Water and Hydrogen Bonding

Question 1

The shared electrons in water are not shared evenly. The oxygen atom in the molecule pulls the shared electrons towards it, so the oxygen becomes slightly negatively charged and teh hydrogens slightly positive. As a consequence of this, what kind of molecule is water?

Answer 1

A polar molecule.

Question 2

What kinds of bonds form between water molecules?

Answer 2

Hydrogen bonds.

Question 3

Why do we sweat when we’re hot?

Answer 3

Because the evaporation of water uses up a relatively large amount of energy. This means that water evaporating from a surface ‘removes’ heat from that surface. So heat energy is used in evaporation.

Question 4

Is ice more or less dense than water?

Answer 4

Less dense.

Question 5

What does cohesion mean?

Answer 5

When molecules of teh same type stick together. Water molecules are cohesive because hydrogen bonds pull water molecules in at the surface. That’s why you see water droplets on leaves.

Question 6

Water is a good solvent. What kind of molecules dissolve in water?

Answer 6

Polar molecules.

Question 7

List some of the main properties of water.

Answer 7

1. Solvent
2. Liquid transport medium for movement of materials around organisms
3. Cohesion
4. Freezing
5. Thermal stability - large water bodies have fairly constant temperatures as it takes more energy to heat up water than air due to the hydrogen bonds absorbing energy
6. Metabolic - water takes part as a reactant in some chemical processes