2.0 The Changing atom

In this OCR A Level Chemistry video, award-winning science teacher Dr. David Boyce expertly guides students through the evolution of atomic theory from Democritus to Schrödinger. Dr. Boyce begins with Democritus's ancient concept of indivisible particles called "atomos." He then transitions to John Dalton's 19th-century atomic theory, highlighting key principles such as atomic indivisibility and fixed ratios in compounds. The journey continues with J.J. Thomson's discovery of the electron and his "plum pudding" model, followed by Ernest Rutherford's groundbreaking gold foil experiment, revealing a dense, positive nucleus. Niels Bohr's model introduces quantized electron orbits, laying the groundwork for modern atomic theory. Finally, Dr. Boyce explains Schrödinger's wave mechanics, which describe electrons as wavefunctions within orbitals, encapsulating the probabilistic nature of their behaviour. This engaging and informative video offers a comprehensive overview of atomic model development, tailored for A Level Chemistry students.