Chemistry: Chemical Bonds

Trying to catch up in my snails progress through various science and math resources.  Here's my review notes for a chemistry chapter on chemical bonds.

• The octet rule is the fact that (except for H and He), the outermost electron shell of Groups 1A-7A want to have eight electrons.
• For those in the outer groups, there will be a tendency to go into ions, so those on the right tend to become cations (positive ions) by losing electrons to end up with the 8 outer electrons of a lower shell.  Those on the left tend to gain electrons and become negatively charged anions to fill up the outermost shell they start with.
• Electronegativity is how strongly an atom holds on to its electrons.  It increases from left to right on the periodic table and from bottom to top in a column (as does ionization energy).
• An ionic bond forms with a difference in electronegativity of 1.9 or greater between two atoms.  A covalent bond forms if less than 1.9.  A non-polar covalent bond forms if the difference in electronegativity is below 0.5.
• In an ionic bond, electrons transfer from one atom to another (e.g., from Na to Cl).  In a covalent bond, two atoms share electrons (mostly elements toward the middle of the periodic table).  In a polar covalent bond (electronegativity between 0.5 and 1.9), electrons are shared but gravitate more toward one atom than another (the one more to the right and top in the table).  Such a polarized compound is called a dipole.
• An ion can be one type of element (monatomic, add -ide) to it (choride).  An ion can also be polyatomic.  To name a binary ionic compound, name the first (cation) element, then the second (anion).  "Ous" and "ic" (think ars-en-ic with a British accent) are the lower and higher charged ions of an element that can form more than one ion (e.g., Fe).
• A binary molecular compound will use di- tri- and so forth.
• VSEPR or Valence Shell Electron Pair Repulsion model predicts the structure of a compound.  An atom with 4 regions of electron density would be tetrahedral with default angles of 109.5 degrees.  Three regions would be pyramidal with a default of 120 degrees.  Two regions would be linear (180 degrees).