I II III Ch. 6 - The Periodic Table & Periodic Law I. Development of the Modern Periodic Table (p. 174 - 181)
Mar 27, 2015
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