1. Periodic Table History

2. Aristotle 4 Elements Fire, Water, Air, Earth
~350 B.C.-
Aristotle 4 Elements Fire, Water, Air, Earth

3. By
14 elements were known

4. Antoine Lavoisier wrote the first extensive list of 33 elements.
~1789-
Antoine Lavoisier wrote the first extensive list of 33 elements.

5. 1829 -
Johann Dobereiner (German Chemist) noticed that Br, Cl, and I had similar properties and that Br’s atomic mass was between that of Cl & I. He found three other groups with similarities. He called these groups triads.

6. Other Triads of Dobereiner:
Cl, Br, I
Ca, Sr , Ba
S, Se, Te
Li, Na, K

7. 1864 -
John Newlands (English Chemist) arranged the now known 62 elements from lightest to heaviest. He also noticed that every 8th element had similar chemical and physical properties. Their properties were repeating. This became known as Newland’s Law of Octaves. Li Be B C N O F Na Mg Al Si P S Cl

8. 1869 -
Dmitri Mendeleev (Russian Chemist) organized the elements by atomic mass and made it into table form to help his students. Elements with similar properties were put into the same column.

9. Mendeleev (cont.) He left blanks where elements seemed to be missing.
He was considered the father of the Modern Periodic Table.
There were places where heavier elements were put before lighter elements because of their properties:
Te – I Co – Ni Ar – K
(He felt the mistake was in measuring the mass and this would be corrected with further research.)

10. The Periodic Table
Dmitri Mendeleev ( )

11. 1913 -
Henry Moseley (English Chemist) arranged elements by atomic number. This gave rise to a New Periodic Law, “Properties of elements are periodic functions of their atomic number.”

12. Glenn Seaborg (1912-1999) Discovered 8 new elements.
Only living person for whom an element was named.

13. Periodic Table Terminology
Period/Series = horizontal rows 
Group/Family = vertical columns

14. Metals Located to the left of the staircase line Characteristics
Lose electrons to form + ions (cations)
Shiny
Metallic luster (silver or grayish white)
Malleable
Good conductors
react with acid
Most metallic element = Fr (francium)

15. Nonmetals Located to the right of the staircase line Characteristics:
Tend to gain electrons to form – ions (anions)
Dull
Poor conductors
Good insulators
Brittle
Most reactive nonmetal = F (fluorine)

16. Metalloids Located on and below the staircase line except At and Al.
Characteristics:
Tend to gain or lose electrons
Shiny and dull
Good and poor conductors
Malleable and brittle

17. Where are Periods, Groups, Metals, Nonmetals, and Metalloids?