Group 7 Flashcards
(19 cards)
What are the physical properties of the halogens
They get darker and denser going down the group (from a liquid to a solid),
They all smell like a swimming pool,
What is the electronegativity trend
It decreases going down the group
What is the MP/BP trend
It increases going down the group
Why does the electronegativity decrease
Because the shared/outer electron pair in further away from the nucleus (electron shielding)
Why does the MP/BP increase
Larger atoms have more electrons so the van der Waals forces are much stronger
What is the trend in oxidising ability
It decreases going down the group
How do Halogens react normally
They usually become negative ions by gaining an electron and so have a charge of -1
What is a Halide
A halogen ion
How do halogens react with metal halies
Halides in a compound can be displaced by a more reactive halogen
Are halides reducing or oxidising agents
Reducing agents
What happens to the halide ions when they act as reducing agents
They lose electrons and become halogen molecules
What is the trend in reducing power in halide ions
In increases going down the group because larger ions can loose an electron more easily
How does sodium chloride react with concentrated sulfuric acid
Hydrogen chloride fumes and sodium hydrogensulfate solid is produced,
It is not a redox reaction,
It is an acid-base reaction
How does sodium bromide react with concentrated sulfuric acid
Fumes of hydrogen bromide and brown fumes of bromine, sulfur dioxide is also formed
Bromide ions are strong enough to reduce sulfuric acid to sulfur dioxide so it is a redox reaction
How does sodium iodide react with concentrated sulfuric acid
Fumes of hydrogen iodide and a black solid of iodine,
Yellow solid sulfur may be seen as well as colourless sulfur dioxide,
Redox reaction- can reduce sulfuric acid even more than bromide ions
What does chlorine and water make
Chloric acid and hydrochloric acid
What is disproportionation
The oxidation state of some of the atoms of an element increase while others of the same atom decrease,
This happens in the reaction with chlorine and water
How is chlorine used to purify water
Chloric acid is an oxidising agent so kills bacteria by oxidation- it is also a bleach
What does chlorine and dilute sodium hydroxide form
Sodium chlorate which is an oxidising agent and the active ingredient in bleach (also a disproportionation reaction)
