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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.
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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
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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
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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
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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.
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John Davy (1788-1829)
Other discoveries Nitrous oxide (laughing gas)
Inventions One of the first light bulbs Miner headlamps
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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.
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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.
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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.
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His periodic table grouped similar elements into columns - just like ours does today
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Will It Ever End!
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