CAIE A-Level Chemistry 11.1 Physical Properties of Group 17

Practise describing halogen colour, physical state and volatility trends and explaining them using molecular forces.

Exam points

recall the colours and physical states of chlorine, bromine and iodine at room conditions
explain decreasing volatility down the group through stronger London forces between larger molecules
explain the general weakening of X–X bonds through longer bonds and reduced orbital overlap

Covered syllabus points

11.1.1—Colours and the trend in volatility 11.1.2—Trend in the bond strength of the halogen 11.1.3—The volatility of the elements

[Maximum number: 3]

The halogens chlorine, bromine and iodine show trends in chemical and physical properties down the group.

Table 3.1 shows some properties of chlorine, bromine and iodine.

Table 3.1

(a)

Complete Table 3.1.

[ 1 ]

(b)

The bond energy values in Table 3.1 refer to the X-X bond where X is the halogen. Explain the trend in the bond strength of the X-X bond in the halogens.

[ 2 ]

[Maximum number: 2]

The Group 17 elements are oxidising agents.

$\mathrm{Cl}_{2}$ and $\mathrm{Br}_{2}$ can each react with $\mathrm{NH}_{3}$ to give $\mathrm{N}_{2}$ and a hydrogen halide, HX .

3 \mathrm{X}_{2}+2 \mathrm{NH}_{3} \rightarrow \mathrm{~N}_{2}+6 \mathrm{HX}

X = Cl or Br

The relative bond strengths of X-X and H-X determine the difference in enthalpy change of the two reactions.

Describe and explain the difference in the X-X bond strengths of $\mathrm{Cl}_{2}$ and $\mathrm{Br}_{2}$ .

[Maximum number: 3]

The halogens chlorine, bromine and iodine are all volatile elements.

State and explain the trend in volatility down Group 17.

All question bank results loaded

Covered syllabus points

11.1 Physical properties of the Group 17 elements question 1

Question (a)

Question (b)

11.1 Physical properties of the Group 17 elements question 2

11.1 Physical properties of the Group 17 elements question 3