Quiz 1 Flashcards
Why do most elements want to reach a full octet?
So they can be stable, anything less can be reactive
How many bonds does H O N C form respectivley?
1 2 3 4
formal charge =
of valence e- (number of nonbonding e + 1/2 number of bonding e)
electronegativity
an atoms ability to attract electrons
increases across and up the periodic table (towards fluorine)
what forms dipole moments?
the partial charges formed when atoms shared electrons in polar covalent bonds
Rules of bond line structure
- all corners or end points in the lines are a carbon
- H are not drawn, its is assumed that all C have enough H to be stable
- triple bonds are drawn linearly not in the zig zag formation
What is the strongest intermolecular force?
hydrogen forces
What does a hydrogen need to be bonded to to have hydrogen intermolecular forces?
N O F
Name three intermolecular forces
- hydrogen forces
- dipole dipole interactions
- dispersion forces
How can branching affect bp solubility, state of matter, density, etc?
it changes the surface area
no branching= larger surface area
branching = smaller surface area
the — is the reason for bonding
electron
Constructive interference
creates bonding MO, lower E than antibonding MO
Destructive interference
creates a higher E antibonding MO + a node
bc the waves do not have effective overlap
MO theory
True or false? If you start with 8 orbitals before hybridization you will end with 4 after hybridization?
false, orbitals are conserved in MO theory
HOMO
highest (energy) occupied molecular orbital
LUMO
lowest (energy) unoccupied molecular orbital
sp3 hybridization
The averaging of one 2s orbital with three 2p orbitals to explain tetrahedral geometry
- creates 4 sp3 orbitals, 0 p orbitals unaffected
- single bonds
- 109.5 bond angles
sp2 hybridization
the averaging of 1 2s orbital with 2 2p orbitals to explain trig. planar geometry
- 3 sp2 orbitals, 1 p orbital unhybridized
- 1 pi bond 1 sigma bond
- 120 bond angles
Sp hybridization
the averaging of 1 2s orbital with 1 p orbital to explain linear geometry
- 2 sp orbitals, 2 p orbital unhybridized
- 2 pi bonds 1 sigma bond
- 180 bond angles
sigma bond
formed by the overlap of hybridized orbitals
all single bonds are sigma bonds
pi bonds
formed by the side to side overlap of unhybridized p orbitals
double and triple bonds
Functional group
a group of atoms that reacts the same way each time, because they are predictable they are used as classifications
describe an alkane
a single bond structure
describe an alkene
a double bond structure
describe an alkyne
a triple bond structure
describe an amine
N + H and another group/molecule
describe a ketone
double bonded oxygen onto a c-c chain
describe an alcohol
OH
describe a thiol
like an alcohol but with S instead of O
describe an alkyl halide
single bond with a halogen on the other end
If an O has a = charge how many bonds and lone pairs does it have?
two bonds, two lone pairs
if an O has a - charge how many bonds and lone pairs does it have?
one bond, three lone pairs
An O has three bonds and one lone pair, what is its charge?
positive
If a N has a = charge how many bonds and lone pairs does it have?
three bonds, one lone pair
If a nitrogen has two bonds and two lone pairs what is its charge?
negative
If a nitrogen has a + charge how many bonds/ lone pairs does it have?
four bonds, zero lone pairs
Carbocation
a carbon with three bonds and no lone pairs, sp2
MAD UNSTABLE
Carboanion
a carbon with three bonds and one lone pair, sp3
Resonance
Used to represent the distribution of e- through a molecules pi orbitals
important for stability
e- that participate in resonance, aka are unhybridized
delocalized electrons
e- that do not participate in resonance, aka are hybridized/attatched to atom
localized electrons
If an atom has a lone pair and a pi bond will the lone pair likely be localized or delocalized
likely localized bc only one or the other can participate in resonance
Name the three rules of resonance structures
- NEVER push towards an sp3 atom, they are roadblocks
- NEVER expand an octet, the atoms can have less but not more
- NEVER break a single bond
Allylic positions
positions that are adjacent, not attatched to the pi bond
Name the five patterns of resonance
- allylic lone pairs
- allyic positive charge
- lone pairs adjacent to a positive charge
- a pi bond between atoms of differing electron negativity
- conjugated pi bonds in a ring
Name the three rules of determining the significance of a resonance structure
- The most significant model will be one that has all filled octets (aka a neutral molecule)
- The most significant contributor will be one that has the fewest formal charges
- The most significant contributor will be one that has a charge on the more electronegative atom
