Oxygen (O): Bohr Model, Protons, Neutrons & Electrons
Oxygen is element number 8, a nonmetal in group 16, period 2. Its atom has 8 protons, 8 neutrons and 8 electrons arranged in 2 shells: 2, 6.
Protons, neutrons and electrons in oxygen
The atomic number of oxygen is 8, so every oxygen atom has 8 protons. A neutral atom has the same number of electrons, 8. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For oxygen-16, that is 16 − 8 = 8 neutrons. Oxygen has 3 stable isotopes, with 8, 9, 10 neutrons.
How to draw the Bohr model of oxygen
- Draw the nucleus and write 8 p⁺ and 8 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 6 electrons on it.
- Check: 2 + 6 = 8 electrons, the same as the number of protons.
Electron configuration
The electron configuration of oxygen is [He] 2s² 2p⁴. Its 6 outer electrons decide how it reacts: it tends to gain 2 more, forming O²⁻ ions.
Key facts about oxygen
| Symbol | O |
|---|---|
| Atomic number | 8 |
| Relative atomic mass | 15.999 |
| Group · period · block | group 16 · period 2 · p-block |
| Type | Nonmetal |
| State at 25 °C | gas |
| Electron shells | 2, 6 |
| Electron configuration | [He] 2s² 2p⁴ |
| Valence electrons | 6 |
| Common ion | O²⁻ |
| Electronegativity (Pauling) | 3.44 |
| First ionisation energy | 13.62 eV (1314 kJ/mol) |
| Atomic radius (empirical) | 60 pm |
Where oxygen sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does oxygen have?
Oxygen has 8 protons and 8 electrons (atomic number 8). Its most common isotope, oxygen-16, has 16 − 8 = 8 neutrons.
What is the electron configuration of oxygen?
[He] 2s² 2p⁴. In shells that is 2, 6.
How many valence electrons does oxygen have?
6. Oxygen is in group 16, and its outer shell holds 6 electrons.
Where is oxygen on the periodic table?
In group 16, period 2, in the p-block. It is a nonmetal.
