1. The Development of the Periodic Table

2. Drill
Please place your homework in the red bucket.

3. Objectives
iWBAT
Distinguish between groups on the periodic table (with respect to the group properties)

4.  Johann Dobereiner   (1829) Ca Cl Li Sr Br Na Ba I K
Johann Dobereiner proposed that nature contained triads of elements.
The middle element had properties that were an average of the other two elements when ordered (organized) by the atomic weight.
Dobereiner called this the “Law of Triads”.

5. J.A.R. Newlands (1866) J.A.R. Newlands developed the “Law of Octaves”.
Chemical elements were arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements.

6. Dmitri Mendeleev  (1869)
Dmitri Mendeleev listed the elements in columns in order of increasing atomic mass. Mendeleev then arranged the columns so that the elements with the most similar properties were side by side.

7. Mendeleev’s Periodic Table
Mendeleev left blank spaces in the table because there were no known elements with the appropriate properties and masses.

8. Ga Sc Ge Missing Elements Predicted By Mendeleev
Mendeleev, and others, were able to predict the physical and chemical properties of the missing elements.
Eventually these elements (Ga, Sc and Ge) were discovered and found to have properties similar to those elements Mendeleev predicted.

9.  Henry Moseley  (1913)
Moseley determined the atomic number of the atoms of the elements. He arranged the elements in a table by order of atomic number instead of atomic mass.
This is the current arrangement of the periodic table.

10. Henry Moseley later modified Mendeleev’s table by organizing the elements by atomic number rather than atomic mass.

11. Periodic Table Labeling
European notation
American system
IUPAC
(Inter. Union of Pure
& Applied Chemistry)
The elements in a group have similar properties because they have valence electrons in similar configurations
Roman numerals
IA, IIA, IIIA
1-18 (no letters)

12. Periodic Law The Periodic Law states: (textbook language)
The physical and chemical properties of the elements are periodic functions of their atomic numbers.
(In English)
When the elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals.

13. The Modern Periodic Table
The elements are listed in order of increasing atomic number from left to right and from top to bottom.

14. Electron Configurations
Write the electron configuration for:
Li, Na, K
Be, Mg, Ca
Ne, Ar, Kr

15. Electron Configurations
What do you see that is similar about each of the electron configurations in the group?

16. Electron Configurations
Write the electron configuration for elements in the following groups:
Be, Mg, Ca
Ne, Ar, Kr

17. 1s1
1s22s1
1s22s22p63s1
1s22s22p63s23p64s1
1s22s22p63s23p64s23d104p65s1
1s22s22p63s23p64s23d104p65s24d10 5p66s1
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s1 H 1 Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87
Do you notice any similarity in these configurations of the alkali metals?

18. Valence Electrons
Explain how similar electron configurations and valence electrons tie together.

20. Stable Octet
Elements want to gain, or lose, electrons to have 8 valence electrons
(or you can say a stable octet, or full octet)

21. Groups vs Periods On the Periodic Table:
Groups are also called columns or families
Periods are rows

22. Things to know about the Periodic Table:
Main/representative group elements
Group Names (alkali metal, alkaline earth metal, transition metal, halogens, noble gases, lanthanides, actinides)
Solid, liquid, or gas
Metal, non-metal, metalloid
Valence electrons

23. Main/Representative Groups (Groups # 1, 2, 13-18…i.e. s & p)

26. Blue = metal Yellow = non-metal
Pink = metalloid or semi-metal

27. Elements in the 1A-7A groups are called the representative elements
outer s or p filling 1A 8A 2A 3A 4A 5A 6A 7A

28. Properties of Groups Alkali metals Silvery appearance
Soft enough to be cut with a knife
Extremely reactive with air and water
Stored in oil (or kerosene)
Alkali metals are not found in nature as free elements

29. Properties of Groups Alkaline earth metals
Extremely reactive with water
Alkaline earth metals are not found in nature as free elements
Group 2 metals are
harder, denser and stronger and have higher melting and boiling points than alkali metals.

30. Properties of Groups Halogens Very high electronegativities
Seven valence electrons (one short of a stable octet)
Highly reactive, especially with alkali metals and alkaline earths

31. Properties of Groups Noble Gases
He, Ne and Ar do not react with any other element.

32. Properties of Specific Element Groups
D block elements
Commonly called Transition metals
Good conductors of electricity
High luster

33. Properties of Specific Element Groups
p block elements
Contains metals, non-metals and semi-metals

34. Properties of Specific Element Groups
f block elements
Inner Transition metals
Called Lanthanides and Actinides
Actinides
are all radioactive
the first four elements are found naturally and the remaining actinides are man-made.