![]() ![]() The boxes that make up the periodic table contain a significant amount of information. In 1914, his work led to a revision of the periodic table by rearranging the elements by their atomic numbers He concluded that the number of protons in an atom is its atomic number Sample X-ray Spectra Image taken from: “Ekasilicon” Germanium Notice how Mendeleev’s predictions (orange column) were very accurate when compared to Germanium’s actual characteristics (green column) Date Predicted 1871 Date Discovered 1886 Atomic Mass 72 72.6 Density 5.5 g/cm3 5.47 g/cm3 Bonding Power 4 Color Dark Gray Grayish White Why do you think there are question marks here? Image taken from:Īlthough Mendeleev’s Periodic Table of Elements had missing elements or “gaps,” he was able to predict the characteristics of these missing elements because of Periodic Law. Something periodic occurs at regular or at least generally predictable intervals Periodic law - physical and chemical properties of the elements are periodic functions of their atomic numbers Periodic Table of Elements – a table of the elements, arranged by atomic number, that shows the patterns in their properties based on the periodic law Can you think of anything that is periodic?ģ Element A pure substance made up of one kind of atom that cannot be broken down into simpler substances by physical or chemical means 90 occur naturally on earth 25 were synthesized (made) by scientists Element SongĤ Dmitri Mendeleev In the 1860’s he devised a periodic table where the elements were ordered by their atomic masses He did this by grouping elements together according to their similarities Draft of Mendeleev's Periodic Table Image taken from:ĥ Mendeleev’s Published Periodic Table of Elements 2 Periodic Periodic Law Periodic Table ![]()
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