The History of: The Periodic Table Writing Piece How is a department store/grocery store organized? Why is it important to you that it is organized? Look at the periodic table, what are some of the organizations do you see?

Why is the Periodic Table important? The periodic table is the most useful tool to a chemist. You get to use it on every test in chemistry. It organizes lots of information about all the known elements.

Pre-Periodic Table Chemistry … …was a mess!!! No organization of elements. Imagine going to a library with no organization!! Difficult to find information. Chemistry didn’t make sense. Dmitri Mendeleev – about 1869 he started organizing the periodic table based on previous scientists work

Dmitri Mendeleev: Father of the Table HOW HIS WORKED… Put elements in rows by increasing atomic mass. Put elements in columns by the way they reacted. Didn’t work. There were some problems. SOME PROBLEMS… He left blank spaces for what he said were undiscovered elements. (Turned out he was right!) He broke the pattern of increasing atomic mass to keep similar reacting elements together. So Grouping them by increasing mass did not work.

The Current Periodic Table Mendeleev wasn’t too far off. Now the elements are put in rows by increasing ATOMIC NUMBER!! The horizontal rows are called periods and are labeled from 1 to 7. The vertical columns are called groups are labeled from 1 to 18.

The Current Periodic Table And because of this The medals are grouped together The non-metals are grouped together The metalloids are grouped together Nobel gases (non-metals) are grouped together Elements with similar properties are grouped together (based on their valence electrons-out most shell electrons)

Pattern Once you know the pattern you can do it! Define the following Periods Groups/Families Metals Non-metals Metalloids Nobel Gases

Time Line Use your time line and write down a scientist other than Mendeleev that contributed to the periodic table.