-
400 BCE
Ancient Greeks Atomic Theory
Democritus created the first atomic theory. He was a greek philosopher in the fifth BC. His theory was if a rock was split in half the two halves would have the same properties as a whole. If the stone was cut into multiple tiny pieces at some point there would be a piece so small to be "atoms" greek for indivisible. The atoms were different in shape, size, constant in motion, colliding with each other either stick or rebound together. Aristotle disproved this theory ignoring it for 2,000 years. -
Christiaan Huygens
Christiaan Huygens was a Dutch physicist. In 1678 believed that light was made up of waves that vibrate up and down perpendicular to the direction that the light travels.The wave theory of light is the discovery of the rings of Saturn and this theory helped people to study the force on bodies -
Isaac Newton
Isaac Newton theorized a mechanical universe with small, solid masses in motion. He studied gases and the possibility of atoms existing and his work was impeded by the church. -
Dalton's Atomic Theory
John Dalton said the atom was a fundamental building block of chemical structures. He believed atomic theory could explain why water absorbed different gases. He developed the law of multiple proportions. He also believed each chemical element is made up of single atoms they cannot be altered or destroyed but can combine together. Since he reached conclusions by experiments it marked the first truly scientific theory of the atom. -
Gustav Kirchhoff
Gustav Kirchhoff became the professor of physics at the University of Heidelberg where he joined with Bunsen and together founded spectrum analysis. They demonstrated that every element gives off a characteristic coloured light when heated. They proved that this light when separated by a prism has a individual wavelength specific for each element. When concluding there findings they discovered two new elements, cesium and rubidium. -
James Maxwell
James Maxwell proposed the theory of electromagnetism and made the connection between light and electromagnetic waves. He was a Scottish physicist that did multiple demonstrations to begin the connection between 2 forces which unexpectedly involved the velocity of light. -
Heinrich Hertz
Heinrich Hertz was the first scientist to prove that electromagnetic waves did have an existence and in doing that he proved the theory that was first put forward by James Maxwell. His theories developed into what later became radio waves and found another conclusion from his research that both light and heat are different forms of electromagnetic radiations. -
JJ Thomson Atomic Theory
JJ Thomson's discovery of the electron changed the way people viewed atoms. Up until the 19th century atoms were thought to be tiny solid spheres. He made a model of the atom consisting of positive and negative charges with equal amounts so it would be electrically neutral. He created the plum pudding model. Modern scientists understood atoms consist of a nucleus of positively charged protons and neutral neutrons with negatively charged electrons orbiting the nucleus. -
Max Planck
In 1900 he proposed the idea of quantization to explain how a hot, glowing object emitted light. Max was a German physicist and was best known as the originator of the quantum theory and was awarded the Nobel Prize in 1918. His work gave understanding of atomic and subatomic processes. -
Albert Einstein
Albert Einstein treated matter and energy as exchangeable and became famous for the theory of relativity which laid the basis for the release of atomic energy. In 1905 he wrote a paper that explained that light absorption can release electrons from atoms. He calculated size molecules and atoms. -
Ernest Rutherford
Rutherford disproved Thomson's theory in 1911 with doing the "gold foil" experiment. He demenstrated that the atom has a tiny and heavy nucleus. If Thomson was correct the beam would go straight through the gold foil. Most of the beams went through but a few were reflected. The atom is not a single particle but is made up of far smaller sub atomic particles. The atomic system was similar to the solar system where electrons revolve around the suns electrostatic force rather then gravity. -
Neils Bohr Atomic Theory
The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. He was first to discover that electrons travel in separate orbits around the nucleus. Also, that the number of electrons in the outer orbit determines the properties of an element. In these orbits the electrons wouldn't lose any energy so they don't collapse into the nucleus. The orbits are to be placed at a certain distance away from the nucleus in the center, each one with a certain energy.
