Agenda

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Agenda

• Reading for the night Ebola
• Vocabulary Check
• Lesson Mendeleev History
• One Element at a time project

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Organizing the Elements
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Looking for Patterns in the Elements

• Record the activities of a typical day
• Monday
• Tuesday
• Wednesday
• Thursday
• Friday

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• Notice any patterns
• Matter is made up of about 100 different elements
  that have a variety of properties
• These elements like your daily activities follow
  a pattern.

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Mendeleev, the Detective

• 1800s scientists suspect the elements
  could
• be organized in useful way.
• 1869, Russian scientist,
• Dmitri Mendeleev,
• recognized a hidden
• pattern in the elements.

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• One of his first observations was that some
  elements have similar chemical and physical
  properties.
• Examples
• Fluorine and Chlorine, both gases that irritate
  your lungs if you breathe them in.
• Silver and Copper are both shiny metals that
  gradually tarnish if exposed to air.

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• Mendeleev believed that these similarities were
  important clues to the pattern he was looking
  for.
• He wrote the facts about the elements on paper
  cards.
• He wrote all the properties he knew about an
  element, including its melting point, density and
  color.

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• Mendeleev also recorded two other important
  properties
• atomic mass
• bonding power.
• The atomic mass is the average mass of one atom
  of an element.

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One Element at a Time Project
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• Mendeleev found the atomic mass of elements
  from the elements comparison to hydrogen, the
  lightest of elements.
• Bonding power refers to the number of chemical
  bonds an element can form.
• This was determined by studying how each
  element formed compounds with oxygen.

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First Periodic Table

• Mendeleev took his note cards and began to
  arrange them in different patterns.
• He noticed that patterns appeared when the
  elements were arranged in order of increasing
  atomic mass. He noticed that the elements bonding
  power changed in an orderly way too.

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• As Mendeleev discovered, arranging the elements
  by increasing atomic mass does not produce a
  perfect table.
• He moved the cards to positions where they fit
  be.
• By doing so this left 3 blank spaces. He boldly
  stated that these spaces would be filled in
  eventually because they had not yet been
  discovered.

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• 1869 Mendeleev published the first periodic
  table of elements.
• Periodic means regular repeating pattern.
• In the modern Periodic Table, the properties of
  the elements repeat in each row or period of
  the table.
• Within the next 16 years scientists found
  Mendeleevs missing elements.

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Homework

• 1. Begin your project pick an element
• 2. Research that element fill in the graphic
  organizer
• 3. Finish nightly reading and questions