Atomic Structure (Edexcel A Level Chemistry): Exam Questions

This question is about chlorine.

Chlorine has two isotopes with mass numbers 35 and 37.

i) Complete the table to show the numbers of subatomic particles in a ³⁵Cl atom and a ³⁷Cl⁻ ion.

(2)

ii) A sample of chlorine contained 75% of ³⁵Cl and 25% of ³⁷Cl.

Complete the mass spectrum to show the peaks you would expect for the molecular ion  from this sample of chlorine gas.

(2)

Write the formula of potassium chlorate(V).

Write the equation for the first electron affinity of chlorine. Include state symbols.

The standard electrode potential for the chlorine / chloride ion half-cell is

1⁄2Cl₂ (aq) + e⁻ ⇌ Cl⁻ (aq)    = +1.36 V

i) Identify an oxidising agent from the Data Booklet that will convert chloride ions into chlorine under standard conditions.

(1)

ii) Calculate the value of  for the reaction in (d)(i).

(1)

This question is about atoms, molecules and ions.

Lithium exists as two isotopes.

Complete the table to show the numbers of subatomic particles in a ⁶Li atom and a ⁷Li⁺ ion.

The mass spectrum of a diatomic molecule, X₂, has peaks at the following m / z values for the X₂⁺ ion:

32, 33, 34, 35, 36

Deduce the formulae of all the species responsible for each of the peaks in the mass spectrum of X₂, identifying element X and showing clearly the isotopes present.

Complete the table to show the maximum number of electrons which can fill each region of an atom.

This question is about isotopes.

State, in terms of subatomic particles, what is meant by the term isotopes.

The element gallium has a relative atomic mass of 69.735 and only contains two isotopes.

A sample of gallium contained the isotope ⁶⁹Ga, with a relative abundance of 63.25 %.

Calculate the mass number of the other isotope. You must show all your working.

This question is about isotopes.

The table shows data for some isotopes of potassium.

i) State what is meant by the terms ‘relative isotopic mass’ and ‘relative atomic mass’.

(3)

ii) State what is meant by the term ‘isotopes’. Illustrate your answer by referring to the isotopes of potassium.

(2)

iii) Use the data in the table to calculate the relative atomic mass of potassium.

Give your answer to 4 significant figures.

(2)

The relative isotopic abundances of an element can be measured using a mass spectrometer.
A simplified and incompletely labelled diagram of a mass spectrometer is shown.

i) Name the feature of the mass spectrometer responsible for the behaviour of the ions in the region indicated by the arrow X.

(1)

ii) Explain the three ion pathways, A, B and C, shown in the region indicated by the arrow X.

(3)

iii) Give a reason why the mass spectrometer must be operated under vacuum.

(1)