Seawater is predominantly water (H₂O) but also contains significant amounts of dissolved salts, primarily sodium chloride, and trace amounts of other elements. The chemical composition can be described by the elements present and their relative percentages by mass.
According to the provided reference, the major elements by percent by mass are:
Major Elements in Seawater by Mass
| Element | Percent by Mass |
|---|---|
| Oxygen | 85.84 |
| Hydrogen | 10.82 |
| Chlorine | 1.94 |
| Sodium | 1.08 |
These percentages highlight that oxygen and hydrogen constitute the vast majority of seawater's mass, as expected from the water molecule (H₂O). The next most abundant elements are chlorine and sodium, which combine to form sodium chloride (NaCl), common table salt, the primary dissolved solid in seawater.
While these four elements make up over 99.5% of the total mass, seawater also contains numerous other elements in smaller concentrations, which contribute to its unique properties and support marine life.
For more detailed information, you can refer to the Seawater - Wikipedia page.
