Water Flashcards
Benefits of water as a liquid
Provide habitats for living things in rives, lakes and seas
major component of tissue in organisms
reaction medium in chemical reactions
transport medium, eg. blood and vascular tissue
What happens to liquids as they get colder
Becomes more dense until 4 degrees, 4-0 (ice) is less dense as molecules align in a structure less dense than water
Benefits of ice being less dense than water
aquatic organisms have a stable environment throughout winter
ponds and other bodies of water are insulated against cold- reduces rate of heat loss
How does hydrogen bonding occur between water molecules
Polar structure- hydrogen bonds form between neighbouring hydrogen (+) and oxygen (-) atoms of adjacent water molecules (The attraction between individual water molecules creates a bond known as a hydrogen bond.)
Cohesion
When water molecules get close together, oppositely charged parts of the atom attract, forming hydrogen bonds
Surface tension
resistance of external forces, allowing the surface to contract because molecules are being applied to it.
Benefits of water as a solvent
molecules can move around and react together
molecules and ions can be transported around living things whilst dissolved in water (root hairs)
polarity allows water molecules to attract/bind to solute molecules
Benefits of high specific heat capacity
Living things need a stable temperature for enzyme-controlled reactions to happen properly (eg. hydrolysis and condensation)
stable environment for aquatic organisms
small variations in temperature
Benefits of high latent heat of vaporisation
Molecules and held together by hydrogen bonds, so a large amount of energy is needed for water to evaporate
Water can help to cool living things and keep temp stable
eg. sweat and transpiration
Why is water referred to as polar
Oxygen atom in a water molecule has a greater no. protons in nucleus, exerting a stronger attraction for shared electrons
Oxygen atom becomes slightly negative, hydrogen slightly positive
Hydrophilic
substances that can become part of the hydrogen bonded structure and dissolve in water