Molecular bonding and properties of water

The 2 types of reactions

Condensation and hydrolysis

Describe what a condensation reaction is

Reactions where water is released to combine something

Describe what a hydrolysis reaction is

Reactions where water is consumed to break something apart

Monomer

A single small unit, which can combine together to form a larger polymer

Polymer

A large molecule that’s made up of many small monomers

Hydrogen bond

A weak bond that forms when a slightly negative ion is attracted to a slightly positive ion

Peptide bond

A bond between 2 amino acids

Glycosidic bond

A bond between 2 carbohydrates

Ester bond

A bond between a glycerol and fatty acid chain

Describe the structure of a water molecule

Water consists of 2 hydrogen atoms and an oxygen covalently bonded together. The oxygen molecule has more protons in its nucleus so it would exert a greater of force of attraction for the electrons, causing the oxygen atom to be slightly more negative and the hydrogen will be slightly more positive.

Why is water denser as a liquid than as a solid and why is it useful in nature?

When water freezes, it aligns itself in a structure, which is less dense than liquid water.

Its useful for nature because ice will float on top of water so it:

• acts as another habitat for animals(e.g. polar bear)

• insulates the water below

Why is water a good solvent and why does that make it useful for nature?

Water is a good solvent because of its polar nature, water molecules have both a pos/neg charge, which is attracted to both neg/pos molecules, allowing it to cluster around and keep the molecules separate.

This is useful for nature because:

• Cellular reactions take place in the cytoplasm, which is 70% water

• Dissolved molecules and ions can be transported around living things in water

Why is water cohesive and why does that male it useful for nature?

Water does not spread out when dripped onto a surface because the hydrogen bonds between the molecules pull it together.

This is useful in nature because:

• Water can be pulled up in one smooth motion in the xylem of plants

• Insects like pond-skaters can ‘walk’ across water

What does it mean that water has a high specific heat capacity and why is it useful in nature?

It takes a lot of energy to raise the temperature of water because a lot of energy is needed to overcome all the hydrogen bonds, which hold the molecules together.

This is useful in nature because:

• Aquatic environments are a stable habitat for animals to survive in

• Enzymes have a stable temperature to work in