Periodic Table History

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Periodic Table History

• Dmitri Mendeleev (1869)
• Creates periodic table with elements listed in
  increasing mass.
• Finds that properties repeat in the table.

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http//www.dlt.ncssm.edu/TIGER/diagrams/periodic/
MendeleevPrediction.gif
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Periodic Table History

• Henry Moseley (1913)
• Current periodic table which lists in order of
  atomic number, from smallest to largest.

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The Periodic Table
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The Periodic Table
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The Periodic Table

• Periods Each horizontal row of the periodic
  table.

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The Periodic Table

• Groups Each vertical column of the periodic
  table, also known as families.
• Elements in a group have similar properties.

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The Periodic Table Electrons

• The shape of the periodic table is due to where
  the electrons are located in an atom.

Nothing here???
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The Periodic Table Electrons

• Blocks of the periodic table represent the last
  type of cloud that electrons occupy.

S Cloud
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S Cloud
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P Clouds
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The Periodic Table Electrons

• Electron Configurations show where electrons are
  located in an atom.
• Example H is 1s1

of Electrons
Period
Cloud Type
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The Periodic Table Electrons
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Example Oxygen
1s2
2s2
2p4
(e- 8)
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The Periodic Table Electrons
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Example Magnesium
(e- 12)
1s2
2s2
2p6
3s2
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The Periodic Table Electrons

• Valence Electrons are the outside electrons in
  an atom
• Highest period number Highest energy level

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The Periodic Table Electrons

• Or you could look at the group number
• Silicon has 4 valence electrons