Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table and is a highly reactive nonmetal and oxidizing agent that readily forms compounds (notably oxides) with most elements. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium.
Three reasons Oxygen stands out
1
Essential for respiration and combustion.
2
It is the most abundant element in the Earth's crust by mass.
3
In liquid form it is a pale blue colour and is strongly attracted to magnets.
The reactive partner behind respiration
Oxygen’s appetite for electrons makes combustion possible and lets cells release energy from food. Photosynthetic organisms continually replenish atmospheric oxygen, but the element also dominates Earth’s crust by mass inside silicate minerals and oxides. Its pale-blue liquid form is visibly drawn toward a strong magnet.
Recognizing Oxygen in Elementle
If Oxygen is the mystery element, guesses below atomic number 8 point up and guesses above it point down. Its symbol is O: a green letter matches the same position in that symbol, while a yellow letter belongs in another position.
The family clue turns green for nonmetal guesses. Compare Nitrogen (N), number 7 and Carbon (C), number 6: they share the family clue, but their atomic numbers and symbols help you tell them apart.
Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.
The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.