1.1 chemistry for life

Question 1

what is ionic bonding

Answer 1

when the atoms involved donate or receive electrons to become positive cations or negative anions and the strong forces of attraction between the oppositely charged ions hold the structure together

Question 2

what is covalent bonding. what happens when the molecule is slightly polarised

Answer 2

when the atoms involved in the reaction share electrons to form very strong, neutral bonds
sometimes the molecules are slightly polarised (not evenly shared) and the separation of charge is called a dipole and the structure is called a polar molecule

Question 3

what happens when ionic substances are dissolved in water

Answer 3

the ions dissociate

Question 4

name the formula and use of nitrate ions

Answer 4

NO3 -
needed in plants for the formation of amino acids and proteins

Question 5

name the formula and use of phosphate ions

Answer 5

PO4 3-
needed for the formation of ATP and ADP as well as DNA and RNA

Question 6

name the formula and use of chloride ions

Answer 6

Cl -
needed in nerve impulses and secretory systems

Question 7

name the formula and use of hydrogen carbonate ions

Answer 7

HCO3 -
buffers blood to prevent it from becoming too acidic

Question 8

name the formula and use of sodium ions

Answer 8

Na +
needed for nerve impulses and secretory systems

Question 9

name the formula and use of calcium ions

Answer 9

Ca 2+
needed for the formation of calcium pectate for middle lamella between cell walls
bone formation
muscle contractions in animals

Question 10

name the formula and use of hydrogen ions

Answer 10

H +
cellular respiration
photosynthesis
pH balance

Question 11

name the formula and use of magnesium ions

Answer 11

Mg 2+
needed for chlorophyll production in plants

Question 12

describe how the strong hydrogen bonds form in water

Answer 12

-water consists of two hydrogen atoms and an oxygen
-they’re covalently bonded shared electrons are held closer to the oxygen than the hydrogens
-makes it polar
-slightly positively charger hydrogens are attracted to slightly negative oxygens in other molecules by weak electrostatic attraction, hydrogen bond
weak individually but there are so many they are strong altogether

Question 13

why is water being a polar solvent important

Answer 13

it means that ionic and polar covalent substances can dissolve in it, which is why many chemical reactions take place in it

Question 14

why is water being less dense when frozen important

Answer 14

not common, and when ice is less dense it floats and acts as an insulator for the water sitting underneath it
which helps aquatic organisms in cold places

Question 15

why is water SHC and SLH important

Answer 15

it has a very high SHC and SLH due to the hydrogen bonds so the temperature in large bodies of water isn’t affected by the temperature throughout the year which makes it a great habitat for animals

Question 16

why is water being a liquid important

Answer 16

it means it cannot be compressed, which important for hydraulic mechanisms of living organisms

Question 17

what does water being cohesive and adhesive mean and why are they important factors

Answer 17

cohesive- the molecules stick together
which is important in the movement of water in plants
adhesive- it sticks/ attracted to other molecules
important in plant transport systems

Question 18

why does water have a high surface tension and why is it important

Answer 18

because the attraction between the water molecules is greater than the attraction between the molecules and air
important in plant transport systems and animals that travel on the surface of water