8O15.999
Oxygen
Reactive non-metalsPoor conductors that build the molecules of living things and much of the air.
[He] 2s² 2p⁴
- Atomic number
- 8
- Atomic mass
- 15.999
- Protons
- 8
- Neutrons
- 8 (most common)
- Electrons
- 8
- Shells
- 2, 6
- State at 25 °C
- Gas
- Position
- Group 16, period 2
Proton (+)Neutron (0)Electron (−)
Discovered byCarl Wilhelm Scheele and Joseph Priestley, 1771–1774Carl Wilhelm Scheele: 6 elementsJoseph Priestley: 1 element
Scheele and Priestley both made oxygen by heating compounds. Priestley published first in 1774. Lavoisier named it and explained its role in burning.
Did you know?
- Liquid oxygen is pale blue and is attracted to magnets.
- Almost half of Earth's crust, by mass, is oxygen.
Where it's found
- About 21% of the air
- Water
- Rocks: it is the most common element in Earth's crust
What it's used for
- Breathing, and hospital oxygen
- Steel making
- Welding torches
Try it
Candle under a glassAdult helps
- 1An adult lights a small candle on a plate.
- 2Carefully place a glass jar over it.
- 3Watch the flame.
What you'll see: The flame shrinks and goes out once it has used up the oxygen it needs.