1. The Periodic Table
Chapter 5

2. Organizing the Elements
5.1

3. Organizing Elements Game
How did you arrange the table?
Based on your arrangement, where would you put a card for an element that is a liquid with an atomic mass between 9 and 13? What would its atomic mass actually be?

4. Historic Overview Article
Trace the evolution of the current Periodic Table by creating a detailed timeline.
Show important steps in the history of arranging elements in meaningful ways. Include every step that is listed in the article!
Describe the basic tenets of each model for arranging elements

5. Questions What is the periodic law? What is an outlier?
What element did Mendeleev start his “game of cards” with? Why did he pick this element (in other words, why not hydrogen or helium?)
Why did Mendeleev leave spaces on his version of the periodic table?

6. More Questions What does interpolated mean?
What element is named after Mendeleev? What is its atomic number? How many protons does it have?

7. Dmitri Mendeleev

8. Search for Order Brings order to seemingly unrelated facts
Helped chemists predict the existence of elements that weren’t discovered yet
Groups elements according to their chemical and physical properties

9. Dmitri Mendeleev
Thought of a way to approach the problem of organizing the elements while playing solitaire
Mendeleev made playing cards of the elements that included the mass and properties of the elements, then arranged them in order of increasing mass

10. Mendeleev’s Periodic Table
Strategy for organization: What did he look at?
chemical properties
physical properties
atomic mass
density
color
melting point
Valence electrons

11. Mendeleev’s Proposal
Elements arranged in rows based on increasing mass.
Elements with similar properties are in same column.
Chart was a Periodic Table
arrangement of elements in columns based on a set of properties that repeat.

12. Mendeleev’s Prediction
Table incomplete– elements not yet discovered
Left spaces in table for undiscovered elements

14. Evidence Supporting Mendeleev’s Table
Close match between Mendeleev’s predictions and the actual properties of new elements showed how useful table was.
Ex. Discovery of: Aluminum, Gallium, Scandium, and Germanium

15. The Modern Periodic Table
5.2

16. The Periodic Law Elements are arranged by increasing atomic number
Periods
Rows of the periodic table
The period number tells us how many energy levels an atom of a particular element will have
Groups (or Families)
Columns of the periodic table
Properties of elements repeat in a predictable way when atomic numbers are used to arrange elements into groups
Elements in vertical groups have similar electron configurations, which determines the chemical properties of an element

17. Periodic Law
The pattern of repeating chemical and physical properties that exists in groups of the periodic table

18. Atomic Weight (or Atomic Mass)
A value that depends on the distribution of an element’s isotopes in nature and the masses of those isotopes.

19. Calculating Atomic Weight
In nature, most elements exist as a mixture of two or more isotopes.
Example: There are two natural isotopes of Chlorine that
Chlorine – 35
Chlorine – 37
How are these different?

20. Distribution of Chlorine Atoms in Nature
Weighted Averages
Some isotopes occur more frequently in nature than do other isotopes
Distribution of Chlorine Atoms in Nature
Isotope
Percentage
Atomic Mass
Chlorine-35
75.78%
34.969
Chlorine – 37
24.22%
36.966

21. Classifying Elements Can be classified in three ways:
By state of mater at room temperature (solid, liquid or gas)
By those that occur naturally and those that do not
Based on their general properties we can divide them into METALS, NONMETALS & METALLOIDS
Periodic Table Coloring Activity
With a marker, draw solid lines around the following elements
B, Si, Ge, As, Sb, Te, Po, At

22. Trends in the PT
Across a period from left to right, the elements become less metallic and more non-metallic in their properties
The most reactive metals are on the left side of the PT
The most reactive non-metals are in Group 17
Complete Side 1 of Element Classification Graphic Organizer

23. Valence Electrons
An electron that is in the highest occupied energy level of an atom
Elements in a group have similar properties because they have the same number of valence electrons
We can illustrate valence electrons using electron dot diagrams
Valence electrons are the electrons that participate in bonding between atoms

24. Electron Dot Diagram

25. How do we find the number of valence electrons?
Look at the Group number!
The group number tells you how many electrons are in the outer shell of an atom
Group 1 – 1 valence electron
Group 2 – 2 valence electrons
Group 13 – 3 valence electrons
Group 14 – 4 valence electrons
Group 15 – 5 valence electrons

26. Making Dot Diagrams Write down the chemical symbol of the element
Determine the number of valence electrons
Use a dot to represent each valence electron by drawing dots around the chemical symbol
Pretend there is a box around the chemical symbol, putting single electrons on the edges of the box. After you have put a single dot on each edge, then start paring up dots with any remaining electrons.

27. Example - Carbon C

28. Valence Electron Practice

29. Dot Diagram Game 4 Teams Racing to make correct dot diagrams
Winning Team gets a HW pass for ONE HW assignment
Everyone on your team MUST participate