• Tags: bohr, limitations, quantum
• Difficulty: Moderate

Bohr model limitations: (1) Only works for hydrogen-like atoms (one electron). Fails for helium and beyond. (2) Cannot explain fine structure of spectral lines $\frac{splitting in magnetic}{electric fields}$. (3) Cannot predict transition rates (which transitions are more likely). (4) Cannot explain molecular bonding or chemical behavior. (5) Assumes well-defined orbits, violating the uncertainty principle. (6) Does not account for relativistic effects. The modern quantum mechanical model (Schrödinger equation) resolves these issues by replacing orbits with orbitals (probability clouds) and introducing quantum numbers (n, l, $m_l$, $m_s$). However, the Bohr model gives correct energies for hydrogen-like atoms and is sufficient for JEE.