19.3 – Periodic Table
Objectives – LT#8-13
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Use the periodic table to obtain information.
Describe the arrangement of the periodic table.
Explain how groups on the periodic table were
determined and what similarities exist between elements
in the same group.
Relate the location on the periodic table to the number of
energy levels in an element.
Explain the importance of a full valence shell and how
that is achieved by noble gases
Explain what metals, nonmetals and semi-metals are
and where they are located on the periodic table.
Organization of Elements
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Dmitri Mendeleev
Discovered pattern (periodic)
when he arranged elements in
order of increasing atomic
mass
Mendeleev made predictions
and left blanks in his periodic
table as he lined up elements
by chemical properties
http://www.cartage.org.lb/en/themes/sciences/chemistry/generalchemistry/elements/periodic/formulated/mendelev.gif
Mendeleev’s Periodic Table
Property
Ekasilicon
Germanium
Atomic mass
(amu)
72
72.59
Density (g/cc)
5.5
5.35
Melting Point (C)
High
947
Color
Gray
Gray
Current Periodic Table
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Arranged by increasing
atomic # and by physical and
chemical properties
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1913, Henry Moseley
improved Mendeleev’s
periodic table by arranging
elements by atomic #
https://reich-chemistry.wikispaces.com/file/view/moseley.jpg
Groups or Families
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Vertical Columns
18 groups
Members of each group have similar properties
Some groups are given family names
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Group 1 = Alkali metals
Group 2 = Alkaline earth metals
Groups 3-12 = Transition metals
Group 17 = Halogens
Group 18 = Noble gases
Periods
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Horizontal Rows
Represent the number of energy levels
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Each energy level can hold a set # of
electrons
1st energy level = 2 electrons
2nd = 8 electrons
Increase # protons and # electrons as you
go left to right
Full valence shell
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Elements become stable by obtaining a
full energy shell of electrons
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H & He are stable with just 2 eAll other elements are stable with 8 e- in outer
energy level
Valence electrons are used in bonding
Electron dot diagrams
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Diagram that shows how many valence
electrons in outer energy levels
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Same group = same # bonding electrons
http://www.roymech.co.uk/images14/lewis_elements.gif
Regions of Periodic Table
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Metals = Blue squares
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Solids @ room temperature
Shiny
Good conductors
Regions of Periodic Table
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Non-metals = yellow squares on right side
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Most are gases
Brittle
Poor conductors
Semimetals = green staircase
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Properties of metals and non-metals
In-Class Assignment/Homework
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19.3 Reinforcement WKT
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Tomorrow – Directed Reading &
Enrichment WKT