Periodic properties and chemical bonding

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Periodic properties andchemical bonding

• Chapter 7-8

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Periodic Properties

• Periodic Chart is organized relative to periodic
  properties (by families)
• Chemical Bonding occurs in order to follow the
  Octet Rule
• Octet Rule states that a point of stability
  within chemicals occurs with a s2p6 configuration

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Atomic Radius

• Distance between nucleus and outmost electron in
  a bonded atom

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Ionization Energy

• Energy needed to remove the most loosely held
  electron from the atom

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Exceptions to periodic trends

• Other points of stability occur within chemistry
• Full subshells (s2 p6 d10 f14)
• ½ full subshells (s1 p3 d5 f7)

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Ionic radius

• Distance from the nucleus to the outermost
  electron in an atom
• Cations smaller than the original atom
• Anions larger than the original atom

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Electron Affinity

• Energy released when an additional electron is
  acquired by the atom
• (Desire for additional electron)

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Metallic Characteristic

• Metal Properties
• Nonmetal Properties
• Metalloids

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Electronic Configuration

• Also follows periodic properties because
  electrons in the outer energy level are the
  makers of properties

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Electronegativity

• Ability of an atom to attract electrons to
  itself, when involved in bonding
• Differences in electronegativity (END) determines
  bond character
• Large difference (END gt 1.67) is strongly IONIC
• Small difference(ENDlt1.67) is strongly COVALENT

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HOMEWORK

• Chapter 7
• 16,18,19,24,32
• Chapter 8
• 1,2,4,8,10,23,24,38

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IONIC BONDING

• Complete transfer of electrons due to large
  differences in electronegativity (ENDgt1.67)
• Metal Nonmetal
• Charged particles held together by electrostatic
  force of attraction called Lattice Energy
• ionic bonding example

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IONIC BONDING

• Bond Character (mostly due to charged ions)
• Intraparticle (within)
• Strong bond
• High solubility (strong electrolyte)
• High conductivity in aqueous solution
• Interparticle (between)
• Usually solids
• High melting point
• Crystalline (ionic compound)
• Hard

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COVALENT BONDINGor MOLECULAR BONDING

• Sharing of electrons due to small differences in
  electronegativity (END lt 1.67)
• Nonmetal Nonmetal
• Held together by sharing of electron to satisfy
  octet rule
• covalent bonding example
• Pure Covalent Bond (equal sharing of e-)
• Polar Covalent Bond (unequal sharing or e-)
• polar molecule

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POLAR MOLECULE

• Polarity of a covalently bonded particle effects
  a variety of properties and is an important
  concept in chemistry
• Polarity occurs when there is an
• ASYMETRICAL CHARGE DISTRIBUTION and a dipole or
  polar molecule is created

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COVALENT BONDINGor MOLECULAR BONDING

• Bond Character mostly due to sharing of electrons
• Intramolecular (within)
• Weak bond
• Low solubility (remains intact as molecule)
• Low conductivity in aqueous solution
• Intramolecular (between)
• Usually gas, liquid or low melting point solid
• Low boiling point
• Amorphous (noncrystalline)

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POLAR MOLECULESor DIPOLES

• Ex NH3 , CH4 , O2

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METALLIC BONDING

• Delocalized electrons travel among the nuclei
• SEA OF ELECTRONS
• Properties
• Very strong bonds
• Highly conductive in solid form
• High melting point