22.5.1 Halogens Flashcards Preview

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Flashcards in 22.5.1 Halogens Deck (12)
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1
Q

Halogens

A
  • As a group, the halogens are electronegative; they have high ionization energies and high electron affinities.
  • Diatomic halogens are prepared from the naturally occurring salts and are used in various applications.
2
Q

note

A
  • As a group, the halogens are electronegative; they have high ionizing energies and high electron affinities.
  • Fluorine (F 2 ) is a very strong oxidant but it also has a very low bond enthalpy because it is a small atom. As a result, diatomic fluorine is not as stable as diatomic chlorine and is used less in industry for this reason.
  • Diatomic halogens are prepared from the naturally occurring salts and are used in various applications.
  • The diatomic forms of the halogens do not exist in nature. Chlorine gas is formed in the chlor-alkali process. This electrolytic reaction produces chlorine gas (Cl 2 ), hydrogen gas (H 2 ) and sodium hydroxide (NaOH), all useful compounds.
  • Diatomic bromine and iodine are produced through oxidation of solutions of their salts with chlorine gas. Bromide is a relatively common ion in sea water. Iodine is concentrated by the brown algae known as kelp and so this is used as a source.
  • Fluorine is the strongest oxidant of the group and is produced by electrolysis of molten potassium hydrogen fluoride (KHF 2 ).
  • The halogens have many important uses.
  • The freons or chlorofluorocarbons are used less today because of they damage the ozone layer.
  • Chlorine is important in the sterilization of water and the production of polyvinyl chloride plastics.
  • Silver bromides are important photographic salts.
  • Iodine is an essential element for the human body that is rare in nature. For this reason it is now routinely added to table salt.
3
Q

Which halogen is most reactive?

A

Fluorine

4
Q

What important essential nutrient is found in kelp?

A

Iodine

5
Q

How are bromine and iodine usually produced?

A

By treating salt solutions with chlorine

6
Q

How many elements are stronger oxidants than fluorine?

A

0

7
Q

Which of the following is not a halogen?

A

Radon

8
Q

All the halogens except for fluorine have positive oxidation states, while fluorine has no known positive oxidation states. Why is fluorine different?

A

The electronegativity of fluorine is 4.0.

9
Q

Why does fluorine have a smaller electron affinity than chlorine?

A

In fluorine, there is repulsion between the lone pairs of electrons

10
Q

Teflon is a polymer formed of carbon and what halogen?

A

Fluorine

11
Q

The halogens all form what type of molecules?

A

Diatomic

12
Q

Which of the following is not a property of the halogens?

A

Valence configuration of ns2np3

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