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Edexcel International A Level Chemistry

Topic 2
Atomic Structure
& The Periodic Table

Topic 2 builds the foundation for atomic structure, isotopes, mass spectrometry, the quantum model, electronic configuration, ionisation energy and periodic trends. These ideas explain how evidence from spectra and ionisation energies supports modern models of electronic structure.

Exam Unit
Unit 1
WCH11/01 – IAS
Specification Points
2.1 – 2.18
18 points covered
Topic Parts
4 parts
Revision notes available
Exam Board
Edexcel IAL
Pearson International

Revision Notes

Atoms and isotopes
Atomic
Structure
protons, neutrons, electrons and isotopes
1
Available

Atomic Structure

Subatomic particles, relative mass and charge, atomic number, mass number, isotopes and particle calculations.

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Spectra and abundance
Mass
Spectrometry
isotopic composition, RAM, RMM and molecular ions
2
Available

Mass Spectrometry

Principles of a mass spectrometer, interpreting spectra, isotope abundance, relative atomic mass and diatomic mass spectra.

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Orbitals and subshells
Quantum
Model
s and p orbitals, subshells and configurations
3
Available

Quantum Model

Orbitals, quantum shells, sub-shells, orbital box notation, electronic configuration and periodic blocks.

Start revising
Energy and trends
Ionisation
Energy
successive values, shielding and periodic trends
4
Available

Ionisation Energy

First, second and third ionisation energies, successive ionisation energies, periodic trends and evidence for electronic structure.

Start revising
Specification Coverage

Topic 2 Atomic Structure and the Periodic Table – Edexcel International A Level Chemistry

The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 2.

Atomic Structure

2.1
know the structure of an atom in terms of electrons, protons and neutrons
2.2
know the relative mass and charge of protons, neutrons and electrons
2.3
know what is meant by the terms atomic, proton, number and mass number
2.4
be able to use the atomic number and the mass number to determine the number of each type of subatomic particle in an atom or ion
2.5
understand the term isotope

Mass Spectrometry

2.6
understand the basic principles of a mass spectrometer and be able to analyse and interpret mass spectra to:
i
deduce the isotopic composition of a sample of an element
ii
calculate the relative atomic mass of an element from relative abundances of isotopes and vice versa
iii
determine the relative molecular mass of a molecule, and hence identify molecules in a sample
iv
understand that ions in a mass spectrometer may have a 2+ charge
2.7
be able to predict mass spectra, including relative peak heights, for diatomic molecules, including chlorine, given the isotopic abundances

Quantum Model and Electronic Configuration

2.9
know that an orbital is a region within an atom that can hold up to two electrons with opposite spins
2.11
know that ideas about electronic structure developed from:
i
an understanding that successive ionisation energies provide evidence for the existence of quantum shells and the group to which the element belongs
ii
an understanding that the first ionisation energy of successive elements provides evidence for electron sub-shells
2.12
be able to describe the shapes of s and p orbitals
2.13
know that orbitals in sub-shells:
i
each take a single electron before pairing up
ii
pair up with two electrons of opposite spin
2.14
be able to predict the electronic configuration of atoms of the elements from hydrogen to krypton inclusive and their ions, using s, p, d notation and electron-in-boxes notation
2.15
understand that electronic configuration determines the chemical properties of an element
2.16
know that the Periodic Table is divided into blocks, such as s, p and d, and know the number of electrons that can occupy s, p and d sub-shells in the first four quantum shells

Ionisation Energy and Periodic Trends

2.8
be able to define first, second and third ionisation energies and understand that all ionisation energies are endothermic
2.10
understand how ionisation energies are influenced by the number of protons in the nucleus, the electron shielding and the sub-shell from which the electron is removed
2.17
be able to represent data, in a graphical form, including the use of logarithms of first ionisation energies on a graph, for elements 1 to 36 and hence explain the meaning of the term periodic property
2.18
be able to explain:
i
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
ii
the general increase and the specific trends in ionisation energy of the elements across Periods 2 and 3 of the Periodic Table
iii
the decrease in first ionisation energy down a group