1.1 Atomic structure

The chemical properties of elements depend on their atomic structure and in particular on the arrangement of electrons around the nucleus. The arrangement of electrons in orbitals is linked to the way in which elements are organised in the Periodic Table. Chemists can measure the mass of atoms and molecules to a high degree of accuracy in a mass spectrometer. The principles of operation of a modern mass spectrometer are studied.

  • Fundamental particles - An atom consists of a nucleus containing protons and neutrons surrounded by electrons. Appreciate that knowledge and understanding of atomic structure has evolved over time.Early models of atomic structure predicted that atoms and ions with noble gas electron arrangements should be stable:  there are various models to illustrate atomic structure Protons, neutrons and electrons: relative charge and relative mass.  
  • Mass number and isotopes - Definition of mass number (A) and atomic (proton) number (Z). Explain the existence of isotopes Mass spectrometer The principles of a simple time of flight (TOF) mass spectrometer, limited to electrospray ionisation, acceleration to give all ions constant kinetic energy, ion deflection, ion detection, data analysis. The mass spectrometer gives accurate information about relative isotopic mass and also about the relative abundance of isotopes.
  • Electron configuration - Electron configurations of atoms and ions up to Z = 36 in terms of shells and sub-shells (orbitals) s, p and d. Define ionisation energy and definition first ionisation energy Equations for first and successive ionisation energies Explain first ionisation energy trends Explain how first and successive ionisation energies in Period 3 (Na–Ar) and in Group 2 (Be–Ba) give evidence for electron configuration in