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Why does water have unusually high surface tension?

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water rapids, Niagara Falls, Canada — water Water is the most plentiful compound on Earth and is essential to life. Although water molecules are simple in structure (H₂O), the physical and chemical properties of water are extraordinarily complicated.

Water exhibits an unusually high surface tension primarily due to the unique electronic structure of its molecules and the resulting hydrogen bonds.1

Because the oxygen atom is more electronegative than the hydrogen atoms, the O–H bonds in a water molecule are polar. This creates a partial negative charge on the oxygen and a partial positive charge on the hydrogens. Consequently, the hydrogen atoms of one water molecule are attracted to the unshared electron pairs of the oxygen atom on adjacent molecules, forming weak linkages known as hydrogen bonds.1

In liquid water, these molecules form continually shifting aggregates held together by this short-range order. This cohesive network of hydrogen bonds requires significant energy to disrupt, which manifests as high surface tension—the property that allows the liquid surface to act like a stretched elastic membrane.12