Diatomic
Definition and meaning of Diatomic in chemistry.
Diatomic describes a molecule made up of exactly two atoms, bonded together covalently. These atoms may be identical (homonuclear, like O2) or different (heteronuclear, like CO).
In more detail
Seven elements exist as diatomic molecules in their standard elemental form: hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine (H2, N2, O2, F2, Cl2, Br2, I2). This matters in stoichiometry, since balanced equations must use these two-atom formulas rather than single atoms for these elements. The two atoms are held together by a single, double, or triple covalent bond, depending on the element or compound; nitrogen's N2, for instance, has a strong triple bond that makes it relatively unreactive at room temperature.
Key facts
| Field | General Chemistry |
|---|---|
| Common diatomic elements | H2, N2, O2, F2, Cl2, Br2, I2 |
| Bonding | Covalent (single, double, or triple) |
| Example formula | O2 (homonuclear), HCl (heteronuclear) |
Oxygen gas, O2, is a homonuclear diatomic molecule and makes up about 21% of Earth's atmosphere by volume.
Frequently asked questions
What are the seven diatomic elements?
Hydrogen (H2), nitrogen (N2), oxygen (O2), fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2) all exist as two-atom molecules in their standard elemental form.
What is the difference between homonuclear and heteronuclear diatomic molecules?
Homonuclear diatomic molecules contain two atoms of the same element, such as N2 or Cl2. Heteronuclear diatomic molecules contain two different elements, such as CO or HCl.