Austrian physicist Erwin Schrödinger (1887-1961) developed an “Electron Cloud Model” in 1926.  It consisted of a dense nucleus surrounded by a cloud of electrons at various levels in orbitals.   Schrödinger  and Werner Heisenburg (1901-1976) mathematically determined regions in which electrons would be most likely found.   The probability of the finding the electrons in the orbitals are sometimes referred to as “lobes.” They used the mathematical equations for the behavior of waves following the work on waves by Louis de Broglie (1892-1987) a French theorist. 

It is still impossible to see a single atom, even with the world’s best microscopes, but we can see images of groups of atoms, and the trails that they leave.  Starting in the 1950’s, experiments using the newly invented particle accelerators and particle detectors opened up a new age of “particle physics.”   Through the last half century individual particles were identified by teams of researchers in only certain facilities around the world.   Fermilab in Illinois,  Stanford Linear Accelerator Center (SLAC) in California,  Brookhaven in New York, CERN the European Laboratory  near Geneva, Switzerland,  and  DESY in Hamburg ,Germany  will continue to refine the individual particles with every experiment.  They are still working on discovering particles that will fully prove a Standard Model, which not only explains how atoms work, but how atoms are part of a Unifying Theory.  We will visit this again in later chapters.