group 7

Question 1

fluorine

Answer 1

pale yellow gas

Question 2

chlorine

Answer 2

yellow green gas

Question 3

bromine

Answer 3

dark red brown liquid

Question 4

iodine

Answer 4

grey black solid

Question 5

astatine

Answer 5

black solid

Question 6

bonding and structure

Answer 6

covalent bonding and elements exist as diatomic molecules with simple covalent structure

Question 7

physical properties

Answer 7

low melting and boiling points so little energy is needed to break the weak london forces between molecules
melting and boiling point increases down the group

Question 8

increase in melting and boiling point down the group because

Answer 8

more shells so more electrons
more london forces between molecules
more energy is required to break the london forces between molecules

Question 9

group 7 elements are powerful

Answer 9

oxidising agents as they remove electrons from another species so get reduced themselves

Question 10

reactivity in group 7

Answer 10

decreases down the group and oxidising power also decreases as you go down
more shells and atomic radius increases
greater shielding effect by inner shell electrons
weaker nuclear attraction on the outer shell electrons
nucleus is less able to attract and capture another electron into its outer shell

Question 11

example of redox reaction

Answer 11

displacement

Question 12

displacement reaction

Answer 12

reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its halide ions

Question 13

displaced halogen

Answer 13

has its own colour so its easy to detect if a displacement reaction has occurred

Question 14

dissolved in water
Cl2
Br2
I2

Answer 14

dissolved in water
pale green
orange
brown

Question 15

dissolved in organic solvent
Cl2
Br2
I2

Answer 15

dissolved in organic solvent
pale green
orange
purple

Question 16

disproportionation reaction

Answer 16

reaction in which the same element is both oxidised and reduced

Question 17

advantage adding chlorine to drinking water

Answer 17

kills bacteria

Question 18

disadvantage adding chlorine to drinking water

Answer 18

chlorine is toxic

Question 19

chlorine reacts with cold and dilute aqueous sodium hydroxide equation

Answer 19

Cl2 (aq) + 2NaOH (aq) –> NaCl (aq) + NaClO (aq) + H2O (l)

Question 20

chemical test for hallide ions

Answer 20

add aqueous silver nitrate to aqueous halide ion solution until precipitate forms
record colour of precipitate
test solubility of the precipitate with dilute and concentrated ammonia solution

Question 21

silver halide precipitate colours

Answer 21

white - AgCl
cream - AgBr
pale yellow - AgI

Question 22

silver chloride

Answer 22

soluble in dilute ammonia

Question 23

silver bromide

Answer 23

insoluble in dilute but soluble in concentrated ammonia

Question 24

silver iodide

Answer 24

insoluble in dilute and concentrated ammonia