Organic Chemistry 1

Question 1

What is the structure of a carbon atom?

Answer 1

A carbon atom has 2 shells, and is comprised of 6 protons/neutrons and 6 to 7 neutrons; with 4 electrons in the valence shell.

Question 2

What is the Octet Rule?

Answer 2

A chemical rule that reflects the theory that main-group elements tend to bond in a way that each atom has eight electrons in its valence shell.

Main group elements: Groups 1, 2, and 13 to 18

Question 3

What is the difference between the structural and the skeletal formula?

Answer 3

A structural formula uses lines to show the bonds, while the skeletal shows covalent bonds excluding hydrogen.

Question 4

What are heterolytic and homolytic cleavage?

Answer 4

Homolytic cleavage is the decomposition of a compound into two uncharged atoms or radicals.
Heterolytic cleavage involves the decomposition of a compound into two charged atoms or radicals.

Question 5

what is the difference between saturated and unsaturated O.C?

Answer 5

A molecule saturated has all sigma bonds a molecule unsaturated has double or triple bonds.

Question 6

what are some functional groups?

Answer 6

Carbonyl:   RCOR' 
Hydroxyl:    ROH
Aldehyde:   RCHO
Alcohols:   -OH
Carboxylic acid: CO2H
Esters: CO2R 
Amines:  NH2
Ketone: RC(O)R
Amide:  RC(O)NHR
Ether:  ROR

Question 7

What is Entropy?

Answer 7

Entropy is a property that measures the randomness of molecules. Represented as ΔS=ΔQ/T. Unit of measurement being JK−1.

Question 8

What is a Brønsted base and

Brønsted acid?

Answer 8

The Brønsted theory labels an acid as a proton donor and a base is a proton acceptor. A compound will be a proton donor if the compound readily dissociates to give a hydrogen ion and a conjugate base. If the conjugate base is very weak (a very stable species), then dissociation is favored and the compound is considered an acid. Brønsted acids tend to donate H+, whereas Brønsted bases accept H+.

Question 9

What is Enthalpy?

Answer 9

Is the sum and flow of the internal energy system. Represented as ΔH=ΔE+PΔV. Unit of measurement being Jmol−1.

Question 10

What categorizes compounds as a Lewis base and Lewis acid?

Answer 10

A Lewis acid is a species that accepts an electron pair while a Lewis base is a species that donates an electron pair.
In this Lewis acid‑base association reaction, the oxygen atom donates an electron pair to boron to form the new bond.

Question 11

Electrophile and Nucleophile

Answer 11

An electrophile is a molecule or substance that has a tendency to attract electrons.
A nucleophile is a molecule or substance that has a tendency to donate electrons.

Question 12

What is Markovnikov’s rule in relation to the addition of Alkenes?

Answer 12

Hydrogen is added to the carbon with the most hydrogens and the halide is added to the carbon with least hydrogens

Question 13

What is the resonance theory?

Answer 13

Theory where the actual normal state of a molecule is represented by a combination of several alternative distinct structures rather than a single valence-bond structure.

Question 14

How do you Identify the oxidation state of Carbon in a compound?

Answer 14

If the atom is more electronegative than carbon it contributes +1
If the atom is less electronegative than carbon it contributes to -1
If the atom is another carbon atom it contributes 0 to the oxidation number

Question 15

What are the three steps in a free radical substitution?

Answer 15

The first step is initiation. This step results in the formation of initial radicals. Propagation is the second step in the reaction and in this step a carbon radical is created and a product is formed. The final step is termination which involves the killing/termination of the radical.

Question 16

What are intermolecular forces?

Answer 16

The forces of attraction between atoms, covalent molecules, and ions when they are placed close together.

Question 17

3 types of intermolecular forces.

Answer 17

London dispersion forces - the weakest intermolecular force
dipole-dipole interaction - the partial charges formed within one molecule are attracted to an opposite partial charge in a nearby molecule.
hydrogen bonding - a primarily electrostatic force of attraction between a hydrogen atom covalently bound to a more electronegative atom

Question 18

What s the difference between intramolecular and intermolecular forces?

Answer 18

intramolecular hold the molecule together, while intermolecular is an attraction between molecules.

Question 19

What is aromaticity and what are the conditions related to it?

Answer 19

Aromaticity is described as a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. 
Conditions for aromaticity include:
4n+2 rule for electrons
Structure must be cyclic
Structure must be close to flat

Question 20

What is Infrared Spectroscopy?

Answer 20

The study of the interaction of energy with matter, which can be used to elucidate the structure of a molecule.

Question 21

What is a Acid–Base Reactions?

Answer 21

A process in which one or more hydrogen ions are exchanged between species that may be neutral

Question 22

What is heterolysis and what causes it?

Answer 22

It is the breakage of a single bond with the two electrons in the bond distributed unequally between the two atoms bound by the bond, it is caused by very strong solvation of the transition state.

Question 23

What is Equilibrium Constant?

Answer 23

The ratio between the amount of reactant and the product which is used to determine chemical behaviour of a chemical reaction.

Question 24

What is Standard Free-Energy Change?

Answer 24

a measure of how far the standard state is from equilibrium. standard conditions are temp: 298K, pressure: 1atm, and solutes at 1M concentration.

Question 25

How is hybridization of an atom determined?

Answer 25

The number of groups surrounding the atom is the same as the number of hybrid orbitals formed. Four 𝑠𝑝3 hybrid orbitals form from one 𝑠 and three 𝑝 orbitals. An 𝑠𝑝3 hybridized atom has four groups surrounding it. Three 𝑠𝑝2 hybrid orbitals form from one 𝑠 and two 𝑝 orbitals, and three groups surround the atom. Two 𝑠𝑝 hybrid orbitals form from one 𝑠 orbital and one 𝑝 orbital, and two groups surround the atom.

