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Edexcel International A Level Chemistry

Mass Spectrometry

Mass spectrometry separates positive ions according to their mass-to-charge ratio, written as m/z. These pages build from the operation of the mass spectrometer through to isotope abundance, relative atomic mass and interpreting molecular spectra.

Exam Unit
Unit 1
WCH11/01 – IAS
Specification Points
2.6 – 2.7
2 points covered
Sub-topics
4 lessons
Revision notes available
Exam Board
Edexcel IAL
Pearson International

Revision Notes

4 revision notes, in the order the specification teaches them.

A mass spectrometer with a stream of ions curving to a detector
1

The Mass Spectrometer

Revise vaporisation, ionisation, acceleration, deflection, detection and why ions are separated by m/z.

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A three-peak isotope spectrum beside a balance
2

RAM Calculations

Use isotopic mass and percentage abundance data to calculate relative atomic mass using weighted means.

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Three diatomic molecules and their three spectrum peaks
3

Predicting Diatomic Mass Spectra

Predict molecular ion peak patterns for diatomic molecules using isotope combinations and probability ratios.

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A molecule fragmenting above a many-peak spectrum
4

Identifying Compounds from Mass Spectra

Use molecular ion peaks and fragment peaks to support compound identification from a mass spectrum.

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Summary Map

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Summary map

Download, print and revise the key facts of this topic at a glance.

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Summary map · PDF

Atoms and Mass Spectrometry Map

Edexcel International A Level Chemistry · Unit 1 · Topic 2A Atoms and Mass Spectrometry

The whole section on one A4 page: sub-atomic particles, isotopes, the mass spectrometer, relative atomic mass and the spectra of molecules.

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8 exam-style multiple-choice papers, MCQ (A) to (H): 155 questions on Topic 2 Atomic Structure and The Periodic Table, written the way the exam asks them.

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2.1

  1. a

    know the structure of an atom in terms of electrons

    Revise
  2. b

    know the structure of an atom in terms of protons

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  3. c

    know the structure of an atom in terms of neutrons

    Revise

2.2

  1. a

    know the relative mass of protons

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  2. b

    know the relative charge of protons

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  3. c

    know the relative mass of neutrons

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  4. d

    know the relative charge of neutrons

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  5. e

    know the relative mass of electrons

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  6. f

    know the relative charge of electrons

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2.3

  1. a

    know what is meant by the term 'atomic (proton) number'

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  2. b

    know what is meant by the term 'mass number'

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2.4

  1. a

    be able to use atomic number and mass number to determine the number of electrons in an atom or ion

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  2. b

    be able to use atomic number and mass number to determine the number of protons in an atom or ion

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  3. c

    be able to use atomic number and mass number to determine the number of neutrons in an atom or ion

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2.5

  1. 2.5

    understand the term ‘isotope’

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2.6

  1. i a

    understand the basic principles of a mass spectrometer

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  2. i b

    be able to analyse and interpret mass spectra to: deduce the isotopic composition of a sample of an element

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  3. ii a

    understand the basic principles of a mass spectrometer

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  4. ii b

    be able to analyse and interpret mass spectra to: calculate the relative atomic mass of an element from relative abundances of isotopes and vice versa

    Revise
  5. iii a

    understand the basic principles of a mass spectrometer

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  6. iii b

    be able to analyse and interpret mass spectra to: determine the relative molecular mass of a molecule, and hence identify molecules in a sample

    Revise
  7. iv a

    understand the basic principles of a mass spectrometer

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  8. iv b

    be able to analyse and interpret mass spectra to: understand that ions in a mass spectrometer may have a 2+ charge

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2.7

  1. a

    be able to predict mass spectra for diatomic molecules, including chlorine, given isotopic abundances

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  2. b

    be able to predict relative peak heights for diatomic molecules, including chlorine, given isotopic abundances

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2.8

  1. a

    be able to define first ionisation energy

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  2. b

    be able to define second ionisation energy

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  3. c

    be able to define third ionisation energy

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  4. d

    understand that all ionisation energies are endothermic

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2.9

  1. 2.9

    know that an orbital is a region within an atom that can hold up to two electrons with opposite spins

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2.10

  1. a

    understand how ionisation energies are influenced by the number of protons in the nucleus

    Revise
  2. b

    understand how ionisation energies are influenced by electron shielding

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  3. c

    understand how ionisation energies are influenced by the sub-shell from which the electron is removed

    Revise

2.11

  1. i

    know that ideas about electronic structure developed from: an understanding that successive ionisation energies provide evidence for the existence of quantum shells and the group to which the element belongs

    Revise
  2. ii

    know that ideas about electronic structure developed from: an understanding that the first ionisation energy of successive elements provides evidence for electron sub-shells

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2.12

  1. a

    be able to describe the shape of an s orbital

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  2. b

    be able to describe the shape of a p orbital

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2.13

  1. i

    know that orbitals in sub-shells: each take a single electron before pairing up

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  2. ii

    know that orbitals in sub-shells: pair up with two electrons of opposite spin

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2.14

  1. a

    be able to predict the electronic configuration of atoms of the elements from hydrogen to krypton inclusive using s, p, d notation

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  2. b

    be able to predict the electronic configuration of ions of the elements from hydrogen to krypton inclusive using s, p, d notation

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  3. c

    be able to predict the electronic configuration of atoms of the elements from hydrogen to krypton inclusive using electron-in-boxes notation

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  4. d

    be able to predict the electronic configuration of ions of the elements from hydrogen to krypton inclusive using electron-in-boxes notation

    Revise

2.15

  1. 2.15

    understand that electronic configuration determines the chemical properties of an element

2.16

  1. a

    know that the Periodic Table is divided into blocks, such as s, p and d

  2. b

    know the number of electrons that can occupy s sub-shells in the first four quantum shells

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  3. c

    know the number of electrons that can occupy p sub-shells in the first four quantum shells

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  4. d

    know the number of electrons that can occupy d sub-shells in the first four quantum shells

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2.17

  1. a

    be able to represent data in graphical form for elements 1 to 36

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  2. b

    be able to use logarithms of first ionisation energies on a graph for elements 1 to 36

  3. c

    be able to explain the meaning of the term 'periodic property'

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2.18

  1. i

    be able to explain: the trends in melting and boiling temperatures of the elements of Periods 2 and 3 of the Periodic Table in terms of the structure of the element and the bonding between its atoms or molecules

    Revise
  2. ii

    be able to explain: the general increase and the specific trends in ionisation energy of the elements across Periods 2 and 3 of the Periodic Table

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  3. iii

    be able to explain: the decrease in first ionisation energy down a group

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