Chemical Periodicity

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Chemical Periodicity
Periodic Table and
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• Atomic Size
• Quantum mechanical model doesnt sharply define
  boundary to limit size
• Atomic radius ½ the distance between nuclei of 2
  like atoms in a diatomic molecule

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Atomic size
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Atomic Size
Atomic Size Increasing
Fatty Francium
Atomic Size Increasing
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Octet Rule atoms want 8 e- in their valence
energy level Ionization Energies amount of
energy required to remove an electron from the
valence shell of an atom Nobel Gases - dont
want to lose e- so they have very high
ionization energy Li - doesnt take much energy
to lose e-, low ionization energy F - wants to
gain an e- , therefore takes large amount of
energy to pull off an e-, high ionization energy
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• As you move down a group the ionization energy
  decreases b/c of the shielding effect

Inner e- tend to push outer e- away from the
nucleus b/c both have negative charges

• As a result of this shielding effect outer e- are
  less tightly bound to the nucleus than inner e-

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D. Ionization Energy (cont.)
Friendly Fluorine
Ionization Energy Increase
Ionization Energy Increase
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Ionic Size

• Ion positively (cation) or negatively (anion)
  charged atom, gains or loses electrons

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Electronegativity

• The electronegativity of an element is the
  tendency for the atoms to attract e- when they
  are chemically combined with another element
• Noble Gases have NO electronegativity b/c they
  dont gain e-
• Increase from left to right b/c of octet rule
• Decrease when move down a group b/c of shielding
  effect

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E. Electronegativity (cont.)
Electronegativity Increase
Electronegativity Increase
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F. Summary of Trends
Friendly Fluorine
Electronegativity Increase
F
Ionization Energy Increase
Periodic Table of the Elements
Ionic Size Increasing
Atomic Size Increasing
Electronegativity Increase
Ionization Energy Increase
Fr
Fatty Francium