4.2 - Group 7

Question 1

what are halogens

Answer 1

group 7 elements

Question 2

what type of bonding and substances are halogens

Answer 2

covalent bonding
simple moleculular substances

Question 3

what are the properties of group 7 elements

Answer 3

all are diatomic
colours get darker down the group
MP/BP increases down the group

Question 4

what colour is fluorine

Answer 4

very pale yellow

Question 5

what state is fluorine

Answer 5

gas

Question 6

what colour is chlorine

Answer 6

pale green

Question 7

what state is chlorine

Answer 7

gas

Question 8

what colour is bromine

Answer 8

brown

Question 9

what state is bromine

Answer 9

liquid

Question 10

what is bromine like

Answer 10

volatile, releases brown fumes

Question 11

what colour is iodine

Answer 11

dark grey

Question 12

what state is iodine

Answer 12

solid

Question 13

what is iodine like

Answer 13

sublimes, releases purple fumes

Question 14

what colour is astatine

Answer 14

black

Question 15

what state is astatine

Answer 15

solid

Question 16

what happens when halogens react with metals

Answer 16

they form ionic compounds

Question 17

what happens to the electrons in a halogen and metal reaction

Answer 17

the outer shell electrons are transferred to the halogen

Question 18

what type of reaction is a halogen and metal reaction

Answer 18

redox

Question 19

why does the halogen change its name and what to in a halogen and metal reaction

Answer 19

it changes from a halogen to halide
so chlorine would go from chlorine atom to chloride ion

Question 20

what happens to the reactivity of halogens down the group

Answer 20

they get less reactive

Question 21

what do all halogens need to do to fill their outer shell

Answer 21

gain an electron

Question 22

why is it easier for halogens to gain an electron and form a halide ion further down the group

Answer 22

atoms have more electron shells
the extra electron is further from the nucleus
so its attraction to the nucleus is weaker

Question 23

what is the chemical test for chlorine

Answer 23

damp blue litmus paper turns white
– because the chlorine acts as a bleaching agent so it removes the colour from the paper

Question 24

what do more reactive halogens do to less reactive halogens when they react

Answer 24

they can displace the less reactive halogens

Question 25

what colour is Cl2 (aq)

Answer 25

colourless

Question 26

what colour is Br2 (aq)

Answer 26

yellow

Question 27

what colour is I2 (aq)

Answer 27

brown

Question 28

what colour is the salt KCl

Answer 28

colourless

Question 29

what colour is the salt KBr

Answer 29

colourless

Question 30

what colour is the salt KI

Answer 30

colourless

Question 31

what is the reaction between KCl and Br2

Answer 31

no change
stays yellow

Question 32

what is the reaction between KCl and I2

Answer 32

no change stays brown

Question 33

what is the reaction between KBr and Cl2

Answer 33

Cl2 + 2KBr –> Br2 + 2KCl
chlorine displaces bromine
colourless –> yellow

Question 34

what is the reaction between KBr and I2

Answer 34

no change
stays brown

Question 35

what is the reaction between KI and Cl2

Answer 35

Cl2 + 2KI –> I2 + 2KCl
chlorine displaces iodine
colourless –> brown

Question 36

what is the reaction between KI and Br2

Answer 36

Br2 + 2KI –> I2 + 2KBr
bromine displaces iodine
yellow –> brown

Question 37

what is the reactivity trend of chlorine, bromine and iodine

Answer 37

chlorine> bromine> iodine

Question 38

what is the colour change due to

Answer 38

the halogens present because the salts are colourless

Question 39

what does the more reactive halogen do to the halide

Answer 39

the more reactive halogen atom steals an electron from the halide ion in the salt