atomic-structure

# Atomic Structure All chemistry rests on atoms. Understanding how atoms are built — their subatomic particles, electron arrangements, and position in the periodic table — is the foundation for predicting chemical behavior. This skill covers atomic models from Dalton to quantum mechanics, electron configuration rules, periodic table organization, periodic trends, and isotopes with radioactivity. **Agent affinity:** mendeleev (periodic/inorganic chemistry, primary), curie-m (nuclear/radiochemistry, for isotope and decay topics) **Concept IDs:** chem-atomic-structure, chem-periodic-table-organization, chem-periodic-trends, chem-isotopes-radioactivity ## Historical Atomic Models | # | Model | Year | Key idea | Limitation | |---|---|---|---|---| | 1 | Dalton | 1803 | Indivisible solid spheres | No internal structure | | 2 | Thomson | 1897 | "Plum pudding" — electrons in positive matrix | No nucleus | | 3 | Rutherford | 1911 | Dense positive nucleus, electrons orbit | Classical orbits radiate energy, collapse | | 4 | Bohr | 1913 | Quantized circular orbits, energy levels | Only works for hydrogen | | 5 | Quantum mechanical | 1926 | Probability orbitals (Schrodinger equation) | Full model — currently accepted | Each model was displaced by experimental evidence the previous model could not explain. Rutherford's gold foil experiment demolished Thomson's model. Bohr's model explained hydrogen line spectra but failed for multi-electron atoms. The quantum mechanical model, based o...