Group 7, The Halogens 3.2.3 Flashcards
What is the colour and state of these Group 7 elements
Fluorine
Chlorine
Bromine
Iodine
Fluorine - pale yellow gas
Chlorine - green gas
Bromine - red brown liquid
Iodine - grey solid
When iodine sublimes, what colour vapour does it form
Purple
Explain the trend in meting and boiling points going down Group 7, halogens
Melting and boiling points increases
Atomic size increases
More electrons and larger surface area
Stronger van der waals forces
More energy needed to overcome these forces
What charge ions do halogens form and why
-1 as they gain electrons
Explain the trend in oxidising ability going down Group 7, halogens
Decreases
Number of shells increases
More sheilding
Weaker attraction of electrons to the nucleus
Harder to gain electrons
What type of moelucles do halogens exist as
Diatomic moelcules
Describe the overall reactivity of Group 7 non metals
Very reactive non metals
During displacement reactions between halogens and halide ions in aqueous solutions, what colour is the solution when Bromine and Iodine is formed
Bromine - Orange solution
Iodine - brown solution
Why is chlorine added to water
It produces chloric acid which kills bacteria by oxidation
Why is chlorine allowed to be used in swimming pools
Only a small amount of chlorine used which is toxic
Health benefits outweigh the risks
What is special about using chlorine in swimming pools that are exposed to sunlight
Chlorine is rapidly lost from pool water in sunlight
Chlorine must be added regularly to shallow pools in summer
What is an alternative fo direct chlorination of swimming pools and how does this work
Add solid sodium/calcium chlorate
It dissolves in water to form chloric acid
When chlorine Reacts with alkali, what conditions are needed for the alkali
The alkali has to be cold and dilute
What can sodium chlorate be used as
Oxidising agent and is the active ingredients in domestic bleach
Explain the trend in reducing ability of halide ions going down the group
Increases reducing ability
Atomic size increases
More shielding
Outer electron is less strongly held by the nucleus and can mote easily be lost
In what reaction can the trend in reducing ability of halogens be seen
Sodium sodium halide with concentrated sulfuric acid
In what reaction can the trend in oxidising ability of halogens be seen
Displacement reaction between halogens and halide ions in aqueous solutions
When reacting solidum sodium chloride with concentrated sulfuric acid, what are the observations
White steamy fumed of Hydrochloric gas
Halogens Samsung notes
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Tests SAMSUNG NOTES
First mocksss
What reagents are needed for testing halides
Nitric acid and silver nitrate solution
When testing for halides, what observations are made for the presence of chloride,bromide and iodide ions
Chloride ions - white precipitate
Bromide ions - Cream precipitate
Iodide ions - Yelloe precipitate
Why is nitric acid used when testing for halides
To remove ions that interference with the test
Why can’t HCL be used when testing for halides
Forms a white precipitate of AgCl, which would invalidate the test and give a false positive
Why can’t fluoride ions be used when testing for halides
Silver fluoride is soluble and doesn’t form a precipitate
Explain the further tests for confirmation of testing for halides
Silver chloride - white ppt - dissolved in dilute ammonia
Silver bromide - cream ppt - dissolves in concentrated ammonia
Silver iodide - yellow ppt - Insoluble in concentrated ammonia
