Chemistry of life · Topic 5 of 17
Properties of Water
Tap any line to see why it matters
Biology · chemistry of life
Properties of Water
Water is polar, so its molecules hydrogen-bond to each other; that gives cohesion, adhesion, high specific heat, floating ice and strong dissolving power.
01 · PolarityPolar: O end δ−, H ends δ+
02 · H-bondsHydrogen bonds link neighboring waters
03 · Specific heatHigh specific heat steadies temperature
01
What it is
Polar: oxygen end slightly negative (δ−), hydrogen ends slightly positive (δ+) must know
Hydrogen bond = weak pull between δ+ H of one water and δ− O of another must know
Hydrogen bonds → cohesion, adhesion, high specific heat, floating ice, solvent power must know
Cohesion = water attracted to water → surface tension
Adhesion = water attracted to other surfaces → capillary action
Cohesion + adhesion pull water up from roots to leaves
High specific heat: water warms and cools slowly, steadying temperature
High heat of vaporization: evaporating sweat carries heat away
Ice floats: its hydrogen-bond lattice is less dense than liquid water
"Universal solvent": dissolves ions and polar molecules (salt → Na⁺ + Cl⁻)
02
Parts & jobs
H₂O = 2 hydrogens covalently bonded to 1 oxygen, sharing electrons unequally must know
03
Know by heart
Specific heat of water = 1 cal per gram per °C
04
Don't confuse
Hydrophilic = polar, mixes with water; hydrophobic = nonpolar (oils, fats)
05
Cohesion or adhesion?
Commonly confused| Cohesion | Adhesion | |
|---|---|---|
| Attraction between | Water and water | Water and another surface |
| What it causes | Surface tension, beads of water | Capillary action up a thin tube |
| Everyday sign | An insect standing on a pond | Water creeping up a narrow tube |
| Both | From polarity and hydrogen bonds | Together lift water up plant stems |
06
Misconceptions
Trap: most solids sink in their own liquid — ice is the exception
07
More detail
Show 3 more facts
Water ≈ 60–70% of the human body
Most cell chemistry takes place dissolved in water
Water splits slightly into equal H⁺ and OH⁻ → neutral pH 7
Polarity makes hydrogen bonds, and hydrogen bonds explain water's special properties.
Sources · OpenStax Biology 2e §2.2 Water · Union Test Prep — HESI Biology study guide, page 2 (water) · Odessa College Library — HESI A2 guide (Biology list: water) · Built from the verified NurseSavvy HESI A2 fact map (facts reviewed 2026-10-16). HESI is a trademark of Elsevier; NurseSavvy is not affiliated with Elsevier.
Practice this topic, then test the whole section.
HESI and HESI A2 are registered trademarks of Elsevier. NurseSavvy is not affiliated with or endorsed by Elsevier.