2.3 Group 7 (Halogens) Flashcards
What are the group 7 elements like in terms of reactivity
Highly reactive
How deos the atomic radius of group 7 change as you go down the group
As you go down the group the atomic radius increases, because of the additional shells
How does the ionisation energy change as you go down group 7
Ionisation energy decreases as you go down, because the atomic radius icnreases, so the attraction between outer electron and the nucelus is weaker, making it easier to lose
How does reactivity change as you go down group 7
Need to gain one electron
as atomic radius increases it becomes ahrder as the positive charge from the nucelus is weakened by additional shielding
harder to attract an electron
therefore reacitivty decreases
How does boiling point change as you go down group 7
Group 7 are simple covalent molecules, held by Van Der Waals
As the Ar increases, the opportunity for Van dr Waals increases down the group
meaning more energy required to overcome then,
therefore increasing the boilin gpoint as you go down the group
How does oxidising power change as you go down the group
Oxidising power decreases down the group
because their ability to attract electrons becomes weaker
due to shielding and greater atomic radius
Halogens = good …
Halide ions = good …
Halogens are good oxidising agents
Halide ions are good reducing agents
How does reducing power change as you go down the group of the halide ions
Reducing power increases as you go down
electrons easier to lose from larger ions
due to shielding and increased atomic radius
therefore easier to donate electrons to the thing being reduce and them themselves are oxidised
What do you use to test for halide ions
Acididfed silver nitrate
After doing the silver nitrate test, what do you use to further distinguish
Ammonia
State the chlorine ions reactions when tested for halide ions
Chlorine + Silver nitrate = White precipitate
+ dilute NH3 = precipitate dissolves
+ Conc. NH3 = precipitate dissolves
State the Bromine ions reactions when tested for halide ions
Bromine +Silver Nitrate = Cream Precipitate
+ dilute NH3 = No change
+ conc. NH3 = Precipitate dissolves
State the Iodide ions reactions when tested for halide ions
Iodine + Silver Nitrate = Yellow Precipitate
+ dilute NH3 = no change
+ conc. NH3 = no chnage
How do you test for sulfate ions
add BaCl2, which forms a white precipitate
How do you test for hydroxide ions
(which means alkaline)
- Red litmus paper turning blue
- Universal indicator turning blue-purple
