Ch. 5 - The Periodic Table

I. History of the Periodic TableMendeleev

Mosely

Periodic Law

A. Dmitri Mendeleev

Dmitri Mendeleev (1869, Russian)

• Organized elements by

increasing atomic mass.

• Predicted the existence of

undiscovered elements.

B. Henry Mosely

Henry Mosely (1913, British)

• Organized elements by

increasing atomic number.

• Fixed problems in Mendeleev’s

arrangement.

Properties of elements repeat in a predictable way when atomic numbers are used to arrange elements into groups.

C. Periodic Law

Key Concept

How is the modern periodic table organized?

In the modern periodic table, elements are arranged by increasing number of protons.

Ch. 5 - The Periodic Table

II. OrganizationMetallic Character

Rows & Columns

Table Sections

A. Metallic Character

1

2

3

4 5

6

7

Metals Nonmetals Metalloids

A. Metallic Character

The majority of the elements on the periodic table are classified as metals.

• Metals are elements that are good conductors of electric current and heat.

• Except for mercury, metals are solid at room temperature.

• Most metals are solids. • Many metals are ductile;

that is, they can be bent.

A. Metallic Character

Nonmetals generally have properties opposite to those of metals.

• Nonmetals are elements that are poor conductors of heat and electric current.

• Nonmetals have low boiling points – many nonmetals are gases at room temperature.

• Nonmetals that are solids at room temperature tend to be brittle. If they are hit with a hammer, they shatter or crumble.

A. Metallic Character

Metalloid elements are located on the periodic table between metals and nonmetals.

• Metalloids are elements with properties that fall between those of metals and nonmetals.

• For example, a metalloid’s ability to conduct electric current varies with temperature. Silicon (Si) and Germanium (Ge) are good insulators at low temperatures and good conductors at high temperatures.

B. Rows and Columns

1

2

3

4

5

6

7

Representative Elements Transition Metals

B. Rows and Columns

1

2

3

4 5

6

7

Group (Family) Period

Each column in the periodic table is called a Group or Family.

• The elements in a group have the same number of valence electrons, so members of the same group in the periodic table have similar chemical properties.

• This pattern of repeating properties is the periodic law.

B. Rows and Columns

Each column in the periodic table of elements is a Group.Elements in group 1 have _1_ valence electron.Elements in group 2 have _2_ valence electrons.Elements in group 13 have _3_ valence electrons.Elements in group 14 have _4_ valence electrons.Elements in group 15 have _5_ valence electrons.Elements in group 16 have _6_ valence electrons.Elements in group 17 have _7_ valence electrons.Elements in group 18 have _8_ valence electrons.

B. Rows and Columns

Each row in the table of elements is a Period.• Elements in period _1_ have one energy level.• Elements in period _2_ have two energy levels.• Elements in period _3_ have three energy levels.• Elements in period _4_ have four energy levels.• Elements in period _5_ have five energy levels.• Elements in period _6_ have six energy levels.• Elements in period _7_ have seven energy levels.

Horizontally Into Periods

B. Rows and Columns

The Periodic Table

III. Periodic TrendsTerms

Dot Diagrams

There are four pieces of information for each element.

1. _______________

2. _______________

3. _______________

4. ______________

Review

Periodic Law

• Properties of elements repeat

periodically when the elements

are arranged by increasing

atomic number.

A. Terms

A. Terms

Valence Electrons

• e- in the outermost energy level

A. Terms Group # = # of valence e- (except He)

• Families have similar chemical characteristics. Period # = # of energy levels

1A

2A 3A 4A 5A 6A 7A

8A

B. Dot Diagrams

Dots represent the valence e-. Ex.: Sodium Ex.: Chlorine