1. HISTORY OF THE PERIODIC TABLE

2. What is the periodic table? How is it arranged?

3. A brief history  It all started with the philosopher Aristotle in 330 BC  Thought that all things are made up of one of four things Fire Earth Water Air

4. A brief history  It took a long time until someone looked at what made up everything on earth  In 1789 Antoine Lavoisier  Wrote the first extensive list of elements 33 elements in four categories  Distinguished between metals and non-metals, gasses, and acids producers

6. A brief history  In1828 Jons Jacob Berzelius developed a table for elements based on atomic weights.  Introduced letters to symbolize elements Example: H, O, etc.

7. A brief history  In 1864 John Newlands discovered that all of the known elements (there were <60) were arranged in order of atomic weights and observed similarities every 8 th element  He proposed the 'Law of Octaves'. This turned out to be incorrect

9. A brief history  Mendeleev  Considered the father of the modern periodic table  In 1869 he produced a table based on atomic weights but arranged 'periodically' with elements with similar properties under each other.  Gaps were left for elements that were unknown at that time and their properties predicted.

10. A brief history  He was able to used his table to predict the physical properties of three elements that were unknown at that time.  He stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong.  Problems arose when new elements were discovered and more accurate atomic weights determined

12. A brief history  In 1914 Henry Moseley was able to determine the atomic number of each of the known elements  Worked with He rearranged the elements in order of increasing atomic number.  X-Rays  He modified the 'Periodic Law’  Periodic Law: When elements are arranged in order of increasing atomic number, there is a regular pattern in their chemical and physical properties

13. A brief history  His research was stopped by the British government when is was forced to serve as a foot soldier in WWI.  He was killed in the fighting in Gallipoli by a sniper, at the age of 28.  Because of this loss, the British government restricted its scientists to noncombatant duties during WWII.

14. A brief history  Glenn Seaborg in 1944 created transuranic elements  There were 10 elements which he co-discovered  He moved 14 elements out of the main body of the periodic table below the Lanthanide series. These became known as the Actinide series.  These are the elements that are after uranium in the periodic table (atomic number >92)

15. A brief history  He is the only person to have an element named after him while still alive.  Seaborgium (Sg)- with atomic number 106  "This is the greatest honor ever bestowed upon me - even better, I think, than winning the Nobel Prize."  He died in 1999