Exam 1 Flashcards
What is the formula for an alkane
What is the VESPR shape and bond angle
What is the hybridization
CnH2n+2
Tetrahedral, 109.5
sp3
What is the formula for an alkene
What is the VESPR shape and bond angle
What is the hybridization
CnH2n
Trigonal Planar: 120
sp2
What is the formula for an alkyne
What is the VESPR shape and bond angle
What is the hybridization
CnH2n-2
Linear; 180
sp
What does saturated vs unsaturated mean
Saturated has the max amount of H bonds, no double or triple bonds
Unsaturated has double or triple bonds that do not allow for the max number of H.
Define stereoisomers
same connectivity, rotation around C-C is restricted.
Can be cis or trans
Constitutional Isomer
Same molecular formula but different arrangements of atoms
How many bonds do each of the following typically want :
Carbon
Nitrogen
Oxygen
Halides
Carbon- 4 bonds
Nitrogen- 3 bonds (has lone pair)
Oxygen- 2 bonds (has 2 lone pairs)
Halides- 1 bond (has 3 lone pairs)
What is the typical formal charge when:
an element has an extra lone pair
an element has an extra bond
extra lone pair will be -
extra bond will be +
what is a sigma bond vs pi bond
sigma is single bond
pi bond is double bond
what is a degenerate orbital
orbitals of the same energy level.
Hybrids are degenerate.
What is the lowest energy orbital?
1s
Aufbau principle
“build up”, must start from lowest energy level before filling a higher one
Paulis exclusion principle
each orbital has opposite spins
Hunds Rule
One in each before doubling up.
What type of interference will result in a bond?
constructive interference only.
Antibonding (*) is considered destructive interference and is of a higher energy level-has a node
What makes pi bonds?
overlapping UNHYBRIDIZED orbitals
What is the longest bond?
What is the strongest bond?
longest is a single bond
strongest is a triple bond
What is the steric number for sp3 ,sp2, and sp orbitals?
sp3 =4
sp2=3
sp=2
Polar or nonpolar:
Tetrahedral with symmetry
Tetrahedral without symmetry
Bent
Trigonal Planar with symmetry
Trigonal Planar without symmetry
Tetrahedral with symmetry- nonpolar
Tetrahedral without symmetry- polar
Bent- polar
Trigonal Planar with symmetry-nonpolar
Trigonal Planar without symmetry- polar
*Be cautious of atoms with similar electronegativities
Intramolecular forces vs intermolecular forces
Intra- within the molecule. Can be Ionic or Covalent (polar non polar)
Inter-between molecules. Can be London Dispersion, Dipole Dipole, Hydrogen.
Rate the intermolecular forces weakest to strongest
LD< DD< Hydrogen
The stronger the intermolecular forces, the _________ the melting point
Why
The stronger the intermolecular forces, the HIGHER the melting point.
Its a stronger bond, will require more energy (heat) to break it
What factors can help determine order of melting point between given molecules
Greater surface area allows for stacking- increase melting point
Branching will decrease melting point
Longer chains will have increased melting points
Hydrogen bonding will have higher melting points
What does it mean when a compound is “protic”
Compounds with H atoms that are capable of forming hydrogen bonds
Which atoms are most likely to form Hydrogen bonds. Why?
F.O.N. They each have a lone pair ready for H to attach too. They are very electronegative.
Stronger ka is a _______pka, _______acidic
Stronger ka is a lower pka, more acidic
The stable base is the _______base, which comes from the ______acid
The stable base is the weaker base, which comes from the stronger acid.
When comparing acids, equilibrium will favor the ________acid
equilibrium will favor the weaker acid
ARIO
Atom- based on size then electronegativity
Resonance
Induction-based only on electronegativity
Orbital- sp is more stable
what is the pka for:
Bronsted Lowry acid/base vs Lewis acid/base
Bronsted Lowry acid donates H, base accepts H
Lewis acid accepts LP, base donates LP
Why does equilibrium favor the weak acid?
Because a strong acid will completely dissociate and go to completion. A weak acid can be slowly moved and controlled/balanced
What are the 6 strong acids to know
HCl
HI
HBr
HNO3
HClO4
H2SO4
Ka> 1
Ka<1
Which side of equi is favored?
Ka>1 favors products
Ka<1 favors reactants.
Why? Because ka=[H][A]/[HA]
Strong acids will give conjugate bases ________than water
Strong acids will give conjugate bases weaker than water
When using ARIO, what are we looking at?
the BASES!!!!
What are the 5 steps to recrystallization?
Choosing the Solvent
Dissolving the Solute
Filtering undissolved impurities
Crystallizing the solute
Collecting and washing the crystals
Recrystallization lab:
How to choose the solvent
Like dissolves like
Choose the solvent that will dissolve the solute only when you heat the mixture, not at room temp
Recrystallization lab:
_____ cooling gives the best crystals
SLOW cooling gives the best crystals
Recrystallization lab:
When do you use gravity filtration vs vacuum filtration?
Gravity is used when filtering undissolved impurities
Vacuum is used when collecting and washing the crystals
Recrystallization lab:
Describe the characteristics of a good solvent
The solid to be recrystallized is very soluble when the solvent is near its boiling temperature and only sparingly soluble when the solvent is at room temperature or below
Recrystallization lab:
What is the purpose of adding activated carbon/charcoal to a solution during recrystallization?
To remove colored impurities
Recrystallization lab:
Melting point is a ______ property and can be used to ______
Melting point is a PHYSICAL property and can be used to IDENTIFY A SUBSTANCE
Recrystallization lab:
What does it mean when a compound melts over a very narrow range? and over a wide range?
It can be assumed that the compound is relatively pure with a narrow range.
A wide melting range suggests impure.
Recrystallization lab:
What is the effect of impurities on the melting range?
Why?
Lowering the melting point and widening the range.
Impurities disrupt the organization of the pure substance.
What is chromatography
technique of separating the mixture of compounds into their individual compounds.
Chromatography Lab:
List some types of Chromatography
paper, thin layer (TLC), Liquid-liquid, gas, high performance liquid (HPLC)
Chromatography Lab:
Calculate the Rf
Retention factor = distance traveled by compound / distance traveled by solvent
Chromatography Lab:
The stronger a compound is bound to the adsorbent, the _________ is moves up the paper/silica
The stronger a compound the slower it moves
Nonpolar compounds move up the plate most rapidly
Chromatography Lab:
Mobile phase vs Stationary phase
Mobile phase is the liquid that moves the sample up the stationary phase.
Silica paper was our stationary, the Solvent was our mobile.
Chromatography Lab:
Adsorbtion
the ability of a substance to “stick” (or be adsorbed) to a surface
What is another term for spectator ions?
Counterions.
They are always present but not reacting, other than to balance charge
Acids strong than ______ cannot be used as a solvent in water. Why?
Bases stronger than _____ cannot be used in water. Why?
