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
• Why do ionic compounds have higher melting points when ions are smaller or have higher charges?

  Stronger ionic bonds form with smaller ions
• What happens to oxygen when it forms O^2-?

  It gains two electrons
• Which has a higher melting point, MgO or NaCl?

  MgO
• What is the structure of ionic crystals?

  Giant lattices of ions
• What is the ionic radius trend within a group?

  Increases going down the group
• Why are positive ions smaller than their atoms?

  They have one less shell of electrons
• 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?

  Coordinate 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?

  Stronger metallic bonding in Mg
• What are the properties of ionic compounds?

  • High melting and boiling points
  • Generally soluble in water
  • Conduct electricity when molten
  • Crystalline solids
• What are the properties of molecular (simple) substances?

  • Low melting and boiling points
  • Generally poor solubility in water
  • Poor conductivity
  • Mostly gases and liquids
• What are the properties of macromolecular substances?

  • High melting and boiling points
  • Insoluble in water
  • Poor conductivity (except graphite)
  • Solid structures
• What are the properties of metallic substances?

  • High melting and boiling points
  • Good conductivity
  • Malleable and ductile
  • Shiny appearance
• 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?

  They reduce bond angles by about 2.5°
• What is the method to explain molecular shape?

  1. State bonding and lone pairs
  2. Explain electron pair repulsion
  3. Describe equal repulsion with no lone pairs
  4. Describe greater repulsion with lone pairs
  5. State actual shape and bond angle
• What is electronegativity?

  Ability of an atom to attract electrons
• Which atoms are the most electronegative?

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

  It increases across a period
• How does electronegativity change down a group?

  It decreases down a group
• What are the factors affecting electronegativity?

  • Number of protons
  • Atomic radius
  • Shielding effect of inner 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°
• What is the bond angle in a molecule with 5 bond pairs?

  Approximately 119° and 89°

  
• What is electronegativity?

  Attraction of an atom for electrons in a bond
• How does electronegativity change across a period?

  Increases as atomic radius decreases
• How does electronegativity change down a group?

  Decreases due to increased distance