5-Bullet Rapid Revision: Atoms & Nuclei

• Bohr model: r_n = 0.529$n^{2}$/Z Å; E_n = −13.6$Z^{2}$/$n^{2}$ eV; KE = −E (positive); PE = 2E (negative). Ground state H: −13.6 eV.

• Spectral series: Lyman = UV (n_{1}=1); Balmer = Visible (n_{1}=2, 656.3–364.6 nm); Paschen = IR (n_{1}=3). Lines from level n: N = n(n−1)/2.

• Nuclear: R = 1.2×A^(1/3) fm; density constant; BE = $\Delta m$×931.5 MeV; Fe-56 most stable (8.75 MeV/n); fusion (light) and fission (heavy) both release energy.

• Decay law: N = $N_{0}$/2ⁿ after n half-lives; t_{1}/{2} = 0.693/λ; mean life τ = 1.443×t{1}/{2} > t{1}/_{2}.

• Decay types: Alpha: $\Delta A$=−4, $\Delta Z$=−2. β^{-}: $\Delta A$=0, $\Delta Z$=+1. γ: no change. Activity in Bq (SI).