1. Chapter 6
The Periodic Table

2. History of the Periodic Table
In the early 1700s, only 13 elements were known (gold, silver, copper, other common metals)
By 1829, significantly more elements had been found
1829 – Johann Doberiner used triads to sort similar elements

3. History of the Periodic Table
Dimitri Mendeleev “Father of the Periodic Table”
-Made the first accepted Periodic Table
-Noticed trends and left empty spaces for “missing” elements
-Sorted elements by atomic mass

4. Mendeleev’s Periodic Table
Arranging the elements this way created gaps in his periodic table
How did Mendeleev arrange the elements in his periodic table?

5. Try predicting the names and masses of the unknown elementsSc
45.0 Ga
69.7 Ge
72.6 Tc
97.9 Hf
178.5 Re
186.2 Po
209 At
210

6. Henry Moseley 1913
– Found a method to determine atomic number (# of protons).
--Rearranged the PT so elements were arranged by increasing atomic number

7. Modern Periodic Table
The Modern Periodic Table is arranged by atomic numbers so elements with similar properties fall in the same columns
Periodic Law- Properties of elements are based on atomic number and valence electrons

8. Periods – 1-7, run across the periodic table
Organization of the Periodic Table
Periods – 1-7, run across the periodic table

9. Groups – 1-18, run vertically (up and down) in the periodic table
Organization of the Periodic Table
Groups – 1-18, run vertically (up and down) in the periodic table

10. Classes of Elements 3 Classes Metals – located on left of PT
Nonmetals – Located on right of PT
Metalloids – Located along the “staircase”

11. Metals

12. Properties of Metals Good conductors Luster (shiny)
Solid at room temperature
Ductile (can be drawn into wires)
Malleable (can be hammered into sheets)
Magnetic
Form alloys
High density
Lose electrons (form cations)

13. Nonmetals
Brittle
Non­conductors dull

14. Properties of Nonmetals
Poor conductors (nonconductors)
Dull (not shiny)
Most are Liquid or gas at room temperature
Brittle
Low density
Gain electrons (form anions)

15. Metalloids
Properties of both metals and nonmetals

16. Properties of Metalloids
Semi conductors
Dull (not shiny)
Solids at room temperature
Used in computers
Have a mixture of metallic and nonmetallic properties

18. Some elements that are as gases at room temperature cannot exist as a single atom, but must exist as a diatomic molecule.
N2, H2, O2, Cl2, F2
Copy these diatomic elements

19. A Look at the Bohr Model for electron configurations
1913- Niels Bohr
- Young Danish physicist who developed a new atomic model
- Changed Rutherford’s model to include energy levels for electrons
- Proposed that an electron is found only in specific circular paths (or orbits) around the nucleus
- Known as the “planetary model”

20. A Look at the Bohr Model for electron configurations
Valence Electrons – Electrons in the outer “shell”
8e-
8e-
2e-
Octet Rule – an atom is most stable when it has 8 electrons in its outer (valence) shell. It will gain or lose electrons to reach an octet. “2 will do but 8 is great”

21. Let’s draw some examples:

22. Energy Levels (rings) and the PT
Energy levels correspond to periods or rows on the periodic table

23. Families of the Periodic Table (Groups)
Group 1: Alkali metals
Group 2: Alkali Earth Metals
Groups 3-12: Transition Metals
Group 17: Halogens
Group 18: Noble Gases
Inner Transition Metals – “cut out” below periodic table

24. Families on the Periodic Table
-Group 1 = Alkali Metals
Soft
Extremely reactive
(but…Hydrogen is NOT a metal)
1 valence electron
Form an ion with +1 charge
Video

25. Families on the Periodic Table
Group 2 = Alkali-Earth Metals
Not as soft as Group 1, but still somewhat soft
Reactive, but less than Group 1
2 valence electrons
Form ion with +2 charge
Video

26. Families on the Periodic Table
-Groups =
Properties vary greatly
(due to “steps”)
Valence Electrons= Group # - 10
May form cation or anion (depending on group)
Example:
Group 18 – 10 = 8 valence
electrons

27. Families on the Periodic Table
-Group 17 = Halogens
Very reactive
7 valence electrons
Form ion with -1 charge

28. Families on the Periodic Table
-Group 18 = Noble Gases
Very unreactive
Many used in creating signs
When gas is heated it glows
8 valence electrons
They have a stable (full) valence octet

29. Blocks on the Periodic Table
Groups 3-12 =
Transition Metals
Luster, conductive, Malleable, Ductile
Hg is the ONLY liquid metal
examples:

30. Blocks on the Periodic Table
Lanthanides
Actinides
INNER Transition metals
Formerly called Rare Earth Metals, then changed
to Lanthanides and Actinides. Now called
Inner Transition Metals
“Cut Out” located below the Periodic Table