PERIODIC TABLE

• Chemical bond


  A region that forms when electrons from different atoms interact with each other; valence electrons are electrons that can participate in the formation of a chemical bond
• Types of compounds and chemical bonds

  • Ionic
  • Covalent
  • Metallic
• Ionic bonds


  • Formed when one atom accepts or donates one or more of its valence electrons to another atom
  • Form crystals
  • Have high melting and boiling points
  • Are hard and brittle
  • Are poor conductors when solid, good conductors when dissolved in water
• Covalent bonds


  • Formed when atoms share valence electrons
  • May result in a polar covalent bond if atoms do not share electrons equally
  • Tend to be soft and relatively flexible
  • Most have relatively low melting and boiling points
  • Tend to be more flammable
  • Many are insoluble in water and those that do dissolve do not conduct electricity
• Metallic bonds


  • Formed when free electrons are shared by two metallic atoms
  • Have moderately high melting points
  • Are malleable and ductile
  • Are good conductors of heat and electricity
• Intermolecular forces


  Forces that hold molecules together, in contrast to intramolecular forces that hold atoms together in molecules
• Types of intermolecular forces

  • Van der Waals forces (London dispersion, dipole-dipole, induced dipole)
  • Hydrogen bonding- Formed when an electronegative atom (N, O,F) intersects with another electronegative atom bound
• Strength of intermolecular forces from weakest to strongest: London dispersion < dipole-dipole < H-bonding < electrostatic interaction
• Effects of intermolecular forces

  • Crystalline formation
  • Vapor pressure
  • Boiling and melting point
  • Surface tension
  • Capillarity
  • Adhesion/cohesion
  • Viscosity
  • Diffusion
  • Heat capacity
  • Critical point
• VSEPR theory


  Assumes that electron pairs in the valence shell of a central atom will adopt an arrangement that minimizes repulsion between these electron pairs by maximizing the distance between them
• Electron pair geometries

  • Linear
  • Trigonal planar
  • Bent or angular
  • Tetrahedral
  • Trigonal pyramid
  • Trigonal bipyramid
  • Sawhorse or seesaw
  • Octahedral
  • Square pyramid
  • Square planar
  • T-shape
• Ionic compound naming

  Cations are named first before anions, and the anion will end with -ide
• Covalent compound naming

  Numeral prefixes are used
• Polyatomic ions


  Groups of covalently bonded atoms that carry an electric charge
• In the reaction Cr + Sn2+ → Cr3+ + Sn, Cr is being oxidized and Sn2+ is being reduced
• Ideal gas


  A gas where all interactions between the molecules are only through collisions that are assumed to be completely elastic, and the gas is considered to have mass but no volume
• At standard temperature and pressure (0°C, 1 atm), 1 mole of an ideal gas occupies 22.4L