1.3 - Bonding

• What do metal atoms do to form positive ions?

  They lose electrons
• What do non-metal atoms do to form negative ions?

  They gain electrons
• How does magnesium change when it forms Mg²⁺?

  It loses two electrons
• How does oxygen change when it forms O^2-?

  It gains two electrons
• What factors increase the strength of ionic bonding?

  Smaller ions and higher charges
• Why does MgO have a higher melting point than NaCl?

  MgO has smaller, higher charged ions
• What is the structure of ionic crystals?

  Giant lattices of ions
• Which ions have the same electronic structure as Ne?

  N^3-, O^2-, F^-, Na⁺, Mg²⁺, Al³⁺
• Why do ionic radii decrease from N to F?

  Increased protons increase nuclear attraction
• What happens to ionic radii as you go down a group?

  They increase due to more electron shells
• Why are positive ions smaller than their atoms?

  They have fewer electron shells
• Why are negative ions larger than their corresponding atoms?

  They have more electrons than protons
• What is the definition of ionic bonding?

  Electrostatic attraction between oppositely charged ions
• What is a covalent bond?

  A shared pair of electrons
• What is a dative covalent bond?

  Shared pair from one bonding atom
• What is another name for dative covalent bonding?

  Co-ordinate bonding
• What is metallic bonding?

  Attraction between positive ions and delocalised electrons
• What factors affect the strength of metallic bonding?

  Protons, delocalised electrons, ion size
• Why does Mg have a higher melting point than Na?

  Mg has more outer shell electrons
• What is the general description of ionic compounds?

  Crystalline solids
• What are the properties of ionic compounds?

  • High melting and boiling points
  • Generally good solubility in water
  • Poor conductivity when solid
  • Good conductivity when molten
• What are the properties of molecular (simple) compounds?

  • Low melting and boiling points
  • Generally poor solubility in water
  • Poor conductivity when solid
  • Poor conductivity when molten
• What are the properties of macromolecular compounds?

  • High melting and boiling points
  • Insoluble in water
  • Poor conductivity when solid
• What are the properties of metallic compounds?

  • High melting and boiling points
  • Good conductivity when solid and molten
  • Malleable and shiny
• What is the bond angle in a linear molecule?

  180 degrees

  
• What is the bond angle in a tetrahedral molecule?

  109.5 degrees
• How do lone pairs affect bond angles?

  Lone pairs reduce bond angles
• What is electronegativity?

  Atom's tendency to attract electrons in a bond
• Which atoms are the most electronegative?

  F, O, N, and Cl
• How does electronegativity change across a period?

  It increases due to more protons
• What are the shapes of common molecules and their bond angles?

  • Linear: 180 degrees
  • Trigonal planar: 120 degrees
  • Tetrahedral: 109.5 degrees
  • Trigonal pyramidal: 107 degrees
  • Bent: 104.5 degrees
  • Trigonal bipyramidal: 120 and 90 degrees
  • Octahedral: 90 degrees
• How does electronegativity change down a group?

  It decreases due to increased distance
• How to explain the shape of a molecule?

  1. State bonding and lone pairs
  2. Explain electron pair repulsion
  3. State actual shape and bond angle
• What are the factors affecting electronegativity?

  • Number of protons
  • Atomic radius
  • Shielding of inner shell electrons
• How many electrons are in the described molecule?

  10 electrons
• What type of molecular shape is formed with 4 bond pairs and 1 lone pair?

  Variation of trigonal bipyramidal
• What is the bond angle in a square planar molecule?

  90°
• How does a lone pair affect bond angles?

  Reduces bond angles slightly
• What is the bond angle in a linear molecule?

  180°

  
• What is the bond angle in a molecule with lone pairs?

  Approximately 89°