Chemistry Test Review 11/11

Types of Bonds
- Ionic: Electron transfer; Non-metal + Metal; smallest particle=Formula unit.
- Covalent: Electron sharing; Non-metals + non-metals/metaloids. smallest unit=molecule
  - polar = unpaired sharing
  - nonpolar = equal sharing
- Metallic: Delocalized electrons; Metals + Metal.
Properties
- Ionic: Very soluble, High melting point, Strong conductor in solution. (BIG)
- Polar Covalent: Soluble, Moderate melting point, Poor conductor. (MEH)
- Nonpolar Covalent: Insoluble, Low melting point, Insulator. (SMALL)
- Metallic: Insoluble, High melting point, Very good conductor.
Substance Classification
- A: Polar; B: Nonpolar; C: Ionic; D: Metallic.

Bond Types Based on Electronegativity
- Nonpolar: 0.0 - 0.50
- Polar: 0.5 - 1.70
- Ionic: 1.70 and greater.
Compounds Classification are based on Electronegativity values.

1 - mono

2 - di

3 - tri

4 - tetra

5 - penta

6 - hexa

7 - hepta

8 - octa

9 - nona

10 - deca

Compound Formulas: Covalent and Ionic classifications with specific examples.

tricarbon octahydride - C3H8

sodium nitrate - NaNO3

lead (II) chlorate - Pb(ClO3)2

silicon dioxide - SiO2

Li2CO3 - lithium chlorate

Cl2O7 - dichlorine heptoxide

N2O4 dinitrogen tetroxide

Cr(NO3)2 - chromium nitrate

***do not reduce number for covalent molecules, ONLY ionic***

RULES

total valence elctrons (even number)
place central atom (least electronegative)
subtract the number of electrons used in bonds
assign remaining to lone pairs until octet on terminal atoms
leftover electrons go to the central atom
if the central atom does not have an octet after all other steps, create double and triple bonds (boron and beryllium don’t always need octet)
***Identify Elements in Lewis Structures based on the true octet rule.

FORMAL CHARGE

formal charge = [# of valence electrons on atom] - [non-bonded electrons + # of bonds]