C10 - Group 7 Flashcards
What happens to the boiling point down group 7?
It increases
Why does group 7 boiling point increase down group 7?
The size of the atom increases, with more electrons which means there are stronger Van der Waals forces of attraction between molecules, takes more energy to break them
What happens to electonegativity down group 7 and why?
It decreases because there is a greater atomic radius means lower force of attraction between nucleus and electron pair in a covalent bond
What is the trend of reactivity of the halogens as you go down the group?
It decreases
What is the trend in oxidising ability down group 7 and why?
It decreases
Because Cl has the fewest occupied electron shells and greatest force of attraction between outer electrons and nucleus so is easiest to gain electrons and be reduced so therefore best oxidising agent
What do halogens react with oxygen to form?
Hydrogen halides
E.g. HCl
What is the name of a reaction where the same element is both oxidised and reduced?
Disproportionation reaction
What happens to the reducing ability of halide ions down group 7?
It increases
What do sodium halides and sulfuric acid form?
NaHSO4 + HydrogenHalide (e.g. HCl)
What is used to test for halide ions?
Acidified silver nitrate
Why is silver nitrate acidified to test for halide ions?
It is acidified to remove any impurities that might provide a fake positive e.g. carbonates
How can halide ions be tested further after using silver nitrate?
By using dilute ammonia to make the AgCl dissolve then using concentrated ammonia to dissolve the AgBr
AgI will never dissolve and will always be a yellow precipitate
What does chlorine react with cold water to produce?
Cl2 + 2H2O = HCl + HClO
What does sodium hydroxide and Chlorine produce?
NaClO + NaCl + H2O
NaClO is used for bleach
What is chlorine used for in water?
Chlorine is used to purify water supplies because the chloric (I) acid (HClO) is an oxidising agent and kills bacteria by oxidation
