- 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

Exam 1 Flashcards by Chloe Carbonneau

Ionic Bond

Metal Atom + Non-metal Atom, Transfer of electrons

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Covalent Bond

Two Non-Metal Atoms, Sharing of Electrons

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Perfect Covalent Bond

Two Identical Atoms

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Polar Covalent Bond

Imperfect Sharing of Electrons, Partial Positive end and a Partial Negative end

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Electronegativities

The closer the EN value between two electrons, the stronger the bond is

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Lewis Structure

2-D representation of the connection between atoms

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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

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Decrease of Unsaturation

U = (n(C) + 1) - 1/2(n(H) + X - n(N))
X = Halogens

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of Valence e-

EX: C2H6O = 2(4) + 6(2) + 1(6) = 20e-

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Formal Charge

Natural Bonding Pattern of an Atom
FC = (# Valence e-) - (Bonds + Lone e-)

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Carbocation

Carbon with a positive formal charge

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Carboanion

Carbon with a negative formal charge

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Radical

a single unpaired electron

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Resonance

The movement of electron to make or break double bonds to satisfy multiple unbalanced formal charges

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Highest Contributing Resonance Form

All atoms have an Octet
Fewest Formal Charges
The atom carrying the FC is the most stable option

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Bronsted Lowery Acid

Accepts e- (Donates a H+)

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Bronsted Lowery Base

Donates e- (Accepts H+)

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Common Strong Acids

H2SO4, HNO3, H3PO4

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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

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Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Periodic trends

Larger atoms hold a negative charge better

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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.

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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

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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

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Equilibrium Direction (acid vs conj. acid or base vs conj. base) - Hybridization

Electron density - Acidity = sp > sp2 > sp3

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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