Exam 1 Flashcards
Ionic Bond
Metal Atom + Non-metal Atom, Transfer of electrons
Covalent Bond
Two Non-Metal Atoms, Sharing of Electrons
Perfect Covalent Bond
Two Identical Atoms
Polar Covalent Bond
Imperfect Sharing of Electrons, Partial Positive end and a Partial Negative end
Electronegativities
The closer the EN value between two electrons, the stronger the bond is
Lewis Structure
2-D representation of the connection between atoms
Octet Rule
- 2nd row elements (C,N,O,F) = 8e-
- Hydrogen = 2e-
- 3rd row elements = (typically) 8e-
Exceptions: - B and Al do not require an octet
- S and P can have extended octets
Decrease of Unsaturation
U = (n(C) + 1) - 1/2(n(H) + X - n(N))
X = Halogens
of Valence e-
EX: C2H6O = 2(4) + 6(2) + 1(6) = 20e-
Formal Charge
Natural Bonding Pattern of an Atom
FC = (# Valence e-) - (Bonds + Lone e-)
Carbocation
Carbon with a positive formal charge
Carboanion
Carbon with a negative formal charge
Radical
a single unpaired electron
Resonance
The movement of electron to make or break double bonds to satisfy multiple unbalanced formal charges
Highest Contributing Resonance Form
- All atoms have an Octet
- Fewest Formal Charges
- The atom carrying the FC is the most stable option
Bronsted Lowery Acid
Accepts e- (Donates a H+)
Bronsted Lowery Base
Donates e- (Accepts H+)
Common Strong Acids
H2SO4, HNO3, H3PO4
Acid Base Equilibrium Direction
Strong acid/base compounds react to make weak acid/base compounds - More than one trend shown leads you to look at the PKA
Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Periodic trends
Larger atoms hold a negative charge better
Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Electronegativity
Acid - the more electronegative atom is the stronger acid, more likely to stably hold extra electrons
Base - the more electronegative atom is the weaker base, wants to hold onto the electrons it has.
Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Atom Size
Applies to atoms in the same column Larger atoms can hold the extra electrons over a larger area
Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Induction
Distance of the most electronegative atom to the acidic hydrogen - The closer the electronegative atom is to the hydrogen the more pull it has on the electrons, thus weakening the O-H bond
Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Hybridization
Electron density - Acidity = sp > sp2 > sp3
Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Resonance
The more available resonance structures the weaker the base - electrons are shared across multiple atoms making it more stable
Equilibrium Direction (acid vs conj. acid or base vs conj. base) - pKa Values
Lower the pKa the more acidic - used when more than one acid/base indicator is present
Electrophile
Accepts e- (Acid)
Nucleophile
Accepts a H+ (Base)
Molecular Orbitals
Combination of atomic orbitals - # of atomic orbitals = # of molecular orbitals
Bonding orbitals
Cunstructive/ Forms
Anti-Bonding orbitals
Destructive/ Breaking
Hybridization - sp3
sp3 -> 4 sp3 orbitals
Hybridization - sp2
3 sp2 -> 3 sp2 orbitals + 1 empty p orbital
Hybridization - sp
sp -> 2 sp orbitals + 2 empty p orbitals
Special Derivatives - Methyl
Methyl Cation (sp2) - 3sp2 orbitals with an empty p orbital
Methyl anion (sp3) - 3 sp3 orbitals with a lone pair in a p orbital
Methyl Radical (sp2) - 3 sp2 orbitals with one e- in the p orbital
Physical Properties of Polarity
BP, MP, and solubility are all determined by the dipole moment of the compound - stronger dipoles increase the energy needed to separate molecules from one another
Intramolecular forces
Within a compund
Intermolecular forces
Between molecules
Atractive Forces
A. Charge - Charge, solids
B. Charge - Dipole, Solutions
C. Dipole - Dipole, polar liquids
D. Induced Dipole - Dipole, non-polar liquids
Dipole - Dipole interaction
partial positives and partial negatives within a molecule interact with surrounding molecule’s partial positives and partial negatives
Structural Isomers
made up of the identical atoms in a different arrangement - physical properties change
Induced dipole - dipole interactions (LDF)
Temporary interactions created when non-polar molecules interact with one another - allows non-polar molecules to exist close together
Shape’s affect on boiling point
The more surface area a molecule has the higher the boiling point - the more LDF’s that can be formed
Bond Rotation
only single bonds can rotate freely - double bonds are fixed
Isomerism
Different compounds with the same molecular formula
Structural isomers
Same molecular formula but different connectivity
Stereoisomers
Atoms connected in the same sequence but arranged differently in space - Cis/Trans isomers
Wave number
identifies what bond is vibrating at that wavelength
Finger print region
less than 1400 - unreliable
Alkane sp3, R-C-H
Aprox. 2800 - 3000
Alkene sp2, R=C-H
R=C-H Aprox. 3000 - 3100, C=C Aprox. 1640
Alkyne sp
=_ C-H Aprox. 3300, C=_C-H Aprox. 2100
Alcohols
Parabola Aprox. 3300
Amines
N-H wide spike Aprox. 3300, NH2 double spike Aprox. 3300
Ketone
C=O spike Aprox. 1700, no twin peak and no parabola
Aldehyde
C=O spike Aprox. 1700 and twin beak C-H Aprox. 2700 and 2800
Carboxylic Acid
Parabola with spikes out of the bottom Aprox. 3300 and C=O Aprox. 1700
Amide
C=O Aprox. 1640-1680 and NH Aprox. 3300
Nitriles
C=_N Aprox. 2200
Esters
C=O Aprox. 1740 and C-O Aprox. 1100-1200
Benzene
peak Aprox. 1600
Mass Spec
M+ or M2+ can determine the compound with its mass
Mass spec - Amines
odd M+
Mass spec - Bromine
Twin peaks
Mass spec - Chlorine
3/1 ratio M+/M2+
Mass spec formula only C-H
M+ - ((M+/13)x12) = Hydrogens
