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John Dalton
He came up with the 'Atomic Theory of Matter'. He stated that matter cannot be broken down any more when it's an atom particle and that atoms are the shape of a sphere. He also said that everything is made up of atoms. He came up with the 'Law of Simple Multiple Proportions', it's when elements are put together and they combine in fixed, simple ratios. No two elements have the same atoms because they all weigh differently but the same elements have the same atoms meaning they weigh the same. -
J.J Thomson
J.J Thomson realized that atoms can be broken down into electrons, therefore discovering the electron and isotope. Using the Cathode ray tube, it emitted rays from a cathode in a tube. He found that the negatively charged particles were attracted to the positively charged anode. He also came up with the ‘plum pudding model’ and showed that the plums are the electrons and the dough is the rest of the atom. -
Marie Curie
Marie Curie is well known for her discoveries with radiation. In France, Marie and her husband found out that some elements and atoms could emit strong rays, called ‘radioactivity’. While doing this, they discovered the elements Radium and Polonium while examining a mineral called pitchblende. She also discovered that more radiation would come out if she was using more uranium. -
Ernest Rutherford
Ernest Rutherford conducted the ‘gold foil experiment’. He used a thin layer of gold and shot alpha particles through it. He then found out that the alpha particles had gone straight through the foil, proving that the gold atom was made up of a lot of space. By doing this, he came up with the theory of how an atom is structured. An atom would have a nucleus, which is dense, small in size and positively charged. -
Niels Bohr
In 1913, Niels Bohr had come up with the theory that atoms have shells by using the ‘Bohr atomic model’ he had made. The model showed that electrons orbited in shells around the nucleus. So if the electrons carried more energy, they would orbit in their shell more further away from the nucleus. Also, the amount of electrons there are in the outer shell, tells you what element it is. -
Henry Moseley
To conduct his experiments, Henry Moseley used X-rays. By doing this, he discovered what we now know as Moseley’s law. Henry discovered that there was a relationship between wavelengths and atomic numbers. He showed that the element’s atomic number is how many protons there are in its nucleus. By showing this, the periodic table was reorganized. -
Francis Aston
Francis Aston had invented the mass spectrograph. A mass spectrograph has the capability of detecting particles photographically, and when he was examining the element Neon, he saw that there were two curves in the photograph, which meant that the element was made up of two different atoms which are the same chemically, but weighed differently. In doing this, he discovered the isotope. -
Erwin Schrodinger
From Austria, Schrodinger was the scientist who came up with the “Electron Cloud Theory”. He stated that electrons that move in an atom, are also usually moving in a wave. He used mathematic equations to predict and show where an electron can be located at a given time, meaning electrons will be in different spots each time you look at it. -
James Chadwick
James Chadwick in 1932 had proven that neutrons did exist in atoms. He also was able to figure out the mass of neutrons. Leading to his discovery of the neutron, he had shown that in the chemical reaction of alfa particles against beryllium, a particle with no charge about the same size of a proton was released, therefore proving that neutrons exist. -
Murray Gell-Mann
Recently, in 1964, Gell-Mann, a physicist from the United States had proved that ‘quarks’ exist. To prove that particles could not split, he used the quark model he had made. Although you cannot see them, all particles in the nucleus, are also made up of even smaller particles holding a bit of charge, known as quarks.