Question 26

Name 4 Basic Principles.

Answer 26

1. matter is anything that takes up space.
2. proteins break down and build structures, do all of the work in the body.
3. solid atoms are tightly packed, maintain shape, and move slowly.
4. fat stored energy, protect and insulate.

Question 27

Definition of Molecular geometry

Answer 27

Molecular geometry is the 3-dimensional shape that a molecule occupies in space. It is determined by the central atom and the surrounding atoms and electron pairs. The shape of most molecules can be predicted using the Valence Shell Electron Pair Repulsion (VSEPR) method.

Question 28

Characteristics of different molecular geometries with degree bond angles over 100:

Answer 28

Linear:
2 Bonds, 0 Lone Pairs, 180 degree bond angle, AB2 Type
Trigonal Planar:
3 bonds, 0 lone pairs, 120 bond angle, AB3 type
Bent/V Shaped:
2 bonds, 1 lone pair, slightly less than 120 bond angle, AB2E type
Tetrahedral:
4 bonds, 0 lone pairs, 109.5 bond angle, AB4 type
Trigonal Pyramidal:
3 bonds, 1 lone pair, 107 bond angle, AB3E type
Bent/V-Shaped:
2 bonds, 2 lone pairs, 104.5 bond angle, AB2E2 type
Trigonal Bipyramidal:
5 bonds, 0 lone pairs, 120 in plane; 90 perpendicular to plane bond angle, AB5
Seesaw:
4 bonds, 1 lone pair, complex bond angle, AB4E type
Linear:
2 bonds, 3 lone pairs, 180 bond angle, AB2E3 type

Question 29

Characteristics of different molecular geometries with degree bond angles less than 90:

Answer 29

Square Pyramidal:
5 bonds, 1 lone pair, about 90 bond angle, AB5E type
Square Planar:
4 bonds, 2 lone pairs, 90 bond angle, AB4E2 type
Octahedral:
6 bonds, 0 lone pairs, 90 bond angle, AB6 type
T-shaped:
3 bonds, 2 lone pairs, about 90 bond angle, AB3E2 type

Question 30

What is conformational analysis?

Answer 30

the study of the energetics between different conformations and is useful for understanding the stability of different isomers by taking into account the spatial orientation and through-space interactions of substituents.

Question 31

What are the rules of polarity?

Answer 31

1. must have 1 or more polar bonds

2. the molecular geometry doesn’t neglect polarity.

Question 32

How to determine if a bond is polar or not?

Answer 32

Determine the ∆EN between the atoms that are bonded and determine the bond dipole moments.

Question 33

What is a dipole moment and what is the equation?

Answer 33

Dipole moments occur when there is a separation of charge.

equation: u = q∙r

Question 34

What are the steps to determine polarity?

Answer 34

1. draw Lewis structure
2. determine if the molecule contains polar bonds
3. determine if the polar bonds add together to form a net dipole moment

Question 35

Bicyclic and polycyclic alkanes:

Answer 35

There are many cyclic alkanes in which two or more rings share two or more carbon atoms. These compounds are called polycycles. The molecular formula of polycycles depends on how many cycles the structure has. Bicycles in its simplest formula is CnH2n-2 since a pair of hydrogens must be lost to close each cycle. For polycycles with more than two fused cycles, the formula will be equal to that of the alkanes minus one pair of hydrogens for each cycle formed.

Question 36

Types of alkanes:

Answer 36

Depending on the connectivity between carbon atoms, alkanes can be:
Linear
Branched
Cyclic (cycloalkanes)
Bicyclic or polycyclic alkanes
Spirans

Question 36

What is a Sigma bond?

Answer 36

A sigma bond is a covalent bond formed by the overlap of atomic orbitals. This is called head overlapping or axial overlapping. Any of the following types of combinations of atomic orbitals may form this.
s-s, s-p, p-p overlapping

Question 37

What is a Pi bond?

Answer 37

Pi bonds are formed through the lateral overlap of the half - filled atomic orbitals. For pi bonds, two pure (i.e., unhybridised) orbitals are always alternating orbitals. Pi-bond always exists along with bonding to sigma.

Question 38

Why the charge of molecules change in a reaction?

Answer 38

In a reaction, the nucleophile loses or donates electrons to the electrophile so its charge increases by 1. The electrophile accepts electrons from the nucleophile so its charge decreases by 1.
The overall charge of the reaction must be the same in the products as it was in the reactants.

Question 39

What are the curved arrows used to express chemical reactions?

Answer 39

The curved arrows have a head and a tail for showing the flow of electrons from high electron density to a low electron density center. The arrow must start from the middle of a lone pair or a covalent bond. If we started the arrow from a π bond, then that would indicate breakage of the π bond. There are two main areas where curved arrows are used. The first one is their use is resonance structures and the second is their use in demonstrating the mechanisms of organic reaction.

Question 40

What do different reaction arrows mean?

Answer 40

The right arrow is the most common arrow and it points in the direction of the reaction. If the arrow were reversed, the products would become reactants.
The double arrow denotes a reversible reaction. The reactants become products and the products can become reactants again using the same process.
Two arrows with single barbs pointing in opposite direction show a reversible reaction when the reaction is at equilibrium.
These arrows are used to show an equilibrium reaction where the longer arrow points to the side the reaction strongly favors.
The top reaction shows the products are strongly favored over the reactants. The bottom reaction shows reactants are strongly favored over the products.
The single double arrow is used to show resonance between two molecules.