Transcript FSN 1500 Week 7 - Oakland Community College

FSN 1500 Week 7
Organic Compounds, the
Periodic Table and Related
Topics
Organic Compounds
Organic compounds - carbon-containing
compounds where carbon forms the
structural framework of the molecule
 Remember: to our knowledge all life on
Earth is organic compound based!
 Millions of organic compounds exist;
organic compounds are over 10X more
abundant than all inorganic compound
types combined
 Why are there so many organic
compounds if carbon atoms comprise only
0.02% of crustal elements by weight?

Organic Compounds
Organic compounds are so abundant
because carbon can bond to other atoms
by a variety of mechanisms, has a small
atomic volume and tends to form strong
covalent bonds in organic molecules
 Organic compounds are classified into a
variety of categories; the simplest organic
compounds are the hydrocarbons

Organic Compounds (Hydrocarbons)


Hydrocarbons compounds containing
different ratios of
hydrogen and carbon
atoms
The methane series of
hydrocarbons (see
figure) contains many
useful fuel gases,
gasoline, kerosene
and waxes
The methane series of hydrocarbons
Organic Compounds


All organic
compounds can
have their molecular
structures
represented through
Lewis Structures
The line segment
between atoms
represents a single
covalent bond (one
pair of electrons
shared)
Butane (C4H10)
Lewis Structure Diagram
Organic Compounds
Lewis Structures provide insight into the
physical and chemical behavior of a
compound (remember: a compound’s
properties are dictated by its composition,
type of bonding and bond orientation)
 Isomers - organic chemical compounds
with the same formula but different
molecular structures; the different
structures result in different properties!
(see figure)

Isomers – organic chemical
compounds with the same
chemical formula but different
molecular structures.
Note how the different
structures results in
different properties for
the isomers.
Organic Compounds (Hydrocarbons)
Hydrocarbons can be subclassified into
alkane, alkene and alkyne families
 Alkane hydrocarbons host single electron
pair covalent bonds between atoms sometimes referred to as saturated
hydrocarbons; all alkanes have the
generic formula (CnH2n+2) (see figure)
 The more saturated the compound the
less chemically reactive it is (e.g.,
saturated fats)

Alkane Hydrocarbons
Organic Compounds (Hydrocarbons)

Alkene hydrocarbons - category of
hydrocarbons that share the general
formula CnH2n (e.g., C2H4 - ethylene gas);
these possess at least one double covalent
bond (two electron pairs shared) between
adjacent carbon atoms (see figure)
Alkene Hydrocarbons
note the double covalent bond
Organic Compounds (Hydrocarbons)
Alkyne hydrocarbons - category of
hydrocarbons that share the general
formula CnH2n-2 (e.g., C2H2 - acetylene
gas); these possess at least one triple
covalent bond (three electron pairs
shared) between adjacent carbon atoms
(see figure)
 Alkanes are saturated hydrocarbons, the
alkenes and alkynes are unsaturated and
more chemically reactive

Alkyne Hydrocarbons
Why are the alkenes and alkynes more chemically reactive than the
alkanes? Think about the relative length and strength of the covalent
bonds in these compounds.
Bond Length and Bond Strength
Comparison for a Single Covalent Bond
Covalent Bond A
N
Covalent Bond B
N
N
Bond Length
N
Bond Length
N = atomic nucleus
The longer the bond length the weaker the bond.
Butane
Acetylene
The bond length of the single covalent bonds in
Acetylene is longer, and therefore weaker, than the
bond length of the single covalent bonds in Butane
Organic Compounds (Hydrocarbons)
Aromatic hydrocarbons - category of
pleasant smelling unsaturated
hydrocarbons with structures derived from
that of the benzene ring (C6H6 - see
figure)
 Many aromatic hydrocarbons are toxic or
thought to be carcinogenic even in small
amounts (e.g., PBB - polybrominated
biphyenl, PCB - polychlorinated biphyenl)

Polychlorinated Biphenyls
Two benzene rings bonded together = a
“biphenyl”
Organic Compounds (Hydrocarbons)

Aromatic hydrocarbon
contamination of
public water supplies,
soil, fish and other
natural resources is
common in most
industrial areas since
the aromatic
hydrocarbons or their
byproducts are
common in industrial
products or their
wastes
Many older electrical transformers contain
PCBs in the electrical insulating fluids
Organic Compounds (Alcohols)

Alcohols - organic
compounds similar
to the
hydrocarbons, but
one or more of the
H atoms is
replaced by an
hydroxide (OH)
group (see figure)
Organic Compounds (Alcohols)
H
H
C
OH
H
Methanol
H
H
H
C
C
H
H
Ethanol
OH
Organic Compounds (Alcohols)
The OH group is called a “functional
group”; functional groups are the chemical
constituents that most determine the
properties of that substance
 Example: What’s the only Lewis Structure
difference between methane (CH4 hydrocarbon) and methanol (CH3OH alcohol)?

