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4.1
1. The modern periodic table evolved over time through the work of multiple scientists in the 19th century who organized the known elements in different ways. 2. Mendeleev published one of the first recognizable periodic tables in 1869, arranging elements by atomic mass and leaving spaces for undiscovered elements. 3. Mendeleev's predictions about three unknown elements were later confirmed, supporting his periodic law and establishing him as the father of the periodic table.
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4.1
- 1. The History ofthe Modern Periodic Table
- 2. Johann Dobereiner Modelof triads In 1829, classified elements into groups of three, which he called triads. Elements in a triad had similar chemical properties &orderly physical properties. ex. Cl, Br, I and Ca, Sr, Ba
- 3. John Newlands Lawof Octaves In 1863, he suggested that elements be arranged in “octaves” because he noticed (after arranging the elements in order of increasing atomic mass) that certain properties repeated every 8th element.
- 4. John Newlands Lawof Octaves Newlands' claim to see a repeating pattern was not accepted. His classification of the elements was rejected for publication by the Chemical Society.
- 5. Dmitri Mendeleev In1869 he published a table of the elements organized by increasing atomic mass.
- 6. Lothar Meyer Atthe same time as Mendeleev, he published his own table of the elements organized by increasing atomic mass.
- 7. Elements known atthis time
- 8. Both Mendeleev andMeyer arranged the elements in order of increasing atomic mass. Both left vacant spaces where unknown elements should fit. So why is Mendeleev called the “father of the modern periodic table” and not Meyer, or both?
- 9. Stated that ifthe atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong. (He corrected the atomic masses of Be, In, and U) Used his table to predict the physical properties of three elements that were yet unknown. Mendeleev...
- 10. After the discoveryof these unknown elements between 1874 and 1885, and the fact that Mendeleev’s predictions for Sc, Ga, & Ge were amazingly close to the actual values, his table was generally accepted.
- 11. Henry Moseley In1913, through his work with X-rays, he determined the actual nuclear charge (atomic number) of the elements*. He rearranged the elements in order of increasing atomic number.
- 12. Glenn T. SeaborgAfter co-discovering 10 new elements, in 1944 he moved 14 elements out of the main body of the periodic table to their current location below the Lanthanide series. These became known as the Actinide series.
- 13. Glenn T. SeaborgHe is the only person to have an element named after him while still alive.
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- 15. The horizontal rowsof the periodic table are called PERIODS.
- 16. The vertical columnsof the periodic table are called GROUPS , or FAMILIES. The elements in any group of the periodic table have similar physical and chemical properties!
- 17. Periodic Law Whenelements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.
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- 21. InnerTransition Metals Theseelements are also called the rare-earth elements.
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- 24. The s andp block elements are called REPRESENTATIVE ELEMENTS.