The Representative Elements:

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Chapter 18

• The Representative Elements
• Groups IA through IVA

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Ionization energy increases Electronegativity
increases Electron affinity increases Metallic
nature decreases Atomic size decreases
Higher oxidation states of T.M. become more
stable Nonmetal trends all the same Except
chemical activity decreases Higher oxidation
states less stable
Ionization energy decreases Electronegativity
decreases Electron affinity decreases
Metallic nature increases Atomic size
increases Chemical activity increases
Trends of the Periodic Table
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ELECTRONIC CONFIGURATIONvs.Periodic atomic
properties

• Factors
• Effective Nuclear Chare, Zeffective
• Pairing Energy
• Shielding Effect
• Properties
• Atomic size (radius)
• Ionic size (radius)
• Ionization energy (ionization potential)
• Electron affinity (opposite of ionization)
• Melting point / boiling point
• Density and conductivity

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SHIELFING EFFECTvs.ORBITAL FILLING ORDER

• Electrons always fill the lowest energy orbitals
  first.
• Ens lt Enp lt End lt Enf
• n is the period number,
• s, p, d and f are the orbitals
• Underlying electrons shield outside electrons to
• varying degrees. This contributes to a few
• exceptions to the filling order.
• Least shielding ?? most shielding
• Of outer e- of outer e-
• ns gt np gt nd gt nf
• All exceptions occur with a tendency to get an
  orbital full or half full. This lowers its
  overall energy.

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Atomic Radii for selected atoms
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Atomic Radii of the representative elements are
expressed in picometers
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Sizes of monatomic ions in the periodic table
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Structure of Silicate Minerals

• Three- Feldspars, Structure is like
• dimensional KAlSi3O8 SiO2 with some Si
• framework Zeolites, substituted by
• Na2(Al2Si3O10).2H2O other elements.