Exam 1 (Chapters 1-4) - Organic Chemistry I

Organic Chemistry

The study of the structure, properties, composition, reactions, and preparation of carbon compounds

Examples of things that contain organic chemistry (5)

Proteins, DNA, amino acids, food, and medicines

Vital Force

Organic compounds could not be synthesized in a lab like inorganic compounds could

Was “vital force” proven to be true or false?

False

Who was the first person to make the distinction between organic and inorganic chemistry?

Torben Bergman

Who proved that “vital force” was false and how?

Chevreul and animal fat soap

What % of compounds contain carbon?

90%

Isotopes

Atoms of the same element that have different masses due to having different numbers of neutrons

Atomic mass = ____ + ____

Protons and neutrons

Quantum Mechanics

Describes electron energies and locations by a wave equation

ѱ means

Wave function

Wave equations yield ____ ____ which describe ____

Wave functions and orbitals

Orbitals describe…

Where an electron is most likely to be

Types of orbitals (4)

s, p, d, and f

Which two orbitals are the most important in ochem?

s and p

It takes _____ electrons to fill an s orbital

2

It takes _____ electrons to fill a p orbital, it takes ____ p orbitals to fill up a p subshell, and it takes _____ electrons to fill up a p subshell

2, 3, and 6

It takes _____ electrons to fill a d orbital, it takes ____ d orbitals to fill up a d subshell, and it takes _____ electrons to fill up a d subshell

2, 5, and 10

It takes _____ electrons to fill an f orbital, it takes ____ f orbitals to fill up an f subshell, and it takes _____ electrons to fill up an f subshell

2, 7, and 14

s orbital shape

Spherical, nucleus at center

p orbital shape

Dumbbell-shaped, nucleus at middle

d orbital shape

Flowered dumbbell-shaped, nucleus at center

Lobes of a p orbital are separated by regions of zero electron density; aka:

A node

What type of orbital is this?

2px orbital

What type of orbital is this?

2py orbital

What type of orbital is this?

2pz orbital

Ground State Electron Configuration

Lowest energy arrangement of an atom’s orbitals

What geometrical shape does carbon usually make?

Tetrahedron

Chemical Bonding Theory

Atoms form bonds to be more stable

Polar covalent bonds have…

Partial charges

Covalent bonds ____ electrons

Share

Valence Bond Theory

Electrons are paired in the overlapping orbitals and are attracted to nuclei of both atoms

This number is the same when bonds are formed and broken

Bond strength

Short bonds are ____ and longer bonds are ____

Stronger and weaker

Are pi bonds or sigma bonds weaker?

Pi bonds are weaker

Bond length ____ as the amount of bonds ____

Decreases and increases

Large parts of a molecule __ ___ ____ ____

Do not often react

General Rules of Drawing Skeletal Structures (3)

Carbon atoms are not usually shown, H atoms bonded to C atoms are not usually shown, and atoms other than C and H are always shown

If nuclei are too close…

The atoms repel back

If nuclei are too far…

The bonding is weak

A is where nuclei are…

Too close

B is where nuclei are…

Too far

B is the…

Bond length

sp^3 bond angle (º)

109.5

Tetrahedral angle (º)

109.5

109.5º is the bond angle of ____(orbital) and ____(molecular geometry)

sp3 and tetrahedral

sp^2 bond angle (º)

120

Trigonal planar angle (º)

120

120º is the bond angle of ____(orbital) and ____(molecular geometry)

sp2 and trigonal planar

sp³ has what type of bonds?

All single/sigma bones

sp² has what type of bonds?

Three single/sigma bonds and one double/pi bond

sp has what type of bonds?

Two single/sigma bonds and two double/pi bonds

sp bond angle (º)

180

Linear angle (º)

180

180º is the bond angle of ____(orbital) and ____(molecular geometry)

sp and linear

Molecular Orbital (MO)

Where electrons are most likely to be found in a molecule

Single bonds with tetrahedral geometry have _______ (orbital)

Four sp3 hybrid orbitals

Double bonds with trigonal planar geometry have _______ (orbital)

Three sp2 hybrid orbitals and one unhybridized p orbital

Triple bonds with linear geometry have _______ (orbitals)

Two sp hybrid orbitals and two unhybridized p orbitals

Hybrid Orbitals

Mixes of different atomic orbitals on a single atom

Formal charge (FC) =

Valence electrons - (bonds + lone pairs)

Set of bonds for an element when there is a positive formal charge…

Amount of bonds after taking away an electron

Set of bonds for an element when there is a negative formal charge…

Amount of bonds after adding an electron

Set of bonds for an element when there is no formal charge…

Amount of bonds the element usually forms

How many bond groups for sp³? What bonds are present?

Four, all single bonds

How many bond groups for sp²? What bonds are present?

Three, one double bond present

How many bond groups for sp? What bonds are present?

Two, one triple bond present OR two double bonds present

Bronsted Acid (BA)

Donates a proton

Bronsted Base (BB)

Accepts a proton

Lewis Acid (LA)

Accepts a pair of electrons

Lewis Base (LB)

Donates a pair of electrons

If something is a Lewis base it is also…

A Bronsted base

If something is a Bronsted base it is also…

A Lewis base

Electronegative Atoms

NOF

Rank ionic bonds, covalent bonds, and polar covalent bonds by ionic character from least to most

Covalent bonds, polar covalent bonds, and ionic bonds

Electronegativity (EN)

Ability of an atom to attract the shared electrons in a covalent bond

Difference in nonpolar covalent bond ENs

Similar ENs

Difference in polar covalent bond ENs

Less than two

Difference in ionic bond ENs

More than two

Inductive Effect

Shifting of electrons in a bond in response to EN of nearby atoms

Electrostatic Potential Maps

Show calculated charge distributions

Which way do bond polarity arrows go?

From positive (tail) to negative (head)

Dipole Moment

Net molecular polarity due to summed charges difference

μ

Magnitude of charged, Q, at the end of a molecular dipole x the distance, r, between charges

Carbanion

-1 FC

Carbocation

+1 FC

Carbonradical (unpaired electron)

0 FC

Carbene (lone pair present)

0 FC

Resonance =

Delocalization

Resonance/Delocalization

Multiple structures for the same formula that have spread out charges

What type of bonds do resonance hybrids create?

½ bonds

Resonance hybrid

A structure with resonance forms that does not alternate between forms

Rules for Resonance Forms (6)

Individual forms are imaginary, the real structure is a hybrid, forms only differ in the placement of their double bonds or nonbonding electrons, different forms do not have to be equivalent, octet rule generally applies, and a hybrid form is more stable than any individual form

Negative charges in resonance structures tend to stay with…

The most electronegative atom

Allylic Carbon

A carbon that sits directly next to a carbon with a double bond to a different carbon

These are…

Allylic carbons

Adding _____ makes more resonance structures

Double bonds

Do sigma bonds ever break in resonance structures?

No

Do pi bonds ever break in resonance structures?

Yes, they are the only bond that changes

Isomers

Molecules or ions that share the exact same molecular formula but have differing arrangements