1. The Periodic Table
Of Elements

2. Development of the Modern Periodic Table
Objectives
Trace the development and identify key features of the periodic table
Identify specific groups within the periodic table

4. Organizing by Properties
1869 – Dmitri Mendeleev organized known elements into chart (rows and columns)
According to atomic mass
Similar to putting together a large puzzle
Predicted new elements would be discovered with certain properties

6. Arranging by Atomic Number
Many discrepancies with Mendeleev’s table
Moseley arranged by increasing atomic number rather than atomic mass
Discrepancies disappeared

7. Periodic Law
The properties of the elements repeat periodically when the elements are arranged in increasing order by their atomic number.

8. Modern Periodic Table

9. First Ionization Energy
The energy required to remove one electron from an atom in a gaseous phase

10. Periodic Table Today Vertical column = group or family
Horizontal row = period
Check out periodic table on wall

11. Chemical Families
1A = alkali metals (react with water to form alkaline, or basic, solution
2Na(s) + 2H2O(l) = 2NaOH(aq) + H2(g) + heat energy
2A = alkaline earth metals also react with water
7A = halogens (salt formers)\
1A-8A = representative metals
Bgroup (2A-3A) = transition metals
Two bottom rows = inner transition metals (lanthanides and actinides)

12. Periods
7th period incomplete – fewer than half occur naturally on earth and all are radioactive

13. Classification Cont. Metals – to the left of the staircase
Properties: generally shiny when smooth and clean, solid at room temperature, good conductors of heat and electricity
Nonmetals – to the right of the staircase
Properties: generally gases or brittle, dull-looking solids. Poor conductors of heat and electricity
Metalloids – bordering staircase
Si and Ge are most important for use in semiconductors

15. Homework 6.1 assessment P.174 # 26-40
Quarter extra credit (25 points exam)
Develop a periodic table (must be large on posterboard) expressing periodicity in an interest you may have

16. Activity
In the cards periodic table activity