IOC

• Covalent bond


  Sharing of electrons between two atoms
• Molecule


  Discrete group of atoms held together by covalent bonds
• Non-bonded electron pairs


  Lone pairs
• Atoms share electrons to


  Attain the electronic configuration of the noble gas closest to them in the periodic table

  
• H shares

  2 electrons
• Other main group elements share electrons until

  They reach an octet of electrons in their outer shell
• Lewis structure


  Electron-dot structure for molecules showing the location of all valence electrons

  
• Covalent bonds


  • Formed when two nonmetals combine, or when a metalloid bonds to a nonmetal
  • Atoms with one, two, or three valence electrons form one, two, or three bonds, respectively
  • Atoms with four or more valence electrons form enough bonds to give an octet
• Molecular formula


  Shows the number and identity of all of the atoms in a compound, but not which atoms are bonded to each other

  
• Lewis structure


  Shows the connectivity between atoms, as well as the location of all bonding and nonbonding valence electrons

  
• General rules for drawing Lewis structure

  1. Draw only valence electrons

  2. Give every main group element (except H) an octet of electrons

  3. Give each hydrogen 2 electrons

  
• Multiple bonds


  • One lone pair of electrons can be converted into one bonding pair of electrons for each 2 electrons needed to complete an octet on a Lewis structure
  • A double bond contains four electrons in two 2-electron bonds
  • A triple bond contains six electrons in three 2-electron bonds

  
• Exceptions to the octet rule

  • H is a notable exception, because it needs only 2 electrons in bonding
  • Elements in group 3A do not have enough valence electrons to form an octet in a neutral molecule
  • Elements in the third row have empty d orbitals available to accept electrons, so elements such as P and S may have more than 8 electrons around them

  
• Resonance structures


  • Two Lewis structures having the same arrangement of atoms but a different arrangement of electrons
  • The true structure is a hybrid of the two resonance structures
  • Resonance stabilizes a molecule by spreading out lone pairs and electron pairs in multiple bonds over a larger region of space
  • A molecule or ion that has two or more resonance structures is resonance-stabilized

  
• Drawing resonance structures


  Add one electron for each negative charge and subtract one electron for each positive charge

  
• Electronegativity


  A measure of an atom's attraction for electrons in a bond, the ability of an atom to attract electron pair to itself, forming covalent bond, how much a particular atom "wants" electrons

  
• Nonpolar bond


  Electrons in the bond are being shared equally between the two atoms
• Polar covalent bond or dipole


  Bonding between atoms with different electronegativities, electrons are unequally shared between the atoms

  
• Polarity of molecules


  • Depends on the polarity of the individual bonds and the overall shape of the molecule
  • Nonpolar molecules generally have no polar bonds and individual bond dipoles that cancel
  • Polar molecules generally have only one polar bond and individual bond dipoles that do not cancel