water

Question 1

structure of water

Answer 1

each hydrogen shares a pair of electrons with oxygen, oxygen has larger positive charge so the electrons moved towards it, creating slight negative charge= polar

Question 2

electronegativity value

Answer 2

oxygen higher than hydrogen- tendancy of atom because its charged to attract a bonding pair of electrons

Question 3

dipole molecule

Answer 3

water is dipole- uneven charges means it has slight positive and slight negative charge, making it polar

Question 4

cohesion and surface tension

Answer 4

-water molecules attracted to water molecules beneath more than air above bc hydrogen bonds
-this contracts the surface of the water (pulls molecules inwards) so the surface can resist downwards force

Question 5

application of cohesion

Answer 5

-water travels up through xylem, water molecules pulled in one continuous motion as they’re joined by hydrogen bonds- adhesion to xylem walls and cohesion to water

Question 6

cohesion vs adhesion

Answer 6

cohesion- molecules attracted to same molecules
adhesion- molecular attraction of diff molecules

Question 7

density of water as it turns into ice

Answer 7

hydrogen bonds form a regular hexagonal, crystalline structure so take up more space as molecules spread further apart, making it less dense than water

Question 8

advantages of water density

Answer 8

-allows ice to float to form a insulating layer protecting underwater animals

Question 9

water polarity

Answer 9

positive and negative sides of a water molecule are attracted to positive and negative ions

Question 10

water polarity application

Answer 10

act as a solute for biochemical reactions

Question 11

why does water have a high specific heat capacity

Answer 11

due to hydrogen bonding, molecules are held together tightly, a lot of energy needed to increase kinetic energy of molecules and break them apart

Question 12

appication of specific heat

Answer 12

how mammals cool themselves, evap uses heat energy making you become cooler

Question 13

examples of the function of water

Answer 13

-its a reactant in many chemical reactions e.g. hydrolysis
-its a solvent, most biological reactions take place in a solution (e.g. cytoplasm of euk and prok cells)
-transportation of substances
-helps with temperature control because of its high specific heat capacity
-is a habitat for organisms

Question 14

why is water a habitat for organisms

Answer 14

-it helps with temperature control
-is a solvent
-becomes less dense when it freezes

Question 15

in what direction are electrons pulled

Answer 15

-towards the oxygen atom
-leaving the other side of each hydrogen atom with a slight positive charge

Question 16

what do hydrogen bonds give water

Answer 16

-a high latent heat of evaporation
-a high specific heat capacity

Question 17

how is the high latent heat of evaporation useful for living organisms

Answer 17

-takes a lot of energy to break the hydrogen bonds
-so a lot of energy is used up when water evaporates
-means water is good for cooling e.g. when sweat evaporates from the surface of the skin

Question 18

explain how waters polarity makes it a good solvent

Answer 18

-a lot of important substances in biological reactions are ionic (one positive and one negative atom e.g. salt)
-because water is polar, the slight positive end of a water molecule will be attracted to the -ve ion and the slight negative end will be attracted to a +ve ion
-means they will dissolve

Question 19

what makes ice less dense than water

Answer 19

-water molecules in ice are held further apart as each water molecule forms four hydrogen bonds
-making a lattice shape