Atoms, nuclei and radiation — common mistakes

Always remember the conservation laws for nuclear reactions! Total charge, nucleon number, and lepton number must always balance on both sides of a decay equation. This is a common check for correctness in exam questions.

It disproved the 'plum pudding' model by showing that atoms are mostly empty space, with a tiny, dense, positively charged nucleus at their core. This completely changed our understanding of atomic architecture, forming the basis of our current model.

Alpha particles are relatively heavy and highly ionising but have very low penetrating power (stopped by paper). Gamma rays are high-energy photons with very low ionising ability but extremely high penetrating power (requiring thick lead or concrete to stop).

An antiparticle has the exact same mass as its particle counterpart but possesses the opposite electric charge and other quantum numbers. For example, a positron ($e^+$) is the antiparticle of an electron ($e^-$).

Hadrons are composite particles made of quarks (e.g., protons, neutrons) and they experience the strong nuclear force. Leptons are fundamental particles (e.g., electrons, neutrinos) that do not experience the strong force.