1. Organizing the Elements
The Periodic Table
Organizing the Elements

2. Dmitry Mendeleev
( )
First person to construct a periodic table.
Mendeleev listed the elements in order of increasing atomic mass.
Also, elements with similar properties were put in the same column.

3. Mendeleev
He left blank spaces in table.
He was able to predict the physical and chemical properties of the missing elements.

4. Henry Moseley
( )
Determine the atomic number of the atoms of the elements.
Moseley arranged the elements in (1913) a table by order of atomic number instead of atomic mass.
This is the way the periodic table is arranged today.

5. The Modern Periodic Table
How is it organized?
Element is identified by its symbol in the center.
The Atomic Number is centered above the symbol.
The Atomic Mass and the name is below the symbol.

6. How it is organized?
Atomic Number Na
Sodium
Atomic Mass

7. The periodic table is organized by groups and periods.
Groups or families are the vertical columns of the table.
Periods are the horizontal rows of the table.

8. The Periodic law
When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.
Elements that have similar chemical and physical properties end up in the same column in the periodic table

9. Groups or Family (vertical columns)
Sample test question.
Elements in any group of the periodic table have similar physical and chemical properties.
Which of the following elements have similar properties as Ca?
a) Sc b) K c) Mg d) S

10. Different Groups in the Periodic Table
The Metals
High electric conductivity.
High luster when clean.
Ductile
Malleable.
The alkali Metals
The Group 1A elements.
H is the exception. Not a metal.
The alkaline Earth Metals
The Group 2A
The Transition Metals
The Group B

11. Different Groups in the Periodic Table
The Nonmetals
Nonlustrous
Poor conductors of electricity
The Halogens
The nonmetals of Group 7A
The Noble Gases
Group 0 or Group 8A
Also called inert gases
Few chemical reactions

12. Different Groups in the Periodic Table
The Metalloids
Most of the elements that border the heavy stair-step line.
Have properties that are intermediate between the metals and nonmetals.
They are the semiconductors used in computers. (Si and Ge)
The Nonmetals

13. Lanthanides and Actinides
Lanthanides series
Actinides
Located in the f block series.
Silvery-white metals
Relative soft metals
High melting and boiling points
Very reactive
Also located in the f block series.
All are radioactive
Very dense metals