The Periodic Table
Unit II—Part 4
The Father of the Periodic Table—
Dimitri Mendeleev
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Mendeleev was the first scientist to notice
the relationship between the elements
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Arranged his periodic table by atomic mass
Said properties of unknown elements could be
predicted by the properties of elements around
the missing element
Moseley later discovered that the periodic
nature of the elements was associated with
atomic number, not atomic mass
The Periodic Table
Column = Group or
Family
18 columns on the
Periodic Table
Row = Period
7 rows on the
Periodic Table
What does the information in the
box tell me?
Atomic Number =
# of protons
Atomic Mass =
# of protons
plus neutrons
1
H
1.008
Elemental
Symbol
Metals, Nonmetals, and
Only
Semi-metals
Nonmetals are on the
nonmetal on the
metal side
Metals are to the
left of the
stair- step
Semi-metals,
“metalloids,”
touch the
stair-step
right of the stair-step
The Groups of the Periodic Table

Group 1: The Alkali Metals
Most reactive metals on the PT
 Rarely found free in nature
 Charge of 1—1 valence electron
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Group 2: The Alkaline Earth Metals
Still quite reactive
 Charge of 2—2 valence electrons
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T he Groups of the Periodic Table

Groups 3-12: Transition Metals
Found freely and in compounds in nature
 Charge is usually 2 but can vary—usually 2
valence electrons
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Group 13: Boron Family
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Charge is 3—3 valence electrons
The Groups of the Periodic Table

Group 14: The Carbon Family
Contains elements that can form unusual
bonds (carbon and silicon)
 Charge is +4 or -4—contains 4 valence
electrons
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Group 15: The Nitrogen Family
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Charge is -3—contains 5 valence electrons
The Groups of the Periodic Table
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Group 16: The Oxygen Family
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Group 17: The Halogens
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Also known as the chalcogens
Charge is -2—6 valence electrons
Most reactive nonmetals
charge is -1—7 valence electrons
Group 18: The Noble Gases (The Inert Gases)
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Nonreactive
Charge is 0—2 or 8 valence electrons
Special Rows on the PT
Lanthanides
Actinides