Question

at the molecular level, what gives water its high surface tension?
1 at the surface, water molecules align in a repeating crystalline pattern that increases the number of hydrogen bonds significantly.
2 at an interface between water and air, water is repelled by the air, which pushes surface water molecules together, creating a denser area of water at the surface.
3 at the surface, water is only surrounded on some sides by other water molecules, so more bonding occurs between molecules along and just below the surface, creating a skin of water that resists rupture.
4 water molecules are spread more thinly across the surface of a droplet. stress is placed on the hydrogen bonds as water molecules are spread further apart, causing tension.
difficulty: iii
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Explanation:

To determine what gives water its high surface tension at the molecular level, we analyze each option:

• Option 1: Water at the surface doesn't form a repeating crystalline pattern (that's ice), so this is incorrect.
• Option 2: Air doesn't repel water molecules to create a denser area; water molecules are attracted to each other, so this is incorrect.
• Option 3: At the water - air surface, water molecules are only surrounded by other water molecules on some sides (below and to the sides, not above). This means the cohesive forces (due to hydrogen bonding) between the water molecules at the surface are stronger because there are no water molecules above to interact with. This creates a "skin" effect, which is surface tension. So this option correctly explains the molecular basis of surface tension.
• Option 4: Spreading water molecules further apart would decrease, not increase, surface tension. So this is incorrect.

Answer:

1. At the surface, water is only surrounded on some sides by other water molecules, so more bonding occurs between molecules along and just below the surface, creating a "skin" of water that resists rupture.