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Top 5 most abundant elements in seawater (by mass)

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Mass fraction of seawater — Materials & element properties

Snapshot · 2026-05-31

  1. 1

    Oxygen

    ~85.8%

  2. 2

    Hydrogen

    ~10.8%

  3. 3

    Chlorine

    ~1.9%

  4. 4

    Sodium

    ~1.1%

  5. 5

    Magnesium

    ~0.13%