1. History of the Periodic Table

2. John Newland – Law of Octaves

3. Dmitri Mendeleev 1869 – only 63 known elements
Ranked elements by atomic mass (generally)

4. Dmitri Mendeleev Predicted the existence and properties of elements
PREDICTED ACTUAL

5. Lord Rayleigh – Noble Gases
1895 – first noble gas discovered.
Argon – nonreactive. Placed at the end of the table.
He Ne Kr Ar Xe

6. Noble Gases Non-reactive because they have EIGHT valence electrons
REMEMBER: VALENCE electrons are the electrons in the outermost shell that determine an element’s reactivity.

7. Elements and compounds WANT to have a full outer electron shell.
Octet Rule
The octet rule states that elements gain or lose electrons until they have an electron configuration like the nearest noble gas.
Elements and compounds WANT to have a full outer electron shell.

8. Glenn Seaborg Last change to the periodic table
1940 – discovered plutonium and all elements from 94 to 102
Moved the Actinide and Lanthanide series beneath the table

9. Modern Table Arranged by atomic number:
Increasing number of protons (and therefore electrons in neutral atoms).
Contains Periods and Groups

10. Periodicity
A pattern that repeats – in this case, repeating properties of elements
Periods are HORIZONAL rows
Period 1 
Period 2 
Period 3 
Period 4 
Period 5 
Period 6 
Period 7 

11. Groups The vertical columns of the periodic table
Also called “Families”

12. Groups Elements in groups share similar properties
We’ll get into the details of this later. 

13. Write down any questions that you have about the periodic table.
Exit Slip
Write down any questions that you have about the periodic table.