A1.1 Water

Question 1

Electronegativity

Answer 1

An affinity to electrons

Question 2

Hydrogen bonds

Answer 2

Strong intermolecular forces formed as a because of the polar covalent bonds within water molecules.
- Form when a δ+ hydrogen atom is attracted to a δ– fluorine, oxygen or nitrogen atom of another molecule
- Hydrogen bonds are stronger than standard polar bonds due to the relatively high electronegativity of F, O and N

Question 3

Dipolar molecule

Question 4

Cohesion

Answer 4

The attraction between like molecules

Question 5

Adhesion

Answer 5

The attractive force between different types of molecules

Question 6

An example of cohesion in water molecules

Answer 6

Xylem -

Question 7

An example of adhesion in water molecules

Answer 7

Xylem -

Question 8

Polar bonds

Answer 8

A type of covalent bond between two atoms in which electrons are shared unequally

Question 9

Polarity

Answer 9

The slight difference in charge that occurs at the different poles of the water molecule

Question 10

What is caused by oxygen’s electronegativity?

Answer 10

A stronger attraction to electrons which forms a slightly negative charge (δ–)

Question 11

What does hydrogen’s weaker attraction to electrons cause?

Answer 11

A slightly positive charge (δ+)

Question 12

Properties of water

Answer 12

Cohesion, adhesion, surface tension, and capillarity, buoyancy, viscosity, thermal conductivity and specific heat capacity

Question 13

How can water striders move along the surface of the water?

Answer 13

• Distribute their weight via long legs that contain thousands of microscopic hairs to trap air and increase buoyancy
• High surface tension of water makes it sufficiently dense for certain smaller organisms to move along its surface