Group 7 Flashcards
Trend of electronegativty down group 7
The further down the group, the lower the electromagnetically, more shielding, further from nucleus
Trend in atomic radius down group 7
Further down, atomic radius increases
Trend in melting/boiling points down group 7
Further down, melting and boiling point increases as each molecule as more electrons, increasing Van Der Waals forces. This occurs due to them being diatoms
Trend of oxidising ability down group 7
Oxidising ability decreases down the group
Why would chlorine displace iodide ions
Chlorine is a better oxidising agent than iodine
Trend of reducing ability down group 7
Reducing ability increases as you go down the group.
Proof of the trend of reducing ability of group 7
Fluoride and chloride ions won’t reduce concentrated sulphuric acid
What is the test for halide ions
Add silver nitrate and nitric acid to a solution of the sample. Chlorine is white precipitate, bromine is cream, iodine is yellow
Why is silver nitrate solution used to identify halide ions
Silver Chloride, bromide and iodide are insoluble
Why is nitric acid used
The nitric acid reacts with, and removes, other ions that might also give a confusing precipitate with silver nitrate
Why can this test not be used for fluoride ions
Silver fluoride is soluble
Why is ammonia solution added after the silver nitrate test
To distinguish between silver bromide and silver iodide as they have similar colours
Observation with silver chloride and ammonia solution
Precipitate dissolves to give a colourless solution
Observation with silver bromide and ammonia solution
Dissolves in ->concentrated
Observation with silver iodide and ammonia solution
precipitate is insoluble in ammonia solution of any concentration
