Group 7
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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What sort of molecules do Halogens exist in as an element?
Diatomic Molecules. Two covalently bonded.
What are the physical properties of Halogens?
• Low melting and boiling points - Exist as diatomic molecules
What is the trend in Boiling point in the Halogens?
As you move down the group the Boiling point increases.
What causes the trend in the Halogen’s boiling points?
As you go down it increases as there are more electrons. There are more Van Der Waals forces.
What is an Oxidising Agent?
An element that oxidises other elements in a redox reaction.
What happens to Halogens in terms of electrons in a Redox reaction?
They gain an electron to form a halide ion with a negative one charge.
What is the trend in oxidising power for the Halogens?
As you head down they become less strong oxidising agents.
What is the trend in Reactivity for Halogens?
As you head down they become less reactive.
What causes the trend in Reactivity/Oxidising power for the Halogens?
• The atomic Radius Increases • The electron shielding increases • This cancels out a higher atomic charge • So the ability to gain an electron decreases
What tests can be done to show the Reactivity of the halogens?
Displacement between Halide Ions and the Halogens in Aqueous solution .
What organic solvent can be used to show a displacement reaction has taken place?
Cyclohexane.
What colour is Cl2 in Water?
Pale-green
What colour is Br2 in Water?
Orange
What colour is I2 in Water?
Brown
What colour is Cl2 in Cyclohexane?
Pale-green
What colour is Br2 in Cyclohexane?
Orange
What colour is I2 in Cyclohexane?
Violet
In a displacement reaction what happens to the stronger oxidising agent?
It forms ions. It becomes part of the compound.
Define a Displacement reaction.
A displacement reaction is a reaction where a more-reactive/stronger oxidising agent displaces a less-reactive/ weaker oxidising agent from an aqueous solution of the latters ions.
Define a disproportionation reaction.
Where an element is both Oxidised and Reduced in a redox reaction.
What is a reaction where the same element is both Oxidised and Reduced?
Disproportionation.
Why is Chlorine added to water?
Because it kills bacteria.
What is the danger of adding Chlorine to water?
It can form toxic chlorinated hydrocarbons.
What are the products of Chlorine and Water?
Two acids: • HCl-Hydrochloric Acid • HClO-Chloric (I) Acid