1. Groups of the Table and A Brief History
The Periodic Table
Groups of the Table and A Brief History

2. The Father of the Periodic Table—Dmitri Mendeleev
Mendeleev ( ) was the first scientist to notice a relationship between the elements
Around 1865 he arranged his periodic table by atomic mass
Said properties of unknown elements could be predicted by the properties of elements around the missing element

3. Dmitri Mendeleev

4. The Periodic Table
Henry Moseley ( ) later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass.

5. The Periodic Table Column = Group or Family
18 columns on the Periodic Table
Row = Period
7 rows on the Periodic Table

6. What does the information in the box tell me?1 H
1.008
Atomic Number = # of protons and # of electrons
Elemental Symbol
Atomic Mass = # of protons plus neutrons

7. Metals, Nonmetals, and Metalloids
Hydrogen (H) the only
nonmetal on the metal side
Nonmetals are on the right of the stair-step
Metals are to the left of the stair- step
Semi-metals,
“metalloids,”
touch the stair-step

8. VALANCE ELECTRONS
The electrons that are in the outermost energy level of any atom. Examples:
Hydrogen has 1 valance electron
Boron has 3 valance electrons
Oxygen has 6 valance electrons
Argon has 8 valance electrons

9. 8 VALANCE ELECTRONS
In order to feel and be stable, all atoms would like to have 8 valance electrons. If they don’t already have 8 they will react very well and bond with others that can add up to 8. Example: Oxygen has 6 valance electrons and reacts very easily with 2 Hydrogen atoms to form H2O, water.

10. The Groups of the Periodic Table
Group 1 or 1a: The Alkali Metals
Most reactive metals on the PT
Rarely found free in nature
Charge of +1, 1 valence electron

11. Group 2 or 2a: The Alkaline Earth Metals
Still quite reactive
Charge of +2, 2 valence electrons

12. T he Groups of the Periodic Table
Groups 3-12 or 3-12b: Transition Metals
Found freely and in compounds in nature
Charge is usually +2 but can vary—usually 2 valence electrons

13. Group 13 or 3a: Boron Family
Charge is +3, 3 valence electrons

14. The Groups of the Periodic Table
Group 14 or 4a: The Carbon Family
Contains elements that can form unusual bonds (carbon and silicon)
Charge is +4 or -4, contains 4 valence electrons

15. Group 15 or 5a: The Nitrogen Family
Charge is -3, contains 5 valence electrons

16. The Groups of the Periodic Table
Group 16 or 6a: The Oxygen Family
Also known as the chalcogens
Charge is -2, 6 valence electrons

17. Group 17 or 7a: The Halogens
Most reactive nonmetals
charge is -1, 7 valence electrons

18. Group 18 or 8a: The Noble Gases (The Inert Gases)
Inert means Nonreactive, don’t normally react with other elements
Charge is 0, 2 or 8 valence electrons

19. Special Rows on the PT
Lanthanides
We call these rare earth metals because they are rarely found on earth.
Actinides