What is the structure and the usage for one of the most basic elements, water? In this IBDP Biology blog we are to understand:
- The molecular structure of water
- Properties of water
- Relationship between water and organisms
Water Molecule
Water is a Polar Molecule
Water is composed of one Oxygen atom and two Hydrogen atoms.Oxygen is electronegative, The Hydrogen atoms are bonded to the Oxygen covalently (sharing electrons) A water molecule is polar.
- This means there is an
- uneven distribution,
- therefore water has a partial
- negative
- charge at the oxygen atom and partial
- positive
- charge at the hydrogen atoms
- The Oxygen atom in a water molecule posseses a
- slight negative charge.
- The Hydrogen in a water molecule posseses a
slight positive charge.
- Hydrogen bonds form between the negative Oxygen of one water molecule and the positive Hydrogen of a different molecule.
- Hydrogen Bonds are attractions between Polar Molecules
Hydrophilic: Substances that are chemically attracted to water
Hydrophilic substances include:
- All substances that dissolve in water such as glucose
- Particles with positve or negative charges such as sodium and cholride ions
- Substances that water adheres to such as cellulose
Hydrophobic: Substances that are insoluble in water
Hydrophobic substances include:
- Substances that do not have positive or negative charges
- Nonpolar substances
- Substances that dissolve in other solvents
Properties
Cohesion: when two water molecules stick together.
- Cohesion allows water to form droplets
- Allows for
- surface tension
- Helps form
capillary action
- Helps form
miniscus
Adhesion: when water molecules stick to a different kind of molecule or surface.
- Helps form miniscus
- Helps form
capillary action
Thermal: High specific heat capacity: It takes alot of energy to change waters temperature.
- Allows for water to have a
- stable temperature
- Allows for
- stable aquatic ecosystems
- Allows for
cooling:
- Sweat coats the hot skin and absorbs the heat needed to
evaporate thereby heating the water and cooling the skin.
Solvent
- Water can
- dissolve
- any polar substance
- Water molecules form a shell around the polar molecules keeping them seperate and in the solution.
- This allows for
transportation of substances in the blood
Relationship between water and organisms
Cohesive properties:
(TRANSPORT)-Helps water go up the xylem of the plant, because of the attraction forces between molecules of the same kind
Thermal properties:
(TRANSPORT)-blood can carry heat to colder places in our body because water requires a lot of energy to warm up but gives off a lot of energy when cooled down
(COOLANT)-plants and animals evaporate water which has cooling effect - water requires a lot of energy to change from a liquid to a gas
Solvent Properties:
(TRANSPORT)-water is polar and dissolves many polar solutes
And that's the end for the properties of water!
Drafted by Venetia (Biology)