9/25/2019 The History of the Periodic Table Chemistry Section 5-1 Targets for Today Describe the concept of alchemy Describe early scientific breakthroughs in the discovery of elements Explain how the modern periodic table is constructed. 1 9/25/2019 The Discovery of Elements The world is made out of stuff People have known and named specific elements since ancient times Earliest elements discovered Ex. Gold, silver, tin, copper, lead, mercury 2 9/25/2019 I discovered something, but what is it? Early alchemists isolated some elements from compounds, though they didn’t know they had the first pure element. Alchemy – a scientists whose goal is to turn basic metals (ex. Copper) into gold 3 9/25/2019 The first true element - Phosphorus In 1669 an alchemist in Hamburg, Germany named Hennig Brand was the first person to discover an element and know what it was. Hennig Brand He discovered phosphorus after isolating it from urine… over 1,200 gallons of it! As he boiled it down in an attempt to make a “sorcerer’s stone,” a yellowish- green powder remained 4 9/25/2019 Phosphorus Characteristics Atomic # 15 White powder that emits a faint glow when exposed to oxygen Only water and calcium make up more of your bodies weight John Davy (1788-1829) Davy discovered a love of chemistry at age 19, and became one of the most celebrated chemists of his day. He discovered a number of elements, including: calcium, sodium, potassium, magnesium, and others. 5 9/25/2019 John Davy (1788-1829) Other discoveries Nitrous oxide (laughing gas) Inventions One of the first light bulbs Miner headlamps 6 9/25/2019 Radioactive Elements In 1891 the first radioactive elements was discovered – Uranium (#92) Its unusual properties were not discovered until much later. The Noble Gases In 1868 a new gas (helium) was discovered, which had been previously overlooked because it was inert. Soon other similar gases were discovered, and they nonreactive gases were given the name noble gases. 7 9/25/2019 Insert Video Here The First Periodic Table Alexandre de Chancourtois (a French geologist) was the first to produce a periodic table with elements listed based on atomic mass (1862) His periodic table contained all of the known elements at the time – 53 in all. 8 9/25/2019 The Modern Periodic Table Dmitri Mendeleev, a Russian chemist and inventor, published the periodic table in the form we use today. Mendeleev His periodic table was also based on atomic mass, though he had the foresight to leave empty spaces on the table for the elements he knew would be discovered in the future. 9 9/25/2019 His periodic table grouped similar elements into columns - just like ours does today 10 9/25/2019 Will It Ever End! 11.