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Newton proposed a mechanical universe with small solid masses in motion.
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Dalton discovered that the known elements combined indefinite constant proportions. Elements must be made of smaller invisible pieces of matter with relative and distinctive weights. He called the pieces of matter atoms. He also found relative weights of ultimate particles. Which was later called atomic weights. Dalton made the idea of an atom useful by comparing the things chemists do, weigh things and balance, with the things you can’t see.
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Faraday studied the effect of electricity on solutions. Coined the term "electrolysis" as a splitting of molecules with electricity. He also developed laws of electrolysis.
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Mendeleev arranged the elements into 7 groups with similar properties. He also discovered that the properties of elements "were periodic functions of the their atomic weights".
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He stated atoms were not simple solid spheres. Most notably Thomson discovered electrons. Which are small particles located outside the nucleus and have negative charge. Which causes the metal needle in a compass to point north
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Rutherford developed a more complete understanding of the structure of atoms. He found that atoms are mostly made of space, and some atoms have a small dense positively charged center, the nucleus, that repels the positively charged bullets in his experiment with a gold foil experiment. He also discovered all of an atoms positively charged particles are in the nucleus and negatively charged particles are scattered outside the nucleus around on
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BOhr proposed that electrons orbit around the nucleus. Each electron has a fixed amount of energy. He also found that electrons orbit within energy levels forming rings around the nucleus. By absorbing or releasing energy an electron can move between energy levels.
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Moseley determined the charges on the nuclei of most atoms. And the atomic number of an element is equal to the number of protons in the nucleus.
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By using alpha particles Chadwick discovered a neutral atomic particle with a mass close to a proton, which was the neutron.
