Ch' 6 The Periodic Table

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Ch. 6 The Periodic Table
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Mendeleevs Periodic Table

• Elements in the periodic table are arranged by
  repeating properties
• Arranged in order by increasing atomic mass
• Left spaces where he predicted future elements
  would fit

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Mendeleevs Periodic Table
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Periodic Law

• In the modern periodic table, elements are
  arranged in order by increasing Atomic Number
• 7 horizontal rows called periods
• Each period corresponds to a principle energy
  level
• Elements within a column (group) have similar
  properties

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Periodic Law

• States when elements are arranged by increasing
  atomic number, there is a periodic repetition of
  their physical and chemical properties

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Metals, Nonmetals, Metalloids
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Metals

• 80 of the periodic table is metals
• Good conductors of heat and electricity
• Malleable- can be shaped
• Ductile- can be drawn into wires
• Lustrous
• Solids at room temperature (except Hg)

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Nonmetals

• Poor conductors of heat and electricity
• Not malleable
• Not ductile
• dull

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Metalloids

• Generally has some properties of a metal, some of
  a nonmetal

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Alkali Metals
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Alkaline Earth Metals
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Halogens
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Noble Gasses
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Trends in Atomic Size

• Atomic radius is ½ the distance between the
  nuclei of 2 like atoms
• As you move DOWN a group, atomic size increases
• As you move LEFT to RIGHT across a period size
  decreases

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Why?
As you move across the period you gain electrons
but you also gain protons. More protons hold
their electrons tighter
As you move down the group you gain more
electrons which are in electron orbitals further
away from the nucleus. The nucleus has less
influence the further out you move.
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Trends in Ionization Energy

• Ionization Energy is the energy required to
  remove 1 electron from a gaseous atom
• As you move DOWN a group ionization energy
  DECREASES
• As you move LEFT to RIGHT across a period
  ionization energy INCREASES

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Why?
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Trends in Electronegativity

• Electronegativity is the tendency of an atom to
  attract electrons in a compound
• As you move DOWN a group Electronegativity
  DECREASES
• As you move LEFT TO RIGHT across a period
  Electronegativity INCREASES

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Summary of Periodic Trends