Yes, oxygen is a pure substance.
Oxygen, represented by the symbol O on the periodic table, is an element and therefore a pure substance. This means it consists of only one type of atom. Pure substances, by definition, have a consistent composition and properties throughout. Oxygen’s atomic mass is 15.99 AMU. Because it is solely comprised of oxygen atoms, it is not a mixture of different substances.
Characteristics of Oxygen as a Pure Substance
- Element: Oxygen is an element found on the periodic table.
- Single Type of Atom: It consists of only oxygen atoms.
- Consistent Composition: Every sample of pure oxygen contains only oxygen atoms with a consistent atomic structure.
- Specific Properties: Oxygen has consistent, predictable properties like its melting point, boiling point, and reactivity.
Why Oxygen Isn't a Mixture
A mixture is made up of two or more different substances physically combined, but oxygen is not. It does not consist of different elements or compounds mingled together. It's fundamentally one type of matter.
| Feature | Oxygen | Mixture |
|---|---|---|
| Composition | Only oxygen atoms | Two or more substances combined |
| Chemical Bonding | Atoms chemically bonded into O₂ molecules | Substances not chemically bonded |
| Separation | Cannot be separated by physical means | Can be separated by physical means |
| Example | Pure oxygen gas | Air (mixture of nitrogen, oxygen, etc.) |
Therefore, since oxygen fits the definition of a pure substance, it's accurate to classify it as such.
