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John Dalton
John Dalton put forward the Atomic Theory that proposed matter was made up of small particles called atoms, that were indivisible, that atoms of different elements had varied characteristics and weight. He also claimed that there were 3 types of atoms, elements, simple (elements), compound (molecules) and complex (molecules). -
JJ Thompson
J.J Thompson was the first man to come across the existence of electrons and measure it. He came up with a method that could separate different atoms and molecules using positive rays (protons and positive ions). He stated that the atom was like a “slightly positive sphere with small electrons inside”. -
Marie Curie
Marie Curie and husband Pierre discovered two new elements while studying pitchblende. She named them polonium and radium. The Curies also created the term radioactivity, which was used to describe the strong ray emitting elements. Marie declared that the break down in atoms are caused by radioactive materials, which releases energy and subatomic particles, both forms of radiation. -
Period: to
Ernest Rutherford
Ernest Rutherford discovered that the atomic nucleus existed during an experiment involving gold foil. He was also heavily involved in coming up with a simplified model of the atom, that then became widely popular and well-known. He claimed that each atom was composed of a nucleus, electrons floating around it. In 1918, he discovered protons. -
Niels Bohr
Niels BohrNiels Bohr came up with a model of atomic structure that pointed out three things: electrons move around the nucleus and their orbit has a specific size and amount of energy, the energy and size of an orbit are relative to each other and when an electron changes orbits, radiation is absorbed or emitted. -
Henry Moseley
Henry made a discovery now known as Moseley’s Law, where in which he found out the structured relationship between wavelength and atomic number. This discovery contributed in the sorting of the elements in the periodic table by order of their atomic numbers. With his new table intact, it demonstrated the blank spaces for soon-to-be discovered elements. -
Francis Aston
Francis Aston invented mass spectrograph, an invention he used to become the first person to observe isotopes, including three different types of hydrogen atoms. His discoveries made it easier for other scientists to investigate nuclear masses and paved the way for atomic energy and weapons. Without his work, it would not have been possible for Rutherford to predict the neutron. -
Erwin Schrödinger
Erwin Schrödinger developed a model of an atom that showed where the electrons were most likely to be. He also explained an electrons movement in an atom was wave-like. He formed a math equation (now developed a model of an atom that showed where the electrons were most likely to be. He also explained an electrons movement in an atom was wave-like. He formed a math equation (now known as the Schrödinger Wave Equation) that describes how, over time, the quantum state of a system changes. -
James Chadwick
Chadwick discovered the neutron in the atomic nucleus. In discovering this, he supplied the response to the question of what was the mass hidden in atoms, and made it possible for labs to produce elements that are heavier than uranium. Unfortunately, his discovery contributed in the invention of the atomic bomb. -
Period: to
Murray Gell-Mann
Murray Gell-Man contributed to the atomic theory in his work in classifying the subatomic particles. In 1964, he put forward the existence of quarks, fast moving points of energy. He demonstrated that quarks are what make up protons, neutrons and matter itself. He stated that each proton and neutron contains three quarks in them. This discovery built up more evidence to prove that his Eightfold Way was in fact, accurate.
