1. 5.2 The Periodic Table

2. Organizing the periodic table…
Timeline of Element Discoveries
By 1750 there were only 17 elements identified
In 1860 Dmitri Mendeleev, Russian chemist, organized the elements in rows of increasing mass number so that elements with similar properties were in the same column

3. Organizing the Periodic Table…
Mendeleev noticed holes in his periodic table and predicted the holes would be filled as more elements were discovered.
Mendeleev could also predict the properties of these missing elements because his periodic table arranged elements with the same properties together.

4. Mendeleev

6. Modern Periodic Law
The Periodic table is arranged with increasing atomic number (number of protons).
Periods – a row on the periodic table
Groups or Families – a column on the periodic table

9. Periods Families The periodic table has _______ periods.
Elements in similar groups or families have similar properties
This pattern of the periodic properties is called the periodic law

10. Atomic Weight
Atomic Weight – the average mass of all the isotopes found in nature.

11. Classes of Elements Metals Left side of the periodic table
Good conductors
Mostly solid at room temp
Most are malleable and ductile
Most are reactive

14. Classes of Elements Nonmetals Right side of the periodic table
Poor conductors
Most are gases and liquids at room temperature
Can be very reactive or very unreactive

17. Classes of Elements Metalloids
Elements with properties that are in between metals and nonmetals
Germanium
Boron
Silicon
Antimony
Tellurium

18. Label Your Periodic Table!
Include, Periods, Groups, Metals, Nonmetals, Metalloids