Bonding

• Ionic bonding


  Charged ions held together by strong electrostatic attractions
• Formation of ionic bond

  1. Atom gives up electron to another atom

  2. Oppositely charged ions are attracted to each other
• Molecular ions


  Hydroxide (OH-), Nitrate (NO3-), Ammonium (NH4+), Sulfate (SO4 2-), Carbonate (CO3 2-)
• Determining formula of ionic compound

  1. Write the two ions

  2. Swap the charges over

  3. Drop the charges to get the subscripts

  4. Simplify the formula
• Giant ionic structures


  • Cubic arrangement of ions
  • High melting points due to strong electrostatic forces
• Covalent bonding


  Sharing of electrons between atoms to achieve stable electron configurations
• Types of covalent bonds

  • Single
  • Double
  • Triple
• Dative covalent (coordinate) bond


  One atom donates a pair of electrons to another atom
• Giant covalent structures


  • Graphite: Layers of hexagons with delocalized electrons, can conduct electricity
  • Diamond: Tetrahedral structure with strong covalent bonds, does not conduct electricity
• Molecular shape


  Determined by number of bond pairs and lone pairs of electrons around central atom
• Molecular shapes with no lone pairs

  • Linear (2 bond pairs)
  • Trigonal planar (3 bond pairs)
  • Tetrahedral (4 bond pairs)
  • Trigonal bipyramidal (5 bond pairs)
  • Octahedral (6 bond pairs)
• Molecular shapes with lone pairs

  • Pyramidal (3 bond pairs, 1 lone pair)
  • Bent/Angular (2 bond pairs, 2 lone pairs)
  • Trigonal planar (3 bond pairs, 2 lone pairs)
• Octahedral


  Molecular shape with 6 bond pairs or lone pairs arranged in an octahedral geometry
• Pyramidal


  • Molecular shape with 3 bond pairs and 1 lone pair
  • Example: ammonia
• Bent/Nonlinear


  • Molecular shape with 2 bond pairs and 2 lone pairs
  • Bond angle shrinks from 107 to 104.5 degrees
• Trigonal planar


  • Molecular shape with 3 bond pairs and 2 lone pairs
  • Bond angle remains at 120 degrees
• Tetrahedral


  • Molecular shape with 4 bond pairs and 2 lone pairs
  • Bond angle remains at 90 degrees
• Electronegativity


  The ability for an atom to attract electrons towards itself in a covalent bond
• The further up and right you go in the periodic table, the more electronegative the element is (excluding noble gases)
• Polar bond


  Covalent bond where there is a difference in electronegativity between the atoms, resulting in an uneven distribution of electrons
• Polar bonds


  • H-Cl
  • H2O
• Non-polar bonds


  • Cl2
  • Hydrocarbons
• Intermolecular forces

  Weak forces between molecules, not within covalent bonds
• Van der Waals forces

  • Weakest intermolecular force, induced dipole-dipole interactions
  • Larger molecules have stronger van der Waals forces
• Dipole-dipole forces


  • Stronger than van der Waals, occur between permanent dipoles
• Hydrogen bonding


  • Strongest intermolecular force, occurs between H and highly electronegative N, O, or F
• Ice expands when cooled due to hydrogen bonding pushing molecules apart
• Metallic bonding


  Giant lattice of positive metal ions with delocalized electrons in between
• Metallic properties


  • High melting points
  • Good thermal and electrical conductors
  • Insoluble in water
• Particle model


  Describes the arrangement and motion of particles in solids, liquids and gases
• Bond types


  • Giant covalent
  • Simple molecular
  • Giant ionic
  • Metallic
• Polar molecules dissolve in polar solvents like water, non-polar molecules dissolve in non-polar solvents
• Cubic Arrangement


  In a cubic arrangement, ions are arranged in a three-dimensional grid where each ion is surrounded by eight counter-ions in the shape of a cube. This arrangement is highly symmetrical and efficient, which leads to strong electrostatic forces between oppositely charged ions.
• Non-cubic Arrangement


  In a non-cubic arrangement, ions are arranged in a three-dimensional grid that is not in the shape of a cube. This can take many forms, such as hexagonal or tetragonal. In these arrangements, the ions are not as efficiently packed as in a cubic arrangement, which can lead to weaker electrostatic forces between oppositely charged ions.
• High Melting Points


  Giant ionic structures with cubic arrangements of ions have high melting points due to the strong electrostatic forces between oppositely charged ions.
• Low Melting Points


  Giant ionic structures with non-cubic arrangements of ions have lower melting points due to the weaker electrostatic forces between oppositely charged ions.
• Symmetrical Arrangement


  Cubic arrangements of ions in giant ionic structures are highly symmetrical, which allows for a more uniform distribution of charges and a more efficient packing of ions.
• Efficient Packing


  Cubic arrangements of ions in giant ionic structures allow for efficient packing of ions, which maximizes the number of attractive electrostatic interactions between oppositely charged ions.
• Uniform Distribution of Charges

  Cubic arrangements of ions in giant ionic structures allow for a more uniform distribution of charges, which leads to stronger electrostatic forces between oppositely charged ions.
• Weak Electrostatic Forces


  Non-cubic arrangements of ions in giant ionic structures can lead to a less uniform distribution of charges and weaker electrostatic forces between oppositely charged ions.