Edexcel IAL Chemistry Topic 2 Checklist

(2025–2026 Exams)

Interactive Checklist

Topic 2: Atomic Structure and the Periodic Table

Atomic Structure

Know the structure of an atom in terms of electrons , protons and neutrons
Know the relative mass and charge of protons, neutrons and electrons
Know what is meant by the terms ‘ atomic (proton) number ’ and ‘ mass number
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
Understand the term ‘ isotope

Mass Spectrometry

Understand the basic principles of a mass spectrometer and be able to analyse and interpret mass spectra to:
– Deduce the isotopic composition of a sample of an element
– Calculate the relative atomic mass of an element from relative abundances of isotopes and vice versa
– Determine the relative molecular mass of a molecule, and hence identify molecules in a sample
– Understand that ions in a mass spectrometer may have a 2+ charge
Be able to predict mass spectra , including relative peak heights, for diatomic molecules, including chlorine, given the isotopic abundances

Ionisation Energies and Electronic Structure

Be able to define first, second and third ionisation energies and understand that all ionisation energies are endothermic
Know that an orbital is a region within an atom that can hold up to two electrons with opposite spins
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
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
– An understanding that the first ionisation energy of successive elements provides evidence for electron sub-shells
Be able to describe the shapes of s and p orbitals
Know that orbitals in sub-shells:
– Each take a single electron before pairing up
– Pair up with two electrons of opposite spin
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
Understand that electronic configuration determines the chemical properties of an element
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

Trends and Periodicity

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
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
– The general increase and the specific trends in ionisation energy of the elements across Periods 2 and 3 of the Periodic Table
– The decrease in first ionisation energy down a group