Virtual Lessons

Topic 1 Atomic Structure and The Periodic Table, taught by a specialist chemistry teacher.

This lesson comes with the full course

The Virtual Lessons come with the Topic 1 Atomic Structure and The Periodic Table course, with every MCQ and exam practice paper, marked by a specialist chemistry teacher. Already bought it? Log in.

Lesson 1 of 5

Atom & Mass Spectrometry

This virtual lesson covers the structure of the atom, the nature of isotopes, and how mass spectrometry is used to analyse the composition and mass of atoms and molecules.

The lesson opens with the structure of the atom in terms of electrons, protons, and neutrons, including their relative masses and charges. The terms atomic (proton) number and mass number are defined and used to determine the number of each subatomic particle in any atom or ion. The concept of isotopes is introduced, explaining how atoms of the same element can differ in their number of neutrons.

The lesson then covers the basic principles of a mass spectrometer and how to analyse and interpret mass spectra. This includes deducing the isotopic composition of an element from its spectrum, calculating relative atomic mass from isotopic abundances and vice versa, and determining the relative molecular mass of a molecule to identify unknown substances in a sample. The significance of ions carrying a 2+ charge in the mass spectrometer, and the effect this has on the m/z ratio, is also explained.

The lesson concludes by working through the prediction of mass spectra for diatomic molecules such as chlorine, including how the relative peak heights arise from different isotope combinations and their natural abundances. This lesson establishes the quantitative and analytical foundations central to much of A-Level Chemistry.

Next: Atomic Orbitals and Electronic Configuration

Specification points for Topic 1

1know the structure of an atom in terms of electrons, protons and neutrons
2know the relative mass and relative charge of protons, neutrons and electrons
3know what is meant by the terms atomic (proton) number and mass number
4be able to determine the number of each type of sub-atomic particle in an atom, molecule or ion from the atomic (proton) number and mass number
5understand the term isotopes
6be able to define the terms relative isotopic mass and relative atomic mass, based on the ¹²C scale
7understand the terms relative molecular mass and relative formula mass, including calculating these values from relative atomic masses. The term relative formula mass should be used for compounds with giant structures.
8be able to analyse and interpret data from mass spectrometry to calculate relative atomic mass from relative abundance of isotopes and vice versa
9be able to predict the mass spectra, including relative peak heights, for diatomic molecules, including chlorine
10understand how mass spectrometry can be used to determine the relative molecular mass of a molecule. Limited to the m/z value for the molecular ion, M⁺, giving the relative molecular mass of the molecule.
15understand how ideas about electronic configuration developed from:
16know the number of electrons that can fill the first four quantum shells
17know that an orbital is a region within an atom that can hold up to two electrons with opposite spins
18know the shape of an s-orbital and a p-orbital
19know the number of electrons that occupy s, p and d sub-shells
20know that electrons fill sub-shells singly, before pairing up, and that two electrons in the same orbital must have opposite spins
21be able to predict the electronic configurations, using 1s notation and electrons-in-boxes notation, of:
22know that elements can be classified as s, p and d-block elements
23understand that electronic configuration determines the chemical properties of an element
11be able to define the terms first ionisation energy and successive ionisation energies
12understand how ionisation energies are influenced by the number of protons, the electron shielding and the electron sub-shell from which the electron is removed
13understand reasons for the general increase in first ionisation energy across a period
14understand reasons for the decrease in first ionisation energy down a group
24understand periodicity in terms of a repeating pattern across different periods
25understand reasons for the trends in the following properties of the elements from periods 2 and 3 of the Periodic Table:
26be able to illustrate periodicity using data, including electronic configurations, atomic radii, melting and boiling temperatures and first ionisation energies

Atom & Mass Spectrometry

Keep this note — free