22.5.1 Halogens

Question 1

Halogens

Answer 1

• 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.

Question 2

note

Answer 2

• 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.

Question 3

Which halogen is most reactive?

Answer 3

Fluorine

Question 4

What important essential nutrient is found in kelp?

Answer 4

Iodine

Question 5

How are bromine and iodine usually produced?

Answer 5

By treating salt solutions with chlorine

Question 6

How many elements are stronger oxidants than fluorine?

Answer 6

0

Question 7

Which of the following is not a halogen?

Answer 7

Radon

Question 8

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

Answer 8

The electronegativity of fluorine is 4.0.

Question 9

Why does fluorine have a smaller electron affinity than chlorine?

Answer 9

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

Question 10

Teflon is a polymer formed of carbon and what halogen?

Answer 10

Fluorine

Question 11

The halogens all form what type of molecules?

Answer 11

Diatomic

Question 12

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

Answer 12

Valence configuration of ns2np3