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Democritus
• Democritus atomic theory says that atoms are found in the earth’s atmosphere.
• Atoms cannot be separated or atoms are invincible. • Democritus’ atomic theory posited that all matter is made up small indestructible units he called atoms.
• Democritus lived in Greek from 460 BC to 370 BC, he was a philosopher. -
Isaac Newton
• Isaac Newton theorized a mechanical universe with small, solid masses in motion.
• Isaac Newton was a physicist and mathematician who lived in England; Newton lived from 1642 to 1727. -
John Dalton John Dalton
• John Dalton’s atomic theory says that matter is made out of atoms.
• That atoms are unbreakable.
• All atoms at the same element are the same in properties and mass.
• John Dalton lived in England from 1766 to 1844, he was a chemist, meteorologist and a physicist. -
Michael Faraday
• Michael Faraday developed the two laws of electrochemistry.
• Faraday studied electricity’s effect on solutions, also known as ‘electrolysis’, meaning the splitting of molecules with electricity • Michael Faraday was an English scientist who majored in Physics and Chemistry who lived from 1791 to 1867. -
William Thomson
▪ Both Mathematician and physicist William Thomson was the first to try and construct a physical model of the atom. Inspired by Helmholtz who proposed that an vortex line has the same particles and thus is unbroken making it ring like. It was this that made Thomson believe that atoms were like vortices
▪ William Thomas was born in Britain; he was a mathematical physicist and engineer. William lived from 1824 to 1907. -
Dmitri Mendeleev
• Dmitri Mendeleev was the person to arrange the elements into the 7 groups with similar properties.
• Mendeleev discovered that properties of elements “were periodic functions of their atomic weights’. This become what we know as today as the Periodic Law or Periodic Table.
• Dmitri Mendeleev 1834 to 1907, was an Russian inventor and chemist. -
James Clerk Maxwell
• James Clerk Maxwell suggested the theory of electromagnetism and made the link between light and electromagnetic waves. • James Clerk Maxwell was a Scottish theoretical physicist who lived from 1831 to 1879. -
G.J Stoney
• George Johnstone Stoney established the term ‘electron’ as the basic unit quantity of electricity. • Stoney was an Ango-Irish physicist, who lived from 1826 to 1911. -
Max Planck
• Max Planck was a theoretical physicist who originated in Germany who lived from 1858 to 1947• Planck established the quantum theory; A theory of matter and energy based on the concept of quantum mechanics. -
Frederick Soddy
• Frederick Soddy suggested that the same elements exist in different forms, with nuclei having the same amount of protons but different amounts of neutrons. • Soddy’s theory on isotopes explains that other elements are able to be chemically indistinguishable but have different atomic characteristics and weights. • Frederick Soddy originated from England, he was an radio chemist and monetary economists, Frederick lived from 1877 to 1956. -
Hantaro Nagaoka
▪ Nagaoka created a planetary model of an atom. The model of the atom made two main predictions, 1. A very massive nucleus 2. Electrons revolving around the nucleus, bound by electrostatic forces.▪ Hantaro Nagaoka was a Japanese physicist and a pioneer of Japanese physics, he lived from 1865 to 1950. -
Hans Geiger
▪ Johannes ‘Hans’ Geiger co-invented the Geiger counter, which could detect alpha particles, and the Geiger-Marsden experiment helped them discover the atomic nucleus.▪ Johannes ‘Hans’ Geiger lived from 1882 to 1945; he originated from Germany and worked as a physicist and inventor. -
Henry Moseley
▪ Moseley changed the idea of atomic numbers from ad hoc numerical tag which helped the sorting of the elements, into the Periodic Table, he then changed it into a real and objective whole-number quantity that was experimentally measurable.▪ Henry Moseley was an English physicist, who lived from 1887 to 1915. -
Niels Bohr
▪ Niels Bohr contribution to the atom model helped greatly improve our understanding of the atom in general. He was only able to do so thanks to Rutherford early model of the atom saying that it had a positively charged nucleus with a negatively charged electron orbiting the nucleus. Bohr then proposed that electrons orbited in larger orbits and that the farther away the electron is from the nucleus the more electrons that layer can hold. And it is this that determines the chemical property. -
Erwin Schrodinger
▪ Erwin Schrodinger lived from 1887 to 1961, he was an Australian Physicist.▪ Erwin Schrodinger came and finalized the puzzle about the electron arrangement. He stated that electrons behave more like waves and for this reason could not be precisely calculated. He also theorized that each electron had a sub shell equal to the number shell number.
