More about the composition of an Atom.

The atom is the energy or force that creates “matter”, but what is the atom?  It is too small to be seen or examined, throughout the ages, great men have attempted to understand the composition of the atom. It took the invention of a Scanning Tunneling Microscope in the 20th Century to partially view the presence of atoms on the surface area of metals.

The Danish scientist Bohr (Boor) theorized that the atom is like a miniature solar system, with a core that has small planets (electrons) revolving around it in orbit. His model left some questions about the atom.

The Physicist, Louis de Broglie suggested that an electron is like light, that is, it can behave like a particle and also as a wave. Experiments supported his hypothesis. We now believe that the movement of an electron around the nucleus of the atom sets up a wave of specific frequency and energy.

The German Physicist, Werner Heisenberg determined that one could not measure the position of an electron moving about its atom because the measurement energy to locate the electron caused it to change its path.

This effect is called the Heisenberg Uncertainty Principle.

Then an Austrian Physicist named Irwin Schrodinger developed a set of mathematical equations to describe standing waves generated by the probable motion of electrons orbiting anround the atoms nucleus, resulting in the quantum model.

In the 1960’s experiments with atomic particles indicated that protons and neutrons have an internal structure and therefore must be made of still smaller particles.  Their discoverer the theoretical physicist Dr. Murray Gell-Mann called them “quarks”. Six types: Called up, down, strange, charmed, top, and bottom have been identified. A proton consists of two up quarks and one down quark, while a neutron is made of two down quarks and one up quark. Combinations of quarks yield more particles, although most are unstable and decay quickly to protons or neutrons.

A view taken by a NIST Scanning Tunneling Microscope shows the electron cloud formation of atoms on the surface of metal.

Picture source:  NIST
STM image, 7 nm x 7 nm, of a single zig-zag chain of Cs atoms (red) on the GaAs(110) surface (blue).
Reference: Geometric and Electronic Properties of Cs Structures on III-V (110) Surfaces: From 1-D and 2-D Insulators to 3-D Metals, L.J. Whitman, J.A. Stroscio, R.A. Dragoset, and R.J. Celotta, Phys. Rev. Lett. 66, 1338 (1991).