Group 7 Flashcards
(18 cards)
Describe atomic radius down group 7
Increases down the group
Describe reactivity down group 7
Reactivity decreases
Group 7 need to gain an electron
Atomic radius increases
More electrons, more shells more shielding
Weaker forces of attraction between outer electron and positive nucleus
Therefore more harder to gain an electron
Therefore reactivity decreases
Describe ionisation energy down group 7
- ionisation energy decreases down group 7
- atomic radius increases
- more shells, more shielding, more electrons
- weaker forces of attraction between outer electron and positive nucleus
- therefore less energy required to lose an electron
Describe boiling point down group 7
- group 7 elements are simple covalent molecules held together with Van Der Waals forces
- Van Der Waals forces increases down the group as more electrons as you go down the group
- therefore more energy to overcome the Van Der Waals forces
- therefore a higher boiling point as you go down the group
What are oxidising agents? Give an example
Oxidising agents accept electrons from the species being oxidised and are reduced
e.g. halogens
Describe oxidising power as you go down the group
- oxidising power decreases down the group
- as atomic radius gets bigger down the group
- more shells, more shielding, more electrons
- weaker forces of attraction between outer electron and positive nucleus
- therefore it is harder to gain an electron
What are reducing agents? Give examples
Reducing agents - they donate electrons to the species being reduced and are oxidised
e.g. halides
Describe reducing power down group 7
- reducing power increases as you go down the group
- atomic radius increases down the group
- more electrons, more shells, more shielding
- weaker forces of attraction between outer electron and positive nucleus
- therefore it is easier to lose an electron
Describe the test for halid ions
acidified silver nitrate is used to test for halide ions
Observation when we test chloride with acidified silver nitrate, dilute ammonia and concentrated ammonia
+ AgNO3 - white precipitate (AgCl)
+ Dilute NH3 - precipitate dissolves
+ Conc. NH3 - precipitate dissolves
Observation when we test bromide with acidified silver nitrate, dilute ammonia and concentrated ammonia
+ AgNO3 - cream precipitate (AgBr)
+ Dilute NH3 - no change
+ Conc. NH3 - precipitate dissolves
Observation when we test iodide with acidified silver nitrate, dilute ammonia and concentrated ammonia
+ AgNO3 - yellow precipitate (AgI)
+ Dilute NH3 - no change
+ Conc. NH3 - no change
When chlorine reacts with chlorate ions, what does it produce?
Chlorate ions and chloride ions
Explain chlorine used in water treatment processes
- chlorine is used in small quantities to kill bacteria in water treatment process
- poses risks as chlorine is toxic - however benefits of clean, treated water outweigh the risks
Describe how bleach is formed
Chlorine can be mixed with cold, aqueous sodium hydroxide
To produce sodium hypochlorite
2NaOH + Cl2 —-> NaClO + NaCl + H2O
Describe the test for sulfates in group 7
- tested using barium chloride
- reacts to form white precipitate
Describe the test for hydroxides in group 7
- can be identified with red, litmus
- turns blue if positive test
Describe the test for carbonates in group 7
- when an acid is added e.g. HCl, substance containing carbonate ions will fizz (effervescence)
- CO2 gas is given off
- gas can be collected and tested by being bubbled through limewater
- will turn cloudy if gas is CO2
