Question

3) Describe how the model of an atom has changed over time. 3 sentence

Answer 1

Early ideas and 19th-century chemistry treated atoms as indivisible particles or solid spheres with fixed masses. In the early 20th century experiments revealed internal structure—electrons (Thomson), a tiny dense nucleus (Rutherford)—and Bohr proposed quantized electron orbits to explain spectra. Quantum mechanics later replaced fixed orbits with probabilistic electron clouds (orbitals) described by wavefunctions, forming the modern atomic model.