GROUP 7

Question 1

what colour is F2

Answer 1

pale yellow gas

Question 2

what colour is CL2

Answer 2

green gas

Question 3

what colour is Br2

Answer 3

red brown liquid

Question 4

what colour is I2

Answer 4

black solid

Question 5

trends in melting point

Answer 5

increases down the group, as molecule get larger they have more electrons so increasing number of shells and the nucleus is able to attract to bonding pair of electrons

Question 6

trends in electronegativity

Answer 6

relative tendency of an atom in a molecule to attract electrons in a covalent bond to itself

Question 7

what is a halogen

Answer 7

strong oxidising agent that will displace a halogen with lower oxidising power from its compounds, the oxidising strength decrease down the group, oxidising agent are electron acceptors

Question 8

what is a displacement reaction

Answer 8

a more reactive halogen will displace a halide ion of less reactive halogen from the solution

Question 9

appearance of chlorine in water

Answer 9

pale green

Question 10

appearance of bromine in water

Answer 10

orange

Question 11

appearance of iodine in water

Answer 11

brown

Question 12

appearance of AgCL

Answer 12

white precipitate and dissolve to colourless

Question 13

appearance of AgBr

Answer 13

cream precipitate and does not dissolve in dilute ammonia however in concentrated ammonia it will be colourless

Question 14

appearance of AgI

Answer 14

yellow precipitate and does not dissolve

Question 15

trend of halides as reducing agent

Answer 15

the halides show increasing power as reducing agent as one goes down the group because as a reducing agent donates electrons the reducing power of the halides will increase down group 7 so have a greater tendency to donate electrons because ions get bigger and it is easier for outer electrons to be given away as they pull from the nucleus and get smaller

Question 16

chlorine in water

Answer 16

dissolves in water to form hydrochloric acid and chloric acid

Question 17

what is chloric acid used for

Answer 17

oxidising agent that kills bacteria and sanitises water

Question 18

what is sodium chlorate used for

Answer 18

it has a bleaching action which allows it to be an active ingredient in household bleach

Question 19

what is the advantages of using chlorine to treat water

Answer 19

it prevents the spread of waterborne diseases and sanitises water, although it has respiratory irritants and could react to form chlorinated hydrocarbons the benefit of health outweighs the toxic effects