Organic Chemistry: Introduction
What Is Chemistry?
Chemistry Is The Study Of Matter & The Changes It Undergoes
Two Main “Branches” of Chemistry
Organic
Chemistry
• Term Coined by Berzelius ~ 1807
• Matter Derived From Living Things
• Study of Carbon Compounds (C,H,N,O)
Inorganic
Chemistry
• Matter Derived From Nonliving Things
• Vast Majority of the Periodic Table
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Influence of Organic Chemistry
Organic Chemistry Is Important to Medicine: Ancient and Modern
• Plant Extracts as Medicines…Active Ingredients are Organic Compounds
• Prescription Drugs….Prepared by “Synthetic Chemists”
Organic Chemistry and Dyes:
• 1 st Solid Link of Industry and Research
• $$ Derived From Research
Organic Chemistry and Materials Development:
• Synthetic Fibers….Nylon
• Synthetic Rubber….Neoprene
• Chemistry of Polymers (Plastics)
3

Organic Chemistry and You?
Redox Reactions
Alcohols
Aldehydes
Ketones
Alkanes/alkenes
Ethers
Carboxylic acids
Concentration
Redox Reactions
Spectrometry
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1. Atomic Structure
2. Lewis Dot Structures and Formal Charge
3. Ionic and Covalent Bonds
4. Electronegativity and Polarity
5. Molecular Geometry
6. Multiple Bonds
5

Atoms have an internal structure consisting of one or more subatomic particles: proton

positive charge mass = 1.673 x 10
-27
kg neutron

no charge mass = 1.675 x 10
-27
kg electron

negative charge mass = 9.109 x 10
-31
kg
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1

Most of the mass of an atom is concentrated in the
nucleus, which contains one or more positively charged protons and neutrons with no electrical charge.
1
7

One or more negatively charged electrons are in constant motion outside the nucleus.
What is the overall electrical charge if the number of electrons equals the number of protons?
1
8

Electrons contained in the outermost shell are called
________electrons.
All other electrons are called ______ electrons. eeeee-
How many valence electrons does this atom have? Core electrons? Which number matters more?
1
9

How many valence electrons (ve-’s) does carbon have? Calcium? What element is depicted in the image on the right?
10
1

Chemical bonds are the forces that hold atoms together in compounds. We use Lewis Dot structures to represent these atoms and compounds.
C O C O
2
11

1. Count total ve-’s available
2. Draw a Lewis sketch
– H is never central; C is often central
3. Draw in electrons to fulfill octet and duet rules
– C “likes” 8 electrons; H “likes” 2 electrons
4. Count ve-’s and compare to #2
5. If too many e-’s, make a double bond
6. Calculate formal charge (FC) to double check structure
– No or low FCs (e.g. +1) more likely than large FCs (e.g.
+2)
12
2

NH
3
2
13

Formal charge = ve-’s – (lone pairs + bonds)
In a neutral molecule, the sum of the FCs = zero. For an ion, the sum of the FCs = the charge of the ion.
2
14

1. Circle the atom of interest.
2. Count the electrons inside the circle. If the circle
“breaks” a bond, only count one electron of the bond.
3. Take the ve-’s for the atom (its group number) and subtract #2.
FC of oxygen= 6 – (6) = 0
O C O
FC of carbon= 4 – (4) = 0
2
15

Resonance structures result when more than one valid Lewis dot structure can be drawn for one molecule.
– The positions of the nuclei can’t change (C, H, etc.)
– The positions of multiple bonds or lone pairs can move
– Low FCs are still favored
2
16

Carbon
C
Nitrogen
N
Oxygen
O
Halogens
X
C N O
C
C
Four bonds
No lone pairs
N
Three bonds
One lone pair
Two bonds
Two lone pairs
One bond
Three lone pairs
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2

C rb
C
C
N itro n
N
N
N
N
N
O y n H lo s
O
X
O
O
2
18

Bonds formed by the transfer of electrons from one atom to another are __________.
Example:
Sodium chloride (NaCl)
Na  Na + + e -
Cl + e  Cl __
Na + Cl  NaCl
+ + + +
_ _ _
+
_
+
_
+
_
+
+ + + +
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3

Bonds formed by the sharing of electrons between two atoms are __________.
Example:
Glucose (C
6
H
12
O
6
)
3
20

Polar bonds are bonds between atoms created by sharing electrons unevenly.
4
H F
 
F F
Uneven sharing is the result of electron “greedy” atoms (i.e. more electronegative atoms).
21

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.
4

A polar molecule is a molecule that is electrically asymmetrical, resulting in charges at two points. The molecule is said to have a molecular dipole or dipole moment.
4
O
H H
O
H
C
H
23

Not all molecules that contain polar bonds will be polar molecules!
4
OCO
24

Common geometries:
5
25

Acetone
C
3
H
6
O
Is acetone ionic or covalent?
What its geometry?
26
PQ

 Atomic orbitals (AOs)are the probability distribution about one atomic nucleus
(found using wave functions ψ)
 AOs relate to quantum numbers
(n, l, m l
, m s
)
 Each AO can have, at most, two e-
(Pauli Exclusion Principle)
 AOs are filled with e-’s from the lowest energy to the highest
(Aufbau Principle)
 The electron configuration with the highest number of unpaired spin is more stable
(Hund’s rule)
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5

Atom
Boron
Electronic
Structure
1s
2
2s
2
2p
1
Electronic
Configuration
3 p
3 s
2 p
2 s
1 s
Lewis Dot
Structure
5
B
Phosphorus [Ne] 3s
2
3p
3
3 p
3 s
2 p
2 s
1 s
P
28

5
29

2s
1s
30
2p

5
31

When carbon double bonds, the 2s, 2p x and 2p carbon form three sp 2 hybrid orbitals. y orbitals on
The three hybrid orbitals form the points of a triangle.
C
A trigonal planar atom has sp 2 hybridization.
32

C C
The three sp2 hybrid orbitals of carbon and 1s orbitals of hydrogen make up the σ-framework of ethene.
33
6

When the double bond is formed between the two carbons of ethene, a different type of bond is needed
(a π bond). This bond is formed with the remaining
2p z orbitals and is higher energy than the σ bonds.
6
34