I II III

Ch. 6 - The Periodic Table & Periodic Law

I. Development of the Modern Periodic Table(p. 174 - 181)

A. Mendeleev

Dmitri Mendeleev (1869, Russian) Organized elements

by increasing atomic mass

Elements with similar properties were grouped together

There were some discrepancies

A. Mendeleev

Dmitri Mendeleev (1869, Russian) Predicted properties of undiscovered

elements

B. Moseley

Henry Moseley (1913, British)

Organized elements by increasing atomic number

Resolved discrepancies in Mendeleev’s arrangement

This is the way the periodic table is arranged today!

C. Modern Periodic Table

1

2

3

4 5

6

7

Group (Family)Period

1. Groups/Families

Vertical columns of periodic table

Numbered 1 to 18 from left to right

Each group contains elements with similar chemical properties

2. Periods

Horizontal rows of periodic table

Periods are numbered top to bottom from 1 to 7

Elements in same period have similarities in energy levels, but not properties

Main Group ElementsTransition MetalsInner Transition Metals

3. Blocks

3. Blocks

1

2

3

4

5

6

7

Lanthanides - part of period 6

Actinides - part of period 7

Overall Configuration

I II III

II. Classification of theElements

(pages 182-186)

Ch. 6 - The Periodic Table

A. Metallic Character

1

2

3

4

5

6

7

MetalsNonmetalsMetalloids

1. Metals

Good conductors of heat and electricityFound in Groups 1 & 2, middle of table in

3-12 and some on right side of tableHave luster, are ductile and malleable

a. Alkali Metals

Group 11 Valence electronVery reactiveElectron configuration

ns1

Form 1+ ionsCations

Examples: Li, Na, K

b. Alkaline Earth Metals

Group 2Reactive (not as reactive as alkali metals)Electron Configuration

ns2

Form 2+ ionsCations

Examples: Be, Mg, Ca, etc

c. Transition Metals

Groups 3 - 12Reactive (not as reactive as Groups 1 or

2), can be free elementsElectron Configuration

ns2(n-1)dxwhere x is column in d-blockForm variable valence state ionsCations

Examples: Co, Fe, Pt, etc

2. Nonmetals

Not good conductorsFound on right side of periodic table –

AND hydrogenUsually brittle solids or gases

a. Halogens

Group 17 (7A)Very reactiveElectron configuration

ns2np5

Form 1- ions – 1 electron short of noble gas configuration

Anions Examples: F, Cl, Br, etc

b. Noble Gases

Group 18Unreactive, inert, “noble”, stableElectron configuration

ns2np6 full energy levelHave a 0 charge, no ionsExamples: He, Ne, Ar, Kr, etc

3. Metalloids

Sometimes called semiconductorsForm the “stairstep” between metals and

nonmetalsHave properties of both metals and

nonmetalsExamples: B, Si, Sb, Te, As, Ge, Po, At

B. Chemical Reactivity

Alkali MetalsAlkaline Earth MetalsTransition MetalsHalogensNoble Gases

C. Valence Electrons

Valence Electrons

e- in the outermost energy level

Group #A = # of valence e- (except He)1A

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

8A

C. Valence ElectronsValence electrons =

electrons in outermost energy levelYou can use the Periodic Table to

determine the number of valence electronsEach group has the same number of

valence electrons1A

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

8A

D. Lewis Diagrams

Also called electron dot diagramsDots represent the valence e-

Ex: Sodium Ex: Chlorine

Lewis Diagram for Oxygen