History of Chemistry: Pt. 2

this is a continuation of the last post, looking at the BBC documentary ‘Chemistry: A Volatile History’

The second episode deals with:

• John Dalton‘s (1766 – 1844), who helped develop the modern atomic theory, i.e. elements being made up of smaller particles: atoms. He further suggested that each element was made up of an atom, and that the difference between the atoms of different elements is their weight. He also attempted to put an order to the periodic table.
• Jöns Jacob Berzelius‘s (1779 – 1848) attempt to weigh each element. He aslo discovered Silicon.
• Johann Wolfgang Döbereiner‘s (1780 – 1849), who helped to organize elements based on their reactive/functional properties: i.e. periodic trends 😉
• Stanislao Cannizzaro (1826 – 1910), who enabled a better way of measuring the atomic weight of elements.
• John Newlands‘s law of octaves (sort of like the octet rule). The idea being that every eighth chemical is similar (this only works for the elements 3 to 18, or Lithium to Argon) . He was the first person to devise a periodic table of elements arranged in order of their relative atomic weights.
• Dmitri Mendeleev (1834 – 1907), the discoverer/creator of the modern periodic table (!!!). Also, note that his great insight came in a dream (note: the discovery of the structure of the benzene ring also came from a dream (Friedrich August Kekule von Stradonitz))
  Note: there’s a crater on the moon named after him.
• Gustav Robert Kirchhoff (1824 – 1887) and Robert Bunsen (1811 – 1899; the inventor of the bunsen burner), who together invented spectroscopy (the discovery that each element gave off a unique spectrum when burned).
• William Ramsay (1852 – 1916), who discovered the noble gases.
• Niels Bohr (1885 – 1962), who created the Bohr model of the atom: that electrons travel in discrete orbits around the atom’s nucleus. As well, he created the shell model of the atom: where the chemical properties of an element are determined by the electrons in the outermost orbit.
  This lead to an explanation of why elements are the way they are, and explained the periodic table.
• Henry Moseley (1887 – 1915), who worked with x-ray spectra, to show that elements are made up of a unique amount of protons. It’s this number of protons that determines where the element will be on the periodic table (not the atomic weight).
  He died in battle in WWI 😦

Watch it below: