Test 1

Elements in Organic Compounds

HCONSP

(Please See Her New Orange Cat - PSHNOC)

The _ contributes to most of the mass

The Nucleus contributes to most of the mass

The _ _ contributes to most of the volume

The Electron Cloud contributes to most of the volume

Orbitals

Represents location of electron in an atom

Probability maps which show a statistical distribution of where the electron is likely to be found

Atomic orbitals are denoted by __Orgo focuses on __

s, p, d, f

s, p

s orbitals are _

s orbitals are spherically symmetric

The 2s orbital has a _

The 2s orbital has a nodal surface

Electron configurations

Be familiar

2nd row elements follow the _ rule

The octet rules

Polarity is based on _

Polarity is based on differences in electronegativity between the 2 atoms in the bond

Dipole moment

Measurement of dipole

Increasing electronegativity differences _ dipole moment

Increasing electronegativity differences Increases dipole moment

Increasing the number of bonds _ dipole moment

Increasing the number of bonds increases dipole moment

Trend of electronegativity on periodic table

Electronegativity greatest in the North East

Which has greater electronegativity Cl or O

O, O>Cl

Formal charge

who owns the electrons

analysis shows us how to place charges

very strong indicator of a structure’s behavior

How to calculate formal charge

(Electrons owned by the atom) = (one electron per bond) + (all lone pair electrons)

(Formal charge) = (valance electrons) - (electrons owned by the atoms)

Positive formal charge

Less bonds than normal

Negative formal charge

More bonds than normal

Carbon stability

C - anions very unstable

C - cations very unstable

C only likes having 4 bonds

Anion

Negatively charged ions

Cation

Positively charged ion

Line drawings

a simplification of expression of the carbon skeleton

Each end and every bend in between indicate carbon atoms

Hydrogens on carbons are inferred

Only heteroatoms and their Hs are explicitly drawn

Formal charges, when present, ae ALWAYS shown explicitly

Resonance

Electron delocalization

Resonance Rules

Connectivity is remains the same (no moving single bonds)

Number of electrons and net charge is the same

Number of unpaired electrons is the same

Any structure that exceeds octet rule for 2nd row elements is invalid

Predicting the major contributor

The structure with the greater number of covalent bonds contributes more

When octet rule satisfied, the major structure has least charge separation

When octet rule satisfied, the major contributor has the negative charge on most electronegative element

Rank in order of major to minor contributors

Left most, right most, middle

Left most is the superior major contributor because of the octet rule

Right most is a close 2nd but has ion in the middle

Resonance structures

Depict the ‘limit’ of delocalization

Resonance hybrids

Reflect the average overall delocalization

Types of molecular models

a. Framework model

b. ball-and-stick model

c. Space-filling model

d. Ribbon model

Molecular geometrics are dictated by _

Orbitals

Molecular dipoles

Mutual cancelation of dipoles result in no net dipole moment

Curved arrows

Represent movement of electrons (Resonance)

Reaction mechanisms

Dissociation (heterolysis)

Bond formation (coordination)

Substitution (e.g: Substitution)

Acid-Base reactions (proton-transfer reaction)

Rules of arrows

correct arrows show movement of electrons only, Not atoms

start arrows at electron source (either a lone pair or a bond, never an atom)

point arrows to electron target (either an atom or a bond, never a lone pair)

All acids have what in common:

When they do their job, they form a less positive species, generally an anion

Strong acids form:

a stable anion (weak conjugate base)

Weak acids form:

an unstable anion (strong conjugate base)

Arrangement of 2 electron pairs

linear (180 degrees)

Arrangement of 3 electron pairs

trigonal planar (120 degrees)

Arrangement of 4 electron pairs

tetrahedral (109.5 degrees)

Molecular Geometry of an atom with 2 bonding pairs and 0 lone pairs

linear

Molecular Geometry of an atom with 3 bonding pairs and 0 lone pairs

trigonal planar

Molecular Geometry of an atom with 2 bonding pairs and 1 lone pair

bent or angular

Molecular Geometry of an atom with 4 bonding pairs and 0 lone pairs

tetrahedral

Molecular Geometry of an atom with 3 bonding pairs and 1 lone pair

trigonal pyramidal

Molecular Geometry of an atom with 2 bonding pairs and 2 lone pairs

bent or angular

Bronsted Acid

Proton donor (species with an H)

Bronsted Base

Proton Acceptor (species with a pair of electrons)

Acidity related to pKa

The lower the pKa the more acidic

In a column on the periodic table, the _ the conjugate base anion the _ the acid

In a column on the periodic table, the LARGER the conjugate base anion the STONGER the acid

