A1.1 Water Flashcards
Water structure
Water (H2O) is made up of 2 hydrogen atoms covalently bonded to an oxygen atom.
Water is described as polar because the oxygen atom is slightly negative (δ–) while the hydrogen atoms are slightly positive (δ+).
Water can form hydrogen bonds with other water molecules (between a δ+ hydrogen and a δ– oxygen of two molecules).
Water properties
Solvent properties
Cohesion
Adhesion
High heat capacity
High latient heat
theramal conductivity
buoyancy
viscosity
solvent properties
- Able to dissolve charged particles (due to the partially positive H and partially negative O)
Act as a good metabolic and transport medium.
cohesion
- Strong hydrogen bonds between water molecules, creating surface tension
- Allowing organisms to walk on water surface
adhesion
- Water molecules weakly stick onto the walls of container
- Allowing capillary effect in the xylem tube
High heat capacity
- It takes a lot of energy to change the temperature of water
- Keeping a relatively stable aquatic temperature
High latentheat
- It takes a lot of energy to evaporate_water
- Useful as a_coolant_(e.g. sweating)
Thermal Conductivity
- Water absorbs and transfers heat more readily than air as water particles are packed tightly together
- blood transport heat around the body, water currentdistributing heat around the globe
Buoyancy
- Water applies a greater upward force_than air
- Allows organisms to float_ in water
Viscosity
- Water is more viscous_than air
- Increase the friction of flowing molecules
Examples of the Biological Consequences of Water
Black-throated loon
Ringed Seal:
Black-throated loon
Buoyancy: hollow bones and are less dense, allowing loon to float
Viscosity: Legs are _located at the rear_to better propel them through water
Thermal conductivity: Feathers form an _interlocking structure_that functions as a barrier to water, _preventing heat loss_by the current
Ringed Seal
Buoyancy: _denser bones allowing it to stay submerged upon diving
Viscosity: streamlined body to better propel them through water
Thermal conductivity: _outer coat of fur that traps air and thick layer of blubber to present heat loss in water
Specific heat capacity: Do not have many __effective calling mechanisms_because water temperature are generally stable.
The Origin of Water on Earth
Hypothesis:
- Early stage of earths surface was nothing other than magma
- Over very long periods of time earth cold and numerous asteroid struck the earth bringing hydrated minerals that released water
- The asteroids became part of the earths crust