Elements

First noticed by Greek people in about 400BC. They used the words“element”, and “atom” to describe the differences and smallest parts ofmatter. Those ideas lasted for 2000 years. Elements were Earth, Fire, Air,and Water that explained “world stuff” easily came and went. In the 1600’s Boyle, an experimenter, influenced by Democritus,Gassendi, and Descartes lent important weight to the atomic theory ofmatter. In the 1700’s Lavoisier divided the elements into four classes. John Dalton suggested that the mass of an atom is the important property. “The chemical elements are composed of... indivisible particles ofmatter, called atoms... atoms of the same element are identical in allrespects, particularly weight.” n the 1800’s Doereiner said that some elements had a relative atomicmass, and DeChancourtois made a table of elements to show the periodicreoccurrence of properties. In the 1860’s Newland made a table ofelements giving them a serial number in order of their atomic weighsstarting with Hydrogen. Meyer and Mendeleyev made periodic tables independently. Meyermade it more periodicity of physical properties, and Mendeleyev made itmore on the chemical properties. Mendeleyev published his periodic table& law in 1869. Periodic tables have always been related to how scientiststhought about the shape and structure of the atom. Later, the table wasreordered by Mosely according to atomic numbers(nuclear charge) insteadof weight. Harry D. Hubbard, of the United States National Bureau ofStandards, modernized Mendeleyev’s periodic table. It got published in1924. It was called the “Periodic Chart of the Atoms.” In the 1930’s the heaviest elements were being put into theperiodis table. The Alexander Arrangement of the Elements, athree-dimensional periodic chart designed and patented by Roy Ale...