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John Dalton
He proposed the idea of atomic theory. This stated that all matter is made up of tiny inseparable particles called atoms. Atoms in elements have different and unique features and weight. He also discovered that there were three types of atoms, simple(elements), compound (simple molecules and complex (complex molecules) -
Joesph John Thomson 1897-1904
Discovered the electron while he was conducting many experiments to study the nature of electrical discharge. He did this by showing that cathode rays were made up of negative charged particles and finding out and naming these negatively charged particles as electrons. He also found the first evidence/prove of isotopes when he was exploring canal rays. In 1904 he made a plum pudding model of an atom with its electrons. -
Marie Curie
Marie Curie discovered the radioactive elements polonium and radium. She discovered this with her husband by isolating various substances by chemical reactions and crystallizations. After they isolating the various substances they tested its ability to convert into an ion with air They found polonium. After Marie Curie’s husband died she achieved producing a pure specimen of radium. -
Ernest Rutherford
Ernest Rutherford discovered that the atom has central nucleus which is positive.He thought of the idea that surrounding the nucleus are electrons that are orbiting around the nucleus. He also discovered,after his famous “gold foil experiment” that most of the atom is made up of empty space. -
Niels Bohr
Niels Bohr discovered that electrons travel in separate orbits. He also discovered that the properties of an element was determined on the number of electrons in the outer orbit. He made a small model of an atom that had a positively charged nucleus that was charged by electrons that were surrounding and orbiting the nucleus. -
Henry Moseley
Henry Moseley established the Periodic Table of Elements. He established this by sorting the chemical elements in the order of their atomic number. He observed the properties of x-rays and discovered that as the x-rays wavelength become shorter the atomic weight increased. Using this information he then worked out the atomic number and began establishing the periodic table. -
Francis W. Aston
Francis Aston found a way to separate isotopes of a neon. He did this by inventing the mass spectrograph. Using the spectrograph he found that of the chemical elements, two hundred and twelve of them were naturally occurring isotopes.He then formulated a rule(Whole Number Rule) that found the mass of a oxygen isotope being defined and the mass of the other isotopes. -
Erwin Schrodinger
He developed a powerful model of the atom. Erwin generated a mathematical model for the distributions of electrons by combining the equations for the behaviour of waves and the de Broglie equation to create the model. The model was one dimensional which only used one quantum number to describe the distributions of electrons in the atom. He discovered that his model allowed the electron to take up three dimensions of space therefore it required three quantum numbers. -
James Chadwick
James Chadwick discovered the neutron. He discovered the neutron in a reaction. He showed that a neutral particle was emitted from the nucleus that was around the mass of about a proton. Other scientist like Ernest Rutherford had earlier found that a neutral particle may exist in the nucleus but it was James Chadwick who actually found the evidence that a neutral particle really existed in the nucleus. He named the neutral particle a neutron. -
Murray Gell-Mann
Murray Gell-Mann discovered the quark. He thought of the concept of the eight way fold scheme and by using this concept he found around 100 different kinds of particle collision involving atomic nuclei. Murray also found that the particles were made up of “fundamental building blocks”. He named these building blocks quarks and found that they had unusual properties.
