Modern Periodic Table
Part I
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Introduction.
Periods and groups.
Metals, nonmetals and metalloids.
The Modern Periodic Table
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The Periodic Table is a listing of all the
known elements.
The elements are organized by:
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Atomic number
Chemical Properties
Groups and Periods
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Group( or Family): a vertical column.
Elements in groups have similar
chemical properties.
Period: a horizontal row.
Groups and Periods are
numbered.
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There are 7 periods.
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There are 18 numbered columns.
IUPAC
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International Union of Pure and Applied
Chemistry
1985 new system for labeling groups.
Metals, Nonmetals and Metalloids
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Elements can be classified into:
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Metals
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Nonmetals
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Metalloids (semimetals)
Metals
Nonmetals
Metalloids
Actinides and Lanthanides
Physical Properties of Metals
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Good conductors of electricity and heat.
Malleable (can be hammered into sheets).
Ductile (can be drawn into wires).
Lustrous.
Chemical Properties of Metals
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Easily lose electrons.
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Form positive (+) ions.
Nonmetal Physical Properties
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They do not have the properties of
metals.
Nonmetal Chemical Properties
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Gain electrons.
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Form negative ions.
Part II
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Valence Electrons
Group 1
Group 2
-Niels Bohr’s Model –
Distinct Energy Levels
Periods
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The periods (rows) of the periodic table
indicate the highest energy level
occupied by one or more electrons.
Valence Electrons
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The electrons the occupy the highest
energy level of an atom.
Valence electrons play a key role in the
chemical properties of an element.
“A” Groups (Old System)
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The “A” groups are numbered 18.
The number of the “A” groups
correspond to the number of valence
electrons.
Group 1- Alkali Metals
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1 valence electron (ns1)
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Form a 1+ ion.
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Note: Hydrogen, a nonmetal, is located
in the first column because it has one
valence electron.
Group 1- Alkali Metals
Lithium
Sodium
Potassium
Rubidium
Cesium
Francium
Sodium’s Reaction with H2O
Produces Hydrogen
Reactivity of Alkali Metals
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Increases from top to bottom of the
group.
Which is more reactive Cesium or
Sodium?
Note:
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Sodium and Potassium are stored in oil
to keep them from reacting with oxygen
and water in the air.
Cesium is stored in glass tubes of argon
gas( an inert gas).
Group 2- Alkali Earth Metals
Beryllium
Magnesium
Calcium
Strontium
Barium
Radium
Group 2- Alkali Earth Metals
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Have 2 valence electrons.
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Form 2+ ions.
Group 2- Alkali Earth Metals
Reactions with Water
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Be does not react with water.
Mg reacts with hot water.
Ca, Sr, Ba react easily with cold water.
Which way along the group does
reactivity increase?
The Periodic Table