Hydrogen (H)
Hydrogen is element 1, a nonmetal in group 1, period 1. A neutral atom has 1 protons, 0 neutrons and 1 electrons, 1 of them valence electrons.
Nonmetal- Atomic number
- 1
- Atomic mass
- 1.008 u
- Valence electrons
- 1
- Protons · neutrons
- 1 · 0
- Electrons per shell
- 1
- At room temperature
- gas
Bohr model of hydrogen
The Bohr model draws hydrogen as a nucleus of 1 proton and 0 neutrons, with its 1 electron on 1 circular shell: 1 in shell 1. Press Build the atom to watch the shells fill from the inside out. The outer ring is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of hydrogen
1s¹
How many valence electrons does hydrogen have?
Hydrogen has 1 valence electron.
Hydrogen is in group 1, so it has 1 valence electron. It tends to lose that electron and form a +1 ion.
Protons, neutrons and electrons
| Protons | 1 | equal to the atomic number |
|---|---|---|
| Electrons | 1 | equal to the protons in a neutral atom |
| Neutrons | 0 | mass number 1 − 1 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Hydrogen properties
| Symbol | H |
|---|---|
| Category | Nonmetal |
| Group · period · block | 1 · 1 · s |
| Atomic mass | 1.008 u |
| State at 25 °C | gas |
| Melting point | 13.81 K (-259 °C, -435 °F) |
| Boiling point | 20.28 K (-253 °C, -423 °F) |
| Density | 8.99e-5 g/cm³ |
| Electronegativity (Pauling) | 2.2 |
| Atomic radius | 120 pm |
| First ionization energy | 13.598 eV |
| Electron affinity | 0.754 eV |
| Oxidation states | +1, −1 |
| Common ion charge | +1, −1 |
| Discovered | 1766 by Henry Cavendish |
Where hydrogen sits on the periodic table
Group 1: Lithium, Sodium, Potassium, Rubidium, Cesium, Francium.
Questions about hydrogen
How many valence electrons does hydrogen have?
Hydrogen has 1 valence electron.
How many protons, neutrons and electrons does hydrogen have?
A neutral hydrogen atom has 1 protons and 1 electrons. Its most common form has about 0 neutrons (mass number 1 − 1 protons).
What is the electron configuration of hydrogen?
1s¹, written in short form as 1s¹.
What does the Bohr model of hydrogen look like?
A nucleus of 1 protons and 0 neutrons, circled by 1 electron shell holding 1 electrons.
What is the atomic number of hydrogen?
1. The atomic number is the number of protons in the nucleus, and it is what makes an atom hydrogen.