-
Isaac Newton
English Phycisist, proposed a mechanical universe with small solid masses in motion. -
Law of Conservation of Mass
Antwan Lavoisier of France determined that matter cannot be created nor destroyed, but only appear in a different form. He also defined the difference between and element and a compound. His law of conservation of mass (during a chmical reaction, the mass of the reactants is the same as the mass of the products.) guided many other scientists to make other scientific discoveries. But because he was a nobleman, and a tax collector, he was excecuted at the Guillotine during the French Revolution. -
Joseph Preistley
Preistley was originally an English chemist from Birmingham. However, the people beleived he was in support of the American Revolution, and so he was forced to flee to America, Most of the laboratory equipment and scientific records he had were destroyed by rioters who burned his house and church. Despite this, by heating red mercury oxide, he was the first to isolate elemental oxygen -
Dalton's work
John Dalton, an Englsih chemist performed experiments that proved that all matter was made from tiny indivisible atoms. He then represented elements and compounds with circles and letters of the alphabet. He also proposed that every atom of an element had same weight and properties, all atoms of an element have the same weight and properties, different elements' atoms had different weights and much more. It was a great leap in scientific discovery. -
Weighing the Atoms
Jons Jakob Berzelius was able to accurately measure the weights of a variety of atoms, and published them in 1828. Just as importantly, he came up with the idea to use letters to represent the names of elements -
The Periodic Law
Dmitri Medeleev arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of their atomic weights". This became known as the Periodic Law. With this, he was able to construct the Periodic Table. He grouped elements with similar properties into vertical groups, and in order of increasing atomic mass into periods. However, as there were still many elements to discover, there were gaps on the first table. -
JJ Thompson
Thompson, and English Physicist, discovered the electron and proposed his "Rasin in the Pudding" model of the atom. He knew that electrons were negatively charged, and beleived that that meant that matter was positively charged. -
Radioactivity
Marie Sklodowska Curie studied uranium and thorium and called their decay process "radioactivity". She and her husband Pierre Curie also discovered the radioactive elements polonium and radium. -
Max Phlanck
Phlanck was a Professor of Theoretical Physics based in Berlin, Germany. He showed that when you make atoms vibrate with a stong force, it is possible to measure the energy, but in discrete units only. He called these energy units "quantas" -
Saturnian Model of the Atom
Nagaoka Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle. -
Albert Einstein
Albert Einstein wrote a ground-breaking paper that explained that light absorption can release electrons from atoms, a phenomenon called the "photoelectric effect." -
Mass and Weight of the Electron
R.A. Millikan, in an oil drop experiment, determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron. -
Neils Bohr
Bohr ,renowned for his "Bohr Modeldevise" ,devised two rules which contributed to the understanding atomic structure.The two rules were:
• RULE 1: Electrons can orbit only at certain allowed distances from the nucleus.
• RULE 2: Atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit. Also, atoms absorb energy when its electrons are boosted from a low enegery level, to a high one. Bohr received the Nobel Prize for Physics in 1922. -
Einstein wins Nobel Prize
Albert Einstein received his only Nobel Prize for his work on the photoelectric effect. -
Pauli's Exclusion Principle
Austrian Physicist Wolfgang Pauli deduced that electrons “spin” as they orbit the nucleus. Pauli designed a rule governing the behaviour of electrons within the atom that agreed with experiment - if an electron has a certain set of quantum numbers, then no other electron in that atom can have the same set. This is called "Pauli's exclusion principle.” -
Stars and Hydrogen and Helium
Cecelia Payne determines that the Sun and other stars were composed almost entirely by hydrgen and helium. -
The Shroedinger Equation
Erwin Shroedinger on Austria, in this year, introduced the Shroedinger Equation. It is a wave equation that describes the form of the probability waves that govern the motion of small particles and the way these waves are affected by foreign influences -
The Uncertainty Theory
Werner Heinsenberger publishes his "Uncertainty Theory," It read: "The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa." -
Dirac's Prediction
Paul Dirac finds that there are in fact not one, but two solutions to the equation which determined the way electrons behaved, thus predicting the existence of a positively charged electron. -
Discovery of the Proton and Positron
It was not until this year, that the neuton was finally discovered by English Physicist James Chadwick. Also in this year, Carl Anderson proves the existence of a positively charged electron, called the positron. -
Virtual Photons
Werner Heisenberg concluded that charged particles bounce light to and from each other. This exchange of photons provides a way for the electromagnetic forces to act between the particles. These exchanges happen all the time, very quickly -
Discovery of the Antiproton and the Antineutron
Scientists discover the antiproton, and later, the antineutron. -
The Eightfold Way
In 1960, Murray Gell-Mann and Yuval Ne'man proposed a method for categorizing all the particles then known. The method became known as the Eightfold Way. What the Eightfold Way did for particles, is like what the Periodic table did for elements. -
Quarks
In 1964 Murray Gell-Mann proposed the existence of a new level of elementary particles - "quarks." These little bits of matter which when used kind of like building blocks, serve to explain some complex chemical substances.
