Group 7 Halogens

Matt Storey
Flashcards by Matt Storey, updated more than 1 year ago
Matt Storey
Created by Matt Storey over 7 years ago


A Levels Chemistry Flashcards on Group 7 Halogens, created by Matt Storey on 04/26/2014.

Resource summary

Question Answer
What are the 5 group 7 halogen molecules? Give a description of the first four at room temperature Fluorine (pale yellow gas), chlorine (green gas), bromine (red/brown liquid), iodine (black solid)
What is the trend in atomic radii as we go down group 7? It increases as each new element gains an extra energy level
What is the trend in electronegativity as we descend group 7? It decreases because element gains another energy level which means the outer electrons are further away from the nucleus and there is increased shielding
What is the trend in melting point as you go down group 7? It increases as the atoms have more electron which increases the strength of the van der waals force holding them together
What is the trend in oxidising ability of the group 7 elements as we go down the group? It decreases because the atoms become bigger and increased shielding means they have cannot reduce other elements as easily. Fluorine is the most reducing element.
What happens to the group seven halides in a redox reaction? They gain electrons are reduced meaning they act as good oxidising agents
What is a displacement reaction between halogens? Halogens react in a solution in such a way that a halide in a compound will be displaced by a more reactive halogen
Fluorine will displace bromine in a compound. True of False? fluorine is more reactive than bromine
A halide will always be displaced in a compound by halogen above, or below it in the periodic table? Above as there is a decrease in reactivity down group seven and halide ions are always displaced by halogens which are more reactive then themselves
Halide ions cannot act as reducing agents true or false? False, halide ions can give away electrons to form neutral halogen molecules
What compound do all sodium halides react with? Sulphuric acid (H2SO4)
When sodium chloride reacts with sulphuric acid 1.What is observed? 2.What are the products? 3.What type of reaction occurs? 1.Steamy fumes of hydrogen chloride 2.Solid sodium hydrogen sulfate 3. Acid Base reaction (no change in any oxidation state)
Bromine is a stronger reducing agent than chlorine and fluorine, hydrogen bromide oxidises the oxidation state of sulphur in sulphuric acid from +6 to what? And what products does the sulphur form? From +6 to +4 and forms sulphur dioxide
Hydrogen iodide can oxidise sulphuric acid to three different oxidation states, what are these oxidation states and in what compound does sulphur have these oxidation states? From+6 to +4 forming sulphur dioxide. Then to 0 forming sulphur. The to -2 forming hydrogen sulfate
What is observed when reacting sodium iodide and sulphuric acid? Steamy fumes of hydrogen iodide, black solid iodine formed, solid yellow sulphur and strong egg smell of hydrogen sulphide gas
What forms when metal halides react with silver ions in aqueous solution? Insoluble silver halide precipitate formed
Why does silver fluoride not form a precipitate? It is insoluble in water
Why is dilute nitric acid added to a halide solution before performing a silver test? To remove any hydroxide or carbonate impurities which may interfere with the test by forming insoluble silver carbonate or insoluble silver hydroxide
What are the distinguishing colours of each of the silver halide precipitates? Silver fluoride forms no precipitate. Silver chloride forms a white precipitate, silver bromide forms a cream precipitate and silver iodide forms a yellow precipitate
Since the colours of the silver halides are similar how can we distinguish between them using ammonia? Silver chloride dissolves in dilute ammonia, silver bromide dissolves in concentrated ammonia, silver iodide does not dissolve in concentrated ammonia
What products are formed when chlorine reacts with water in a reversible reaction Chloric(1) acid and hydrochloric acid
What is a disproportionation reaction? A reaction in which the oxidation of some atoms increase and others decrease
What are the properties of chloric (I) acid? Acid, oxidising agent kills bacteria acts as a bleach
What is formed when chlorine reacts with water in the presence of sunlight? Hydrochloric acid is formed meaning chlorine is rapidly lost from pools in the sunlight
How can pools be chlorinated instead of using direct chlorination? Add solid sodium chlorate which in water forms chloric (I) acid however acid is levels are maintained
What forms when chlorine reacts with cold sodium hydroxide? Sodium chloride and sodium chlorate (I) this is another disproportionation reaction
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