The valency of oxygen in H₂O (water) is 2.
Understanding Valency in Water (H₂O)
Valency refers to the number of chemical bonds an atom can form with other atoms. In the case of water (H₂O), we can break down the valency of each element:
- Hydrogen (H): Each hydrogen atom in a water molecule shares one pair of electrons, meaning it has a valency of 1.
- Oxygen (O): The oxygen atom in a water molecule shares two pairs of electrons (one with each hydrogen atom). According to the provided reference, "oxygen combines with two hydrogens and so has a valency of 2".
Molecular Structure of Water
The simple diagram of water molecule confirms the following:
- The oxygen atom is centrally located and forms a bond with each hydrogen atom.
- Each hydrogen atom is attached to the oxygen atom through a shared pair of electrons.
Key Points Summarized
| Element | Symbol | Valency | Description |
|---|---|---|---|
| Hydrogen | H | 1 | Each hydrogen atom shares one electron pair with oxygen. |
| Oxygen | O | 2 | The oxygen atom shares two electron pairs, one with each of the two hydrogen atoms. |
Practical Implications
Understanding valency is crucial in predicting how atoms will combine to form molecules. In the case of water, the valencies of hydrogen (1) and oxygen (2) dictate the 2:1 ratio of hydrogen to oxygen in the molecule. This is because the valency of oxygen is 2, and each hydrogen atom has a valency of 1. Thus, two hydrogen atoms are required to satisfy the oxygen's bonding requirements.
