Halogens

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  • Created by: jodi
  • Created on: 09-01-19 16:31
Why do the first ionisation energies of the halogens decrease going down the group?
The outer electrons are increasingly further from the nucleus; Outer electrons are shielded by inner electrons and the effect of the nuclear charge is reduced; as a result, the ability of the nucleus to hold electrons is reduced.
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Why do the bond energies decrease of the halogens going down the group?
The atomic radii of the elements increase leading to increased bond lengths between atoms in a molecule and decreased bond energies.
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What is the order of bond energies of the halogens?
F-F < Cl-Cl > Br-Br > I-I
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Why is the F-F bond weak?
The small size of fluorine brings the lone pairs of electrons in F-F closer together creating repulsion.
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Why does the solubility of the halogens decrease going down the group?
Chlorine and bromine are only slightly soluble; iodine is virtually insoluble. Halogens are non-polar with weak VDWs whereas water is polar with strong hydrogen bonds. (Like dissolves like)
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What colour is iodine in ethanol?
Yellow/brown
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What is the equation when chlorine reacts with water?
Cl (g) + H O (l) --> HOCl (aq) + HCl (aq)
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What type of reaction is chlorine with water?
Disproportionation.
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What is HOCl?
Hypochlorous acid.
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What is the equation for the reaction between chlorine and cold dilute sodium hydroxide?
2NaOH + Cl --> NaCl + NaClO + H O
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What is the ionic equation for the reaction between chlorine and cold dilute sodium hydroxide?
2OH + Cl --> Cl + ClO + H O
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What is NaClO?
Sodium chlorate (I)
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What is the equation for the reaction between chlorine and hot concentrated sodium hydroxide solution?
3Cl + 6NaOH --> 5NaCl + NaClO + 3H O
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What is NaClO ?
Sodium chlorate (v)
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Does iodine react with cold dilute sodium hydroxide?
No; it only reactions with hot concentrated sodium hydroxide solution.
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Why does the oxidising power of the halogens decrease going down the group? (use fluorine as an example)
Oxidising agents readily accept electrons; The elctron gained by fluorine completes an energy level closer to its nucleus in comparison to other halogens. This has a stronger attraction to the nucleus because of the shorter distanc; less shielding
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What is an oxidising agent?
They cause oxidation to occur so they cause another atom to lose electrons. This means that the oxidising agent gains electrons and becomes reduced.
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Other cards in this set

Card 2

Front

Why do the bond energies decrease of the halogens going down the group?

Back

The atomic radii of the elements increase leading to increased bond lengths between atoms in a molecule and decreased bond energies.

Card 3

Front

What is the order of bond energies of the halogens?

Back

Preview of the front of card 3

Card 4

Front

Why is the F-F bond weak?

Back

Preview of the front of card 4

Card 5

Front

Why does the solubility of the halogens decrease going down the group?

Back

Preview of the front of card 5
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