Atomic Structure & the Periodic Table is a core part of GCSE Chemistry. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
AtomSmallest part of an element; radius about 0.1 nm
NucleusCentre of atom containing protons and neutrons
ProtonPositive particle; relative mass 1, charge +1
NeutronNeutral particle in nucleus; relative mass 1
ElectronNegative particle in shells; mass nearly zero
IsotopeSame protons, different number of neutrons
Relative atomic massAverage mass of isotopes weighted by abundance
Electron configurationArrangement of electrons in shells, e.g. 2,8,1
AbundancePercentage of each isotope in a sample
Shell capacityShells hold 2, 8, 8 electrons at GCSE
Group numberEquals electrons in the outer shell
Period numberEquals number of occupied shells
Plum pudding modelThomson 1904: electrons in positive dough
Questions where students often pick the tempting wrong answer — make sure you know the right one:
Where is almost all the mass of an atom located?✗ Electrons contribute significantly to the mass of an atom.✓ In the nucleus, made up of protons and neutrons.
What is different between two isotopes of the same element?✗ Isotopes have different numbers of electrons, which is why their mass differs.✓ They have the same number of protons but different numbers of neutrons.
Rutherford's gold foil experiment showed atoms have:✗ a uniform positive charge✓ a small dense nucleus
What did the alpha-scattering experiment show?✗ Electrons orbit in shells✓ The atom has a tiny dense positive nucleus
Practise Atomic Structure & the Periodic Table — free games
Test yourself with these quick revision games for this topic:
