Exam 1 Flashcards
How do you calculate formal charge?
FC = VE-NBE-B
Formal Charge = # valence electrons - nonbonding electrons - bonding electrons
Which compounds usually have nonbonding electrons in their stable compounds?
Oxygen, nitrogen, and the halogens (F,Cl,Br,I)
Name the halogens.
F, Cl, Br, I
Common Bonding Patterns (Uncharged) for C, N, O, H and halogens
Helpful to remember these when drawing Lewis structures
Common Bonding Patterns in Organic Compounds and Ions
What allows for a hydrocarbon to be a stable compound?
1) An octet on all atoms
2) Even number of hydrogens
General rule for the number of hydrogen atoms in stable hydrocarbons?
Even number of hydrogen atoms
Pauling Electronegativities
- know the trend and values!
Define stereoisomer
-isomers that differ only in how their atoms are oriented in space
-Atoms are bonded in the same order**
-different compounds
Type of stereoisomer-> geometric isomers (cis-trans)
Type of Stereoisomer?
Geometric isomer:
-differ in the geometry of the groups on a double bond:
Two types of geometric isomers:
a) cis-isomers: same side
b) trans-isomers: opposite sides
What must be true for a cis-trans isomerism to exist?
there must be two DIFFERENT groups on each end of the double bond; if two of the groups are identical, this is not a cis-trans isomer
Sp3 hybridized state
Sp2 hybridized state
Sp hybridized state
6 Different types of geometry we need to know
Formal Charge: Negative Charge
1 more electron
Formal Charge: Positive Charge
1 less electron
Formal Charge: Carbon atom with three bonds
one lone pair and negative formal charge
Oxygen - Formal Charge
No FC = 2 bonds, 2 lone pairs
- FC = 1 bond, 3 lone pairs
+ FC = 3 bonds, 1 lone pair
Nitrogen - Formal Charge
No FC = 3 bonds, 1 lone pair
- FC = 2 bonds, 2 lone pairs
+ FC = 4 bonds, no lone pairs
Carbon - Formal Charge
No formal Charge = 4 bonds
- FC = 3 bonds, 1 lone pair
+ FC = 3 bonds, no lone pair
Remember:
C-H bond usually considered nonpolar
Don’t Forget:
Include the dipole moment for lone pairs! Always directed toward the lone pairs because they are the most electronegative
Is trigonal planar symmetrical?
yes
The attractive forces that cause molecules to associate into solids and liquids?
- London dispersion forces- present in all molecules
- Dipole-Dipole forces of POLAR molecules
- “Hydrogen bonds” that link molecules having -OH or -NH groups
To predict boiling points, look for differences in:
- hydrogen bonding
- molecular weight and SA
- dipole moments
When determining water solubility between two molecules that both carry -OH bonds. What could be the determining factor?
The number of carbons in the carbon chain; the fewer the number of carbons, the smaller the molecule, the more soluble the molecule
Acid base reactions favor ________
the weaker acid and the weaker base.