Chapter 4: Structure of the Atom Test Test Time Explore various categories of non-fiction books. Charged Particles in Matter Discovery of electrons and protons, properties of subatomic particles. The Structure of an Atom Basic concept of atomic structure with nucleus at center containing protons and neutrons. Thomson's Model of the Atom Plum pudding model: atoms as spheres with embedded electrons like plums in pudding. Rutherford's Model of the Atom Gold foil experiment, nucleus as dense center, electrons revolving around it. Drawbacks of Rutherford’s Model Instability of atom due to revolving electrons losing energy and spiraling into nucleus. Bohr's Model of the Atom Electrons revolve in fixed energy levels/shells without radiating energy. Neutrons Discovery by Chadwick, electrically neutral particles in nucleus with mass similar to proton. How Are Electrons Distributed in Different Orbits? Electronic configuration using 2n² rule and examples like hydrogen, carbon, oxygen. Atomic Number and Mass Number Atomic number = number of protons; Mass number = protons + neutrons. Isotopes and Isobars Isotopes: same atomic number, different mass number; Isobars: same mass number, different atomic number.