The Periodic Table

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The Periodic Table
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During the nineteenth century, chemists began to
categorize the elements according to similarities
in their physical and chemical properties. The
end result of these studies was our modern
periodic table.
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Dmitri Mendeleev
In 1869 he published a table of the elements
organized by increasing atomic mass.
1834 - 1907
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Lothar Meyer
At the same time, he published his own table of
the elements organized by increasing atomic mass.
1830 - 1895
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Henry Moseley
In 1913, through his work with X-rays, he
determined the actual nuclear charge (atomic
number) of the elements. He rearranged the
elements in order of increasing atomic number.
There is in the atom a fundamental quantity
which increases by regular steps as we pass from
each element to the next. This quantity can only
be the charge on the central positive nucleus.
1887 - 1915
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Periodic Table Geography
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Periodic Table

• Columns called Families/Groups
• Family indicates valence (outer shell)
  electrons
• Elements in same family have similar properties
• Rows called Periods
• Row indicates energy levels in atom

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The horizontal rows of the periodic table are
called PERIODS.
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The elements in any group of the periodic table
have similar physical and chemical properties!
The vertical columns of the periodic table are
called GROUPS, or FAMILIES.
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Metals/Nonmetals/Semiconductors

• Metals excellent conductors of heat
  electricity have luster, are ductile/malleable
• Nonmetals poor conductors of heat electricity
  are dull brittle
• Semiconductors(Metalloids) elements that under
  certain conditions conduct heat electricity

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Families of Elements

• Family 1 Alkali Metals
• Family 2 Alkaline Earth Metals
• Families 3 to 12 Transition Metals
• Family 13 Boron Family
• Family 14 Carbon Family
• Family 15 Nitrogen Family
• Family 16 Oxygen Family
• Family 17 Halogens
• Family 18 Noble Gases
• Three general groups metals, nonmetals,
  semiconductors(metalloids)

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Periodic Table
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Periodic Law
When elements are arranged in order of increasing
atomic number, there is a periodic pattern in
their physical and chemical properties.
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Alkali Metals
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Alkaline Earth Metals
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Transition Metals
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Metals

• Alkali metals (Family 1)
• Very reactive
• Has 1 valence electron
• When ionized has charge of 1
• Alkaline Earth metals (Family 2)
• Reactive
• Has 2 valence electrons
• When ionized has charge of 2
• Transition metals (Families 3 to 12)
• Somewhat reactive
• Valence electron number varies
• Ionized charge varies

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InnerTransition Metals
These elements are also called the rare-earth
elements.
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Halogens
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Noble Gases
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Nonmetals

• Include H, some elements from families 13 to 16,
  all elements from families 17 18. Zig-zag line
  divides metals from nonmetals.
• Inert gases are unreactive contain 8 valence
  electrons
• Halogens are very reactive contain 7 valence
  electrons gain electrons becoming negatively
  charged
• Elements in other families gain electrons to
  become negatively charged
• These elements plentiful on Earth

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Semiconductors(aka Metalloids)

• Located along the zig-zag line
• Includes
• Boron (B) Silicon (Si), Germanium (Ge), Arsenic
  (As), Antimony (Sb), Tellurium (Te), Polonium
  (Po)
• Notice that Al is not considered a metalloid, it
  is considered a metal
• Conduct heat electricity under certain
  conditions
• B is hard added to steel to increase hardness
  Sb is bluish-white and shin, Te is silvery-white
  electrical conductivity increases with light
  exposure, Si important in solar cells
  integrated circuits

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Periodic Table Trends
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1. Atomic Size - Group trends
H

• As we increase the atomic number (or go down a
  group). . .
• each atom has another energy level,
• so the atoms get bigger.

Li
Na
K
Rb
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1. Atomic Size - Period Trends

• Going from left to right across a period, the
  size gets smaller.
• Electrons are in the same energy level.
• But, there is more nuclear charge.
• Outermost electrons are pulled closer.

Na
Mg
Al
Si
P
S
Cl
Ar
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2. Trends in Ionization Energy

• Ionization energy is the amount of energy
  required to completely remove an electron (from a
  gaseous atom).
• Removing one electron makes a 1 ion.
• The energy required to remove only the first
  electron is called the first ionization energy.

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Ionization Energy

• The second ionization energy is the energy
  required to remove the second electron.
• Always greater than first IE.
• The third IE is the energy required to remove a
  third electron.
• Greater than 1st or 2nd IE.

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3. Trends in Electronegativity

• Electronegativity is the tendency for an atom to
  attract electrons to itself when it is chemically
  combined with another element.
• They share the electron, but how equally do they
  share it?
• An element with a big electronegativity means it
  pulls the electron towards itself strongly!

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Electronegativity Group Trend

• The further down a group, the farther the
  electron is away from the nucleus, plus the more
  electrons an atom has.
• Thus, more willing to share.
• Low electronegativity.

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Electronegativity Period Trend

• Metals are at the left of the table.
• They let their electrons go easily
• Thus, low electronegativity
• At the right end are the nonmetals.
• They want more electrons.
• Try to take them away from others
• High electronegativity.

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The periodic table is the most important tool in
the chemists toolbox!