Number of Electrons in Oxygen: Quick Facts and Full Guide

The number of electrons in oxygen tells us a lot about how this element behaves in reactions. Whether it’s forming water or rusting metal, oxygen’s electrons play a major role. Let’s break down exactly how many electrons oxygen has—and how they’re arranged.

Quick answer:

A neutral atom of oxygen has 8 electrons.

What is oxygen?

Oxygen is a chemical element with the symbol O and an atomic number of 8. It is a highly reactive nonmetal that forms compounds with many elements. In the atmosphere, oxygen exists as a colorless gas made up of two oxygen atoms—O₂—and makes up about 21% of the air we breathe.

This element is essential for life. Living things use oxygen for respiration, and it’s also involved in combustion, rusting, and other chemical reactions. By mass, oxygen is the third most abundant element in the universe.

How do we find the number of electrons in oxygen?

To figure out how many electrons oxygen has, we look at its atomic number on the Periodic Table of Elements. The atomic number represents the number of protons in the nucleus. Since atoms are neutral, the number of electrons equals the number of protons. Every element, including oxygen, is defined by the number of electrons, protons, and neutrons it contains—and this balance helps us understand atomic structure.

So, for oxygen:

• Atomic number = 8
• Electrons = 8

That means a neutral oxygen atom has 8 electrons.

What about valence electrons?

The outermost shell of electrons in an atom is called the valence shell. These electrons play a key role in chemical bonding.

Oxygen’s electron configuration is

1s² 2s² 2p⁴

This tells us:

• 2 electrons are in the first shell
• 6 electrons are in the second shell (the outer shell)

So, oxygen has 6 valence electrons.

Can oxygen have more than 8 electrons?

Yes—in some forms. When an oxygen atom gains two electrons, it becomes an ion with a charge of -2 (O²⁻). This happens when oxygen bonds with metals or hydrogen. In this state, the oxygen ion has 10 electrons in total—8 from the neutral atom, plus 2 gained.

What else do we know about oxygen atoms?

Here are some of oxygen’s atomic facts:

• Protons: 8
• Electrons: 8 (neutral), 10 (as O²⁻)
• Neutrons: 8 (most common isotope is O-16)
• Electron shells: 2
• Valence electrons: 6
• Oxidation state: usually -2

Its small atomic size and high electronegativity (3.44) make it highly reactive and very effective at forming strong covalent bonds.

Wrapping up

A neutral oxygen atom has 8 electrons—that’s equal to its atomic number. Six of those are valence electrons, which means oxygen tends to gain or share 2 more electrons to complete its outer shell.

The same logic can help you find the number of electrons in other elements: just check the atomic number on the periodic table.