1. Chapter 5
The Periodic Law
West Valley High School
Chemistry
Mr. Mata

2. Standard 1C
How to use the Periodic Table to identify specific groups and trends for specific traits.

3. Essential Question
How is the Periodic Table of Elements arranged to be a useful tool in chemistry?

4. 5-1 History of the Periodic Table
Cannizzaro ( ) developed a method for measuring atomic masses.
Stanislao Cannizzaro

5. Mendeleev (1834-1907) Created the 1st periodic table based on increasing atomic mass.
Dmitri Mendeleev

6. Moseley (1887-1915) set up the periodic table according by increasing atomic number.
Henry Moseley

7. Periodic = repeating pattern.
Ex: days of week, months of year, seasons, ocean waves, life cycles.
Periodic Table of Elements - refers to properties of elements that repeat on each row (period).
Contains 7 periods.

8. Periodic law: chemical & physical properties of elements are periodic functions of atomic #’s.
When elements are arranged in order of increasing atomic #, a periodic repetition of their properties occurs.

9. Periodic table: arrangement of elements in order of their atomic numbers.
elements with similar properties are in the same family (group).

10. Group 1 (Alkali Metals) combine vigorously with many nonmetals.
very reactive.
not found in nature as free elements.
Ex: Li, Na, K

11. Group 2 (Alkaline-Earth Metals)
harder, denser, stronger, higher melting points than group 1.
not found in nature as free elements.
Ex: Mg, Ca, Sr

12. Groups 3-12 (Transition metals) Very colorful. Metallic properties.
Copper
Iron
Groups (Transition metals)
Very colorful.
Metallic properties.
Chromium
Cobalt

13. Most synthetically produced in labs.
Cerium
Lanthanides
“rare earth” elements.
Shiny, reactive, metals.
Actinides
Unstable; reactive.
Most synthetically produced in labs.

14. Modern Periodic Table Glenn Seaborg (1912 – 1999).
Discovered several transuranium elements.
1951 Nobel Prize in Chemistry.
Element 106 (Sg) Seaborgium named in his honor.

15. Seaborg placed actinides below lanthanides
These elements are sometimes placed beneath the rest of the table.
Why???? …….to save space on table.
allowed prediction of properties of newly-discovered actinides based on properties of lanthanides.

16. Let’s Compare! Nonmetals Solids, liquids & gases at RT Metals
Solids are brittle and dull
Poor conductors of heat & elect.
Metalloids
Properties of metals & nonmetals
Mostly brittle solids
Intermed. conductors of elect. - aka semi -conductors
Metals
Good conductors of heat & elect.
Malleable
Ductile
Luster
Solids at RT