Group 17 Halogens Properties and Reactions

These flashcards cover the physical and chemical properties of Group 17 elements (halogens), their reactions, environmental significance, and the importance of chlorine in various applications.

What are the physical states and colors of the Group 17 elements at room temperature?

Fluorine - pale yellow gas; Chlorine - green gas; Bromine - red-brown liquid; Iodine - grey solid.

What trend is observed in the boiling points of halogens as you go down Group 17?

Boiling points increase due to the increasing strength of intermolecular forces.

Which halogen is the most volatile and why?

Fluorine is the most volatile because it has the lowest melting and boiling points due to the weakest van der Waals forces.

What happens to the reactivity of halogens down Group 17?

Reactivity decreases down the group because it becomes harder to gain an electron due to increased electron shielding and atomic radius.

What is the strongest oxidising agent among the halogens?

Chlorine is the strongest oxidising agent.

Write the displacement reaction equation for chlorine and bromide ions.

Cl2 + 2Br- → 2Cl- + Br2.

What type of reaction occurs when halogens react with hydrogen?

They form hydrogen halides, and reactivity decreases down Group 17.

What is the standard reaction equation for hydrogen halide formation?

X2 + H2 → 2HX, where X is the halogen.

How does thermal stability of hydrogen halides change down Group 17?

Thermal stability decreases down Group 17 because the covalent bonds weaken.

What happens when silver nitrate is used to test for halide ions?

A precipitate forms: fluoride - no precipitate, chloride - white, bromide - cream, iodide - yellow.

Describe the reaction of sodium chloride with concentrated sulfuric acid. What is produced?

NaCl + H2SO4 → NaHSO4 + HCl; misty fumes of HCl are produced.

What is the result of the reaction between sodium bromide and concentrated sulfuric acid?

NaBr + H2SO4 → NaHSO4 + HBr; produces misty fumes of HBr and can further react to produce SO2 and Br2.

What is a disproportionation reaction?

A reaction in which an element is both oxidised and reduced.

How does chlorine react with dilute sodium hydroxide?

Chlorine reacts with cold dilute sodium hydroxide to form NaCl and NaClO, which is a disproportionation reaction.

What is the environmental significance of chlorine in water purification?

Chlorine kills bacteria and helps prevent diseases in drinking water.

What compounds are formed from the reaction of chlorine with organic matter, and why is it a concern?

Chlorine can form potentially cancer-causing compounds when reacting with organic matter in water.

What is the impact of CFCs on the ozone layer?

CFCs release chlorine radicals that break down ozone, creating holes in the protective ozone layer.

How is ozone formed in the atmosphere?

Ozone is formed when an oxygen molecule reacts with an oxygen free radical in the presence of UV light.