2.7 an introduction to the periodic table
TRANSCRIPT
2.7 An Introduction to the Periodic
Table
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Periodic TableDmitri Mendeleev (1834-1907)
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Groups and Periods
On the periodic table,• elements are arranged according to similar
properties.
• groups contain elements with similar properties in vertical columns.
• periods are horizontal rows of elements.
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Groups and Periods
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Group Numbers
Group Numbers• use the letter A for the representative elements (1A to
8A) and the letter B for the transition elements.
• also use numbers 1-18 to the columns from left to right.
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Names of Some Representative Elements
Several groups of representative elements are known by common names.
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Alkali Metals
Group 1A(1), the alkali metals, includes lithium, sodium, and potassium.
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Halogens
Group 7A(17) the halogens, includes chlorine, bromine, and iodine.
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Identify the element described by the following.
A. Group 7A(17), Period 41) Br 2) Cl 3) Mn
B. Group 2A(2), Period 31) beryllium 2) boron 3) magnesium
C. Group 5A(15), Period 21) phosphorus 2) arsenic 3) nitrogen
Learning Check
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A. Group 7A (17), Period 41) Br
B. Group 2A (2), Period 33) magnesium
C. Group 5A(15), Period 2
3) nitrogen
Solution
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Metals, Nonmetals, and Metalloids
The heavy zigzag line separates metals and nonmetals.• Metals are located to
the left.• Nonmetals are located
to the right. • Metalloids are located
along the heavy zigzag line between the metals and nonmetals.
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Metals• are shiny and ductile.• are good conductors of heat and electricity.
Nonmetals• are dull, brittle, and poor conductors.• are good insulators.
Metalloids• are better conductors than nonmetals, but not
as good as metals.• are used as semiconductors and insulators.
Properties of Metals, Nonmetals, and Metalloids
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Comparing a Metal, Metalloid, and Nonmetal
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Identify each of the following elements as 1) metal 2) nonmetal 3) metalloid
A. sodium ____B. chlorine ____C. silicon ____D. iron ____E. carbon ____
Learning Check
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Identify each of the following elements as 1) metal 2) nonmetal 3) metalloid
A. sodium 1 metalB. chlorine 2 nonmetalC. silicon 3 metalloidD. iron 1 metal E. carbon 2 nonmetal
Solution
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Metals Tend to Lose Electrons
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Nonmetals Tend to Gain Electrons