A1.1 - water

where are the first cells originated

formed and evolved in ocean

why is water the medium of life

it provides the solvent cells needed for biochemical reactions to occur

how does metabolism occur

it can only occur when the starting materials are in the watery environment of the cell

what is the main structure of a water molecule

1 oxygen atom and 2 hydrogen atoms

what is electronegativity

it measure how strongly the nucleus of an atom attracts the electrons it shares with another atom

what are the two factors that could affect electronegativity

1) number of protons in the nucleus
2) number of orbital levels in the atom

oxygen is more / less electronegative than hydrogen

more

water molecule is a ____ molecule

polar

what is polar covalent bond

the uneven sharing of electrons

how does cohesion happen

the hydrogen bonds lead to strong cohesive force that causes the water molecules to stick together

what is cohesion

water molecules are attracted to each other

cohesive forces

high surface tension

define adhesion

water molecules are attracted to other polar or charged substances by forming hydrogen bonds

define capillary action

forces that draws water from wetter areas to drier areas

what does capillary action do

- maintain soil hydration
- promote even distribution of nutrients

what is the properties of water in the transport of water under tension in the xylem of plants

cohesion + adhesion

what charge is the hydrogen atoms in water

partially positive

what charge is the oxygen atoms in water

partially negative

what are the bonds between the hydrogen and oxygen atoms in a water molecule

polar covalent bond

define solvent

a liquid that dissolves something

define solute

something that will dissolve in a liquid

define solution

the product of something dissolving in a liquid

what molecules do water dissolve

polar / ionic

why is water the medium for metabolism

water helps in the transport of reactants and removal of by-products, most enzymes catalyze these reactions and it is operated in aqueous solutions

what is the transportation in plants of water

water dissolves nutrients and carries them from the soil to the plant cells through the xylem

what is the transportation in vascular tissue of water

phloem - uses water as the medium to transport sugars and other metabolic products from the leaves to the other parts of the plant

what is the transportation in animal of water

blood - transport nutrients, hormones and waste products

why is water a universal solvent

it dissolves more substances than anything else on earth

what are the properties of hydrophobic

- cannot dissolve in water
- non-polar

what are the properties of hydrophilic

- can dissolve in water
- polar

what are the 3 thermal properties of water

latent heat, specific heat capacity, thermal conductivity

latent heat

- absorbs / release heat when changing state
- water has high latent heat of vaporization
- absorbs a large amount of heat energy while changing from liquid to gas

specific heat capacity

- absorbs a lot of heat energy without its temperature increases
- the heat energy needed to raise the temperature of 1g of water by 1C
- water has a high specific heat capacity

thermal conductivity

- the ability of a material to conduct heat
- water has a high thermal conductivity

what are the three chemical properties of water

- cohesion
- adhesion
- solvent

what are the six physical properties of water

- specific heat capacity
- thermal conductivity
- buoyancy
- transparency
- viscosity
- latent heat

buoyancy

- counteracts the force of gravity
- water has high buoyancy compared to air

viscosity

- high viscosity -> more friction when moving through it
- water has a high viscosity

where does water come from

asteroids

define goldilocks zone

the habitable area around a star for liquid water to exist on the surface of a planet
(its not too hot / too cold for water in liquid state)