Theory - Unit 3 Bonding Flashcards
Bond Pairs
Pairs of electrons which form a bond.
Lone Pairs
Electron pairs which are not involved in bonding. They do however, affect the shape because electron pairs repel other electron pairs.
Rules for Writing Lewis Dot Structures
- Total the Valence Electrons and Update during each step.
- Form a single bond between the central atom and each surrounding atom (each bond uses two electrons).
- Place electrons around the outer atoms until you run out or they each have eight electrons around them. (Hydrogen and Helium can only have two electrons around them).
- Place any remaining electrons around the central atom.
- Does each atom other than hydrogen have eight electrons around it?
- Rearrange (share) electrons so that all atoms other than hydrogen have eight electrons around them.
Octet Rule
All atoms other than hydrogen and helium bond to fill their valence shell with eight electrons.
Duet Rule
Hydrogen bonds to fill it’s valence shell with two electrons. Helium already has two electrons and thus does not need to form bonds to increase stability.
Violations of the Octet Rule
Be - 4
B - 6
P - 8 or 10
S - 8, 10, or 12
Xe - 8, 10, or 12
VSPER
Valence Shell Electron Pair Repulsion
Most important aspect of determining the shape or geometry of a molecule. The molecule will adopt the shape which minimizes te electron pair repulsion.
What is the Lewis dot structure of Br₂?
What is the Lewis dot structure of XeF₄?
What would the Lewis dot structure of OC be?
Hydrogen
Group 1 Nonmetal
Ionic Bond
Metals GIVE electrons, Nonmetals TAKE electrons
Naming Ionic Bonds
State the name of the metal followed by the nonmetal with the ending changed to “ide”. If the metal is a transition metal, add a (Roman numeral). AlCl₃ = Aluminum Chloride CuCl₃ = Copper (III) Chloride
Writing Formulas for Ionic Bonds
Absolute Value Criss Cross Oxidation #’s
Polyatomic Ion
A group of atoms that acts like an ion (has a charge)
Properties of Ionic Compounds
Crystalline Structure High Melting Point Rigid Strong Bond Conduct Electricity (when dissolved or melted) Good Insulators