Flashcards
Group 7
Cards in this deck (18)
- 1What are the group 7 elements often known as?The Halogens
- 2What is the trend in ionic radius down the group?There is an increase in ionic down the group.
- 3What is the trend in atomic radius down the group?There is an increase in atomic radius down the group.
- 4What is the trend of melting and boiling points down the group?Melting points and boiling points increase down the group due to increasing van der vale between the molecules as the halogen get larger and the number of electrons increase.
- 5How do halogens react?Halogens gain an electron from another species.
They are reduced and the other species is oxidised. - 6What is the trend in reactivity down the group? Why?Reactivity decreases down the group.
-Atomic radius increases down the group.
- There is an increase in electron shielding as number of inner shells increases.
-Effective nuclear charge decreases.
-Less easy for the the element to gain an electron - 7What test can be done to test reactivity of halides and halogens?-Each halogen is mixed with different halides.
-A more reactive halogen will oxidise the halide ion (a displacement reaction).
-As halogens form solutions of different colours then any colour change indicates whether a reaction occurred.
-The mixture is often shaken with a inert solvent e.g. cyclohexane to help intensify the colour. - 8Cl2 + 2Br- ---> state any observationsCl2 + 2Br- ---> 2Cl- + Br2
colour change from green to orange. - 9Cl2 + 2I- ---> state any observationsCl2 + 2I- ---> 2Cl- + I2
colour change from green to brown - 10Br2 + 2Cl ---> state any observationsNo reaction
No colour change - 11Br2 + 2I- ---> state any observationsBr2 + 2I- ---> 2Br- + I2
Colour change from orange to brown - 12I2 + 2Cl- ---> state any observationsNo reaction
No colour change - 13I2 + 2Br- ---> state any observationsNo reaction
No colour change - 14What is the test for halide ions?--The unknown halide is dissolve in water.
-An aqueous solution from silver nitrate is added.
-The silver ions react with the halide ions forming a precipitate.
-The colour intensity of the precipitate formed increases from Cl- to I-.
-The precipitates formed have different solubility in ammonia.
NOTE- Dilute nitric acid may be added before silver nitrate to remove any carbonate ions. - 15What is disproportionation?The oxidation and reduction of the same element in a redox reaction.
- 16Cl2 + H2O --->CL2 + H2O ---> HCl + HClO
- 17Cl2 + 2NaOH --->Cl2 + 2NaOH ---> NaCl + NaClO + H20
- 183Cl2 + 6NaOH --->3Cl2 +6NaOH ---> 5NaCl + NaClO + 3H2O
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- AS - Level Chemistry Flashcards on Group 7, created by Alice Butterworth on 22/02/2016.
- Created by
- Alice Butterworth · Feb 2016
- Updated
- Feb 23, 2016
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