In A-level Chemistry, the atomic structure section of physical chemistry usually covers a common core across exam boards, with small differences in emphasis. Students learn how atoms are built, how electron arrangements explain chemical behaviour, and how evidence such as mass spectra, ionisation energies, and sometimes emission spectra supports atomic models.
Students are expected to know the structure of the atom in terms of protons, neutrons, and electrons, including their relative charges and relative masses. They also use atomic number and mass number to determine the numbers of particles in atoms and ions.
This includes understanding what isotopes are and how they differ in neutron number. Students also learn to define and use terms such as relative isotopic mass, relative atomic mass, and in some exam boards, relative molecular mass and relative formula mass.
Mass spectrometry is a standard part of the atomic structure topic. Students typically need to understand the principles of the technique and interpret simple mass spectra to identify isotopes, calculate relative atomic mass, and sometimes determine relative molecular mass.
Students learn to write electron configurations for atoms and ions, commonly up to atomic number 36. This includes the arrangement of electrons in shells and sub-shells, and how these arrangements relate to chemical properties.
Some specifications explicitly include the idea of an orbital as a region that can hold up to two electrons with opposite spins. Students may also be expected to know the shapes of s- and p-orbitals, the capacities of sub-shells, and the rules governing the filling of orbitals.
This is a major analytical part of the topic. Students define first ionisation energy and sometimes successive ionisation energies. They explain trends using ideas such as nuclear charge, distance from the nucleus, shielding, and sub-shell structure.
Some exam boards also include atomic emission spectra as evidence for quantum shells.
In more detailed specifications, students may study the hydrogen emission spectrum and relationships such as
E = hf and f = c / λ.
If your teacher says atomic structure in A-level physical chemistry, the main sequence to remember is:
particles → isotopes → mass spectrometry → electron configuration → orbitals → ionisation energies → spectra/evidence for shells