ES.1 Flashcards
Chemistry of the halogens
What are halogens?
Halogens are elements from group 7 of the periodic table.
What are two ways halogen atoms can achieve its stability by?
- Gain an electron from a metal atom to form a hallide ion in an ionic compound.
- Share an electron with a non-metal atom to form a covalently bonded compound. (They also form diatomic molecules with another atom of the same element.)
Describe the appearances of the first four halogens at room temperature.
Fluorine: pale yellow gas.
Chlorine: green gas.
Bromine: dark red volatile liquid.
Iodine: shiny grey solid, sumblimes to give purple vapour when heated.
List trends of properties as you go down the group. (3p)
- Higher melting and boiling points (bigger id-id intermolecular forces).
- Less volatile.
- Less reactive.
What can you say about the solubility of halogens? (3p)
- Halogens are generally not very soluble in water.
- Fluorine reacts with water.
- Halogens are generally quite soluble in organic solvents.
What is halogens often refer to as in a redox reaction?
The oxidising agent.
What is it called when an atom loses an electron?
We say it is oxidised.
What is it called when an atom gains an electron?
We say it is reduced.
What are the ions called that are left out of the ionic equation of a reaction because they are unchanged?
Spectator ions.
What is it meant by a displacement reaction?
This is when a halogen displaces a less reactive halogen from a compound.
What is it meant by a redox reaction?
This is when both oxidation and reduction have occurred in the same reaction.
What are three things you can say to summarise the reaction of halogens and hallide ions?
- Reactivity decreases down the group.
- The strongest oxidising agent is fluorine.
- A halogen displaces a less reactive halogen.
How can you make it easier to distinguish the difference between the silver hallide percipitates instead of just looking at colours?
Add ammonia solution and look at the solubility of the percipitates. Silver chloride is most soluble in ammonia.
Silver chloride > silver bromide > silver iodide