---|
| Atomic number | 1 |
| Atomic mass | 1.008 u |
| Category | reactive nonmetal |
| Group | 1 |
| Period | 1 |
| Block | s-block |
| Electron configuration | 1s¹ |
| Full configuration | 1s¹ |
| Electrons per shell | 1 |
| Protons / electrons | 1 / 1 |
| State at 25 °C | gas |
| Melting point | 14.01 K (-259.1 °C, -434.5 °F) |
| Boiling point | 20.28 K (-252.9 °C, -423.2 °F) |
| Density | 0.08988 g/L |
| Electronegativity (Pauling) | 2.2 |
| First ionization energy | 13.598 eV |
| Atomic radius | 53 pm |
| Discovered | 1766 |
# Electron configuration of hydrogen
The electron configuration of hydrogen is 1s¹. Its 1 electron fill 1 shell as 1, so the outermost shell holds 1 electron. As a group 1 element, hydrogen has 1 valence electron.
# Related elements
HeHeliumnext elementLiLithiumgroup 1NaSodiumgroup 1KPotassiumgroup 1RbRubidiumgroup 1CsCaesiumgroup 1FrFranciumgroup 1CCarbonreactive nonmetalNNitrogenreactive nonmetalOOxygenreactive nonmetalPPhosphorusreactive nonmetalSSulfurreactive nonmetalSeSeleniumreactive nonmetal
# Hydrogen FAQ
What is the atomic number of hydrogen?
The atomic number of hydrogen is 1: every hydrogen atom has 1 proton in its nucleus. Its symbol is H.
What is the atomic mass of hydrogen?
The standard atomic mass of hydrogen is 1.008 u.
What is the electron configuration of hydrogen?
Hydrogen's electron configuration is 1s¹, with 1 electrons per shell.
Is hydrogen a metal?
No. Hydrogen is a reactive nonmetal, a nonmetal.
What is the melting point of hydrogen?
Hydrogen melts at 14.01 K (-259.1 °C, -434.5 °F) and boils at 20.28 K (-252.9 °C, -423.2 °F).
What is hydrogen used for / known for?
The lightest and most abundant element in the universe — it fuels the stars and is part of every water molecule.