H₂O is bent (about 104.5°). Oxygen pulls the shared electrons closer, so it is slightly negative (δ−) and the hydrogens slightly positive (δ+). Opposite charges on neighbouring molecules attract: hydrogen bonds.
💧 Cohesion & surface tensionHydrogen bonds pull water molecules together, letting insects walk on water and drops bead up.
🌡️ High heat capacityWater absorbs lots of heat before warming up (4.18 J/g°C), so oceans keep coastal climates mild.
🧂 Universal solventPolar water pulls apart ions and polar molecules, so more substances dissolve in water than in any other common liquid.
🌳 Adhesion & capillary actionWater sticks to other surfaces and climbs thin tubes, helping move water up plant stems.
🧊 Expands when frozenIce is less dense than liquid water, so lakes freeze from the top down and fish survive winter.
🔥 High boiling pointFor such a small molecule, water boils at a very high 100°C because of hydrogen bonds.