1The birth of quantum mechanics:A historical overview of a scientific revolution(1900-1930)19011918190519211913192219241929192619341927193219271954Who needs Quantum-mechanics???•Why are atoms stable?•What distinguishes atoms of different chemical elementsfrom one another (The periodic table)?•Why do atoms form chemical bonds (molecules)?•What is holding the atoms in liquids and solids together?•How do atoms, molecules and other molecular assemblies interact with light? Chemistry is the science of atoms, how they assemble to form molecules, and how these molecules assemble to formmaterials. The driving forces underlying the most fundamentalchemical processes can only be explained by the theory of Quantum Mechanics. Understanding of the most fundamental processes underlying chemistry is based on quantum mechanics!
has intentionally blurred sections.
Sign up to view the full version.
2Historical outline of the atomic theory of matter1.5-th century B.C:The Greek philosopher Democritus postulates the existence of atoms (“indivisibles”) as the fundamental building blocks of matter.2.18-th -19-th centuries:European scientists (Lavoisier, Proust,Dalton, Gay-Lussac, Avogadro) gather indirect, but rather overwhelming experimental evidence for the existence of atoms (the laws of chemical combination). 3.Late 19-th – Early 20-th centuries:Atoms are divisible! Anatom consists of a positively charged, extremely small and very massive nucleus, surrounded by negatively charged and extremely light electrons. The nucleus is made of Z positively charged protons and N neutral neutrons (A=N+Z is the mass number). The electronic and protonic charges are equal, such that there are Z electrons and the atom as a whole is neutral.(Thomson, Millikan, Ratherford). Millikan’s oil drop Experiment (1906)Thomson’s Cathode Ray Tube (CRT) Experiment (1897)Cathode rays consist of particles that we now call electrons.Rutherford alpha particleScattering (1911)(The discovery of the nucleus and “planetary” model of the atom).111/1.75910e mC kg−=×19311.602109.10910eeCmkg−−=×⇒=×