Across a row in the periodic table, _ is the most accurate predictor of acid strength

Across a row in the periodic table, ELECTRONEGATIVITY is the most accurate predictor of acid strengthThe more electronegative the stronger the acid

Inductive withdrawing groups near the conjugate base anion atom _ the acidity

Inductive withdrawing groups near the conjugate base anion atom INCREASE the acidity

If the CB anion can delocalize electrons then CB is _ and the parent acid is _

If the CB anion can delocalize electrons then CB is WEAK and the parent acid is STRONG

Acid Base Reaction proceeds to form _

Acid Base Reaction proceeds to form weaker acid or base

Lewis Acid

Electron acceptor

Lewis Base

Electron donor

What are the classes of hydrocarbons?

Alkanes

Alkenes

Alkynes

Arenes

Which classes of hydrocarbons are Aliphatic?

Ethane, Ethylene, and Acetylene

Which classes of hydrocarbons are Aromatic?

Arenes

The general chemical formula for alkanes

CnH2n+2

The general chemical formula for alkenes

CnH2n

The general chemical formula for alkynes

CnH2n-2

The general chemical formula for arenes

CnH2n-6mm is number of rings

Alkanes have _ bonds

Single

Alkenes have _ bonds

double

Alkynes have _ bonds

triple

Arenes have _ bonds

Alternating double and single

Antibonding

A-B out of phase

Energy Cost

Bonding

A+B in phase

Energy saved

sp3 hybridization

Are the average of the 4 contributing orbitals and are equal in energy

Tetrahedral

sp2 hybridization

Are the average of the 3 contributing orbitals: 2s orbital and 2 of the 2 px and the 2py orbitals

Shape at centers is planar

sp hybridization

Are the average of the 2s and 2px orbitals

Constitutional isomers

Same molecular formula

Different connectivity

Different physical properties

n-alkanes

condensed structural formulae of the higher n-alkanes

CnH2n+2

Number of constitutional isomers compared to molecular formula

The number of constitutional isomers possible quickly increases with each added carbon

IUPAC name of unbranched alkanes with 1 carbon

Methane

IUPAC name of unbranched alkanes with 2 carbons

Ethane

IUPAC name of unbranched alkanes with 3 carbons

Propane

IUPAC name of unbranched alkanes with 4 carbons

Butane

IUPAC name of unbranched alkanes with 5 carbons

Pentane

IUPAC name of unbranched alkanes with 6 carbons

Hexane

IUPAC name of unbranched alkanes with 7 carbons

Heptane

IUPAC name of unbranched alkanes with 8 carbons

Octane

IUPAC name of unbranched alkanes with 9 carbons

Nonane

IUPAC name of unbranched alkanes with 10 carbons

Decane

IUPAC name of unbranched alkanes with 11 carbons

Undecane

IUPAC name of unbranched alkanes with 12 carbons

Dodecane

Steps to IUPAC Nomenclature

Find the longest continuous chain of C atoms, assign a parent name to the compound corresponding to the IUPAC names of the unbranched alkane having the same number of carbons

List the substituents attached to the longest continuous chain in alphabetical order

Use the prefixes di-, tri-, tetra, and so on when the same substituent appears more than onceIgnore these prefixes when alphabetizing

Number from the end of the chain in the direction that gives the lower locant to a substituent at the first point of difference

Alkyl groups (Primary vs Secondary vs Tertiary)

Correlates to the number of carbon attached to the carbon in question

3 common complex branch alkyl groups

Isopropyl

Tert-butyl

Sec-butyl

Another name for the complex branch alkyl group: 1-methylethyl

Isopropyl

Another name for the complex branch alkyl group: 1.1-dimethylethyl

Tert-butyl group

Another name for the complex branch alkyl group: 1-methylpropl

Sec-butyl group

Nomenclature for cycloalkanes

Same as with linear alkanes just add cycloalkane in front of parent names

Keep locant numbers low (the sum should be as low as possible)

Physical Properties of alkanes (there’s 4)

Low melting point

Poor solubility in water

Boiling point lower than analogous amines or alcohols

Boiling points change among isomers

Alkanes are amongst the _ acids known

Alkanes are amongst the WEAKEST acids known

What affects boiling point of alkanes

Stronger intermolecular attractive forces increase the boiling points

Dipole-dipole (including hydrogen bonding)

Dipole/induced-dipole

Induced-dipole/induced dipole

Combustion of alkanes

Based on stability of isomers

The less stable the greater the heat of combustion

Stability of isomers

The more branching means more stable means less energy released