8
O
Nonmetal

Oxygen

Atomic number 8 · Period 2 · Block P

O · Oxygen
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Understanding the element

Oxygen (O) is chemical element 8. It belongs to the nonmetals, and its reference state at room temperature is a gas. Those basic facts are a useful starting point for its chemistry and applications.

Where do we encounter it?

In practice, it turns up most often in respiration, metallurgy and steel and water treatment.

respirationmetallurgy and steelwater treatment
Standard atomic weight[15.99903, 15.99977]

What its position in the table tells us

Oxygen sits in period 2, group 16 and the P block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.

Worth remembering
Oxygen has a characteristic place in the periodic table that helps explain both its chemistry and its practical uses

Scientific sources

Element identity
Atomic number8
Group16
Period2
BlockP
CategoryNonmetal
PhaseGas