4. inorganic chemistry and the periodic table

Question 1

what do group 2 metals form when they react

Answer 1

2+ ions

Question 2

what happens to the atomic radius of group 2 metals down the group

Answer 2

it increases due to increased electron shells

Question 3

what happens to the reactivity of group 2 metals down the group

Answer 3

it increases due to increased shielding

Question 4

what happens to first ionisation energy of group 2 metals down the group

Answer 4

it decreases due to greater atomic radius and increased shielding

Question 5

what happens when group 2 metals react with water

Answer 5

produces a metal hydroxide and hydrogen.

Question 6

what happens when group 2 metals react with chlorine gas

Answer 6

they form metal chlorides ( white precipitate)

Question 7

what happens when group 2 metals react with oxygen

Answer 7

they form oxides

Question 8

what happens when strontium and barium react with excess oxygen and heat energy

Answer 8

they form metal peroxides

Question 9

what happens when group 2 metals react with dilute acids

Answer 9

produces hydrogen gas and solutions of metal compounds

Question 10

what happens when group 2 hydroxides react with dilute acid

Answer 10

they form a salt and water - neutralisation

Question 11

what happens to the solubility of group 2 hydroxides down the group

Answer 11

they increase

Question 12

what happens to the solubility of group 2 sulfates down the group

Answer 12

they decrease

Question 13

what can you use to test for sulfate ions

Answer 13

barium chloride, it reacts to form barium sulfate which is a white precipitate

Question 14

what group 2 metals undergo thermal decompositions

Answer 14

group 2 carbonates and nitrates

Question 15

how does thermal decomposition occur

Answer 15

heating the substance in lots of oxygen

Question 16

what do group 2 carbonates produce when they undergo thermal decomposition

Answer 16

carbon dioxide and a metal oxide which forms as a white powder

Question 17

what do group 2 nitrates produce when they undergo thermal decomposition

Answer 17

nitrogen dioxide and oxygen with a metal oxide which forms as a white powder

Question 18

what is required as you go down group 2 for thermal decomposition

Answer 18

more heat as the ions increase in size and thermal stability increases.

Question 19

how do group 1 carbonates react in thermal decomposition

Answer 19

they dont decompose upon heating in a lab as they require extremely high temperatures

Question 20

how do group 1 nitrates react in thermal decomposition

Answer 20

they produce a metal nitrite and oxygen.

Question 21

what group 1 element decomposes in the same way as group 2 elements

Answer 21

lithium

Question 22

explanation of thermal stability trend down groups 1 and 2

Answer 22

as you go down the group they form more stable carbonates and nitrates so they require more energy to undergo thermal decomposition.

Question 23

what happens to the charge density as you go down group 1 and 2

Answer 23

it decreases as the ionic radius increases as you go down but the charge stays the same so the charge density decreases.

Question 24

how to carry out a flame test

Answer 24

1. nichrome wire and clean it in concentrated HCL then into a blue flame
2. repeat the cleaning until no colour is produced in the flame
3. dip the wire into the unknown metal compound and place it into the flame
4. observe the colour produced

Question 25

flame colour of lithium

Answer 25

red

Question 26

flame colour of sodium

Answer 26

orange/yellow

Question 27

flame colour of potassium

Answer 27

lilac

Question 28

flame colour of magnesium

Answer 28

no colour

Question 29

flame colour of calcium

Answer 29

brick red

Question 30

flame colour of strontium

Answer 30

crimson red

Question 31

flame colour of barium

Answer 31

pale green

Question 32

how do the colours in the flame tests occur

Answer 32

electron transitions: when energy is supplied by heat, the electrons move to orbitals with higher energy then drop back down to their original orbital. this produces energy in the form of light. the amount of energy released during this is shown through a unique wavelength that produces the colour. if the wavelength produces a colour not on the visible spectrum you will not see a colour emitted.

Question 33

what are group 7 elements

Answer 33

halogens, highly reactive non metals

Question 34

what happens to the atomic radius of group 7 elements down the group

Answer 34

it increases due to additional electron shells

Question 35

what happens to the electronegativity of group 7 elements as you go down the group

Answer 35

decreases as the atomic radius and electron shielding increases meaning the outer electrons are less strongly attracted to the nucleus and can be removed easier

Question 36

what happens to the melting and boiling points down group 7

Answer 36

it increases. they are simple covalent molecules that are held together by london forces. as the relative atomic mass increases, the amount of london forces increases meaning more energy is required to overcome them.

Question 37

what happens to reactivity down group 7

Answer 37

it decreases due to the increased distance from the nuclei to the outer electrons, this increases atomic radius and increased shielding makes it harder to attract electrons to react.

Question 38

why are group 7 good oxidising agents

Answer 38

the oxidising power decreases down the group so the halogen will replace the halide beneath it. cl2 can displace br- and br2 will displace i-

Question 39

what is a halide ion

Answer 39

a negative ion of a halogen

Question 40

halide ions are good reducing agents what happens to reducing power down the group

Answer 40

it increases a electrons are easier to lose and they form larger ions due to shielding and larger atomic radius

Question 41

how to distinguish halide ions

Answer 41

1. add acidified silver nitrate Cl- white precipitate Br- cream precipitate I- yellow precipitate Can be tested further by using dilute and concentrated ammonia

Question 42

what happens when a hydrogen halide reacts with ammonia gas

Answer 42

forms ammonia salts

Question 43

what happens when hydrogen halides react with water

Answer 43

form dilute acids

Question 44

how to test for sulfate ions

Answer 44

acidified barium chloride - white precipitate produced. barium sulfate

Question 45

how to test for carbonate and hydrogencarbonate

Answer 45

add HCl - bubbles produced collect gas and bubble through limewater, limewater turns cloudy if CO2 is present

Question 46

test for ammonium ions

Answer 46

add NaOH and gently warm to produce ammonia gas. hold damp red litmus paper over the substance and it will turn blue if ammonium ions are present