AP | A-Level | IB | NCERT 11 + 12 – FREE NOTES, RESOURCES AND VIDEOS!
CIE® A-Level
YouTube Channel
YouTube Channel
@chemistry.student
*Revision Materials* 1 Atomic Structure 2 Atoms, molecules and stoichiometry 3 Chemical Bonding 4 States of matter 5 Chemical energetics 6 Electrochemistry 7 Equilibria 8 Reaction kinetics 9 The Periodic Table, chemical periodicity 10 Group 2 11 Group 17 12 Nitrogen and sulfur 13 Organic 14 Hydrocarbons 15 Halogen compounds 16 Hydroxy compounds 17 Carbonyl compounds 18 Carboxylic acids and derivatives 19 Nitrogen compounds 20 Polymerisation 21 Organic synthesis 22 Analytical techniques 23 Chemical energetics 24 Electrochemistry 25 Equilibria 26 Reaction kinetics 27 Group 2 28 Chemistry of transition elements 29 Organic 30 Hydrocarbons 31 Halogen compounds 32 Hydroxy compounds 33 Carboxylic acids and derivatives 34 Nitrogen compounds 35 Polymerisation 36 Organic synthesis 37 Analytical techniques

1 Atomic Structure

1.1 Particles in the Atom and Atomic Radius 1.2 Isotopes 1.3 Electrons, energy levels and atomic orbitals 1.4 Ionisation energy

Isotopes

Specification Reference Physical Chemistry, Atomic Structure 1.2

Quick Notes

  • Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
  • Notation: Isotopes are shown as nZX or X-A, where:
    • Z = atomic (proton) number
    • A = mass (nucleon) number
  • Chemical properties are the same for all isotopes of an element (same electron configuration).
  • Physical properties (e.g. mass, density) differ between isotopes due to different numbers of neutrons.

Full Notes

What Is an Isotope?

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means they have the same atomic number but different mass numbers.

For Example:Carbon has naturally occurring isotopes:

CIE A-Level Chemistry diagram showing carbon-12 and carbon-13 isotopes with 6 protons and differing neutrons.

All are carbon because they have 6 protons.

Isotope Notation

Isotopes are represented using nuclear notation: nZX or X-A

Examples:

Chemical Properties of Isotopes

All isotopes of the same element have the same chemical properties. This is because chemical reactions involve electrons, and isotopes have the same number of electrons and the same electron configuration.

Physical Properties of Isotopes

Isotopes have different physical properties, such as mass and density. This is due to the different number of neutrons, which affects the atom’s total mass.

Summary