Organic Compounds (Organic Acids)
Organic acids - organic compounds that
generate acidic solutions; the functional
group for these compounds is the carboxyl
group (COOH); acetic acid (the acid of
vinegar) is an example; see figure
 Organic acids are produced from decaying
organic matter and may be important
agents of chemical weathering

Organic Compounds (Fats)
Fats - organic compounds that belong to a
broader category called esters; esters are
formed by the reaction between an alcohol
and an acid (see figure)
 Solid fats are saturated; the fats in liquid
oils are technically unsaturated - be
careful: some cooking oils have small
particles of solid fat blended into them

Organic Compounds (Fats)
Why do nutritionists advise that our fat
intake is low (< or = 30% of caloric
intake) and that we limit our intake of
saturated fats?
 What is hidden in the terms “partially
hydrogenated oil ” and trans-fatty acids?
 What is the controversy surrounding
trans-fats in the food supply and what
recent legal actions illustrate the
importance of this topic for the layperson?

Organic Compounds (Fats)


What is hidden in the
terms “partially
hydrogenated oil ” and
trans-fatty acids?
What is the controversy
surrounding trans-fats in
the food supply and what
recent legal actions
illustrate the importance
of this topic for the
layperson?
Organic Compounds (Carbohydrates)


Carbohydrates - organic compounds whose formulas look
like they contain carbon united with water ; consist of C, H,
and O atoms with H atoms twice, or nearly, the number of
O atoms
There are many carbohydrates; they’re generally classified
as “simple” – relatively few atoms per molecule (e.g.,
glucose - C6H12O6 and other sugars) or “complex” (perhaps
dozens to thousands of atoms per molecule) (see figure)
Organic Compounds (Carbohydrates)
Complex carbohydrates may contain
hundreds of atoms per molecule - these
include starches found in foods like rice,
potatoes, oatmeal, etc.
 Why do nutritionists advocate that our
diets be based on complex carbohydrates,
not simple carbohydrates?

Organic Compounds (Carbohydrates)
The aerobic decomposition of
carbohydrates in our body is a primary
energy producer: CH2O(s) + O2(g) --->
CO2(g) + H2O + energy
 Proteins - organic compounds that contain
the amino (NH2) functional group and
usually a little sulfur or phosphorous
 Proteins are constructed by the linking of
amino acids (organic acids containing the
amino group) into chains (see figure)

Organic Compounds (Proteins)
Some proteins may be composed of chains
containing tens of thousands of amino
acids
 Nutritionists often refer to essential
(supplied by our diet) and non-essential
(manufactured in the body) amino acids;
proteins are involved in nearly every
biological process

The Periodic Table
Chemists of the eighteenth and nineteenth
century noticed that certain elements
(e.g., Au, Ag, Cu or He, Ne, Ar) exhibited
similar chemical behavior
 Mendeleev (Russian) and Meyer (German)
proposed that the chemical behavior of
elements was a periodic (recurring)
function of their atomic masses

The Periodic Table
Mendeleev published one of the first
periodic tables in 1872 (see figure)
 Mendeleev and Meyer didn’t have
knowledge of subatomic structure - their
ideas were subsequently modified

The Periodic Table



Modern Periodic Law - the chemical behavior of
the elements is a periodic function of their atomic
number
We now know that the electron distribution
around the nucleus controls the atom’s chemical
behavior. In an uncharged atom what controls
the number of electrons? The number of protons
(atomic number) in the nucleus.
The modern periodic table is arranged into an
array (series of rows and columns) of increasing
atomic number elements
The Periodic Table
The rows of the periodic table are called
periods; the columns are called families or
groups (see figure)
 All the members of a group have the same
outermost energy level electron
distribution pattern - the reason for their
similar behavior
 Metals are the most abundant elements ;
the true nonmetals lie toward the far and
upper right of the table

The Periodic Table
A few elements (e.g., As, Po) are called
metalloids - they have properties of both
metals and nonmetals
 Across a period (left to right) the
properties of the elements trend from
strongly metallic to strongly non-metallic
with the last member of each period a
noble gas

The Periodic Table
Brief Overview of Some Groups:
 Noble Gases (VIIIA) - all have the electron
distribution required for energetic stability
and therefore have no tendency to
chemically react
 Halogens (VIIA) - all need one electron to
complete their energy stability
requirements; hal - salt, gen - genesis

The Periodic Table
The halogens commonly react with
elements that need to lose one electron to
become energetically stable: Na1+ + Cl1NaCl (table salt)
 The alkali metals (IA) are metals that
react with water to form alkaline (basic)
solutions; they commonly react with the
halogens

The Periodic Table
The alkaline earth metals (IIA) commonly
react with oxygen to form heat-resistant
oxides; the term earth is an historic one
that implies a heat-resistant oxide
 If you understand the periodic table you
can make predictions about what elements
should be able to form simple compounds;
you can also answer what seem to be
unrelated questions.

The Periodic Table


Questions such as:
Why is He and not H gas
used as a dirigible floatation
gas?

Why did radioactive Sr
particles in the fallout from
nuclear weapons testing lead
to a ban on above-ground
nuclear testing?

Why did one of the original
Star Trek episodes involve a
creature composed of Si?
The Periodic Table



Other points of interest:
Heavy elements (metals) - elements that are
“biologically heavy” ; our bodies can’t effectively
secrete them through the urine, feces, or
perspiration. Examples: As, Hg, Pb, Al. These
may accumulate in the body and produce toxic
response. They especially adversely affect the
Central Nervous System. How does this relate to
the Mad Hatter in “Alice in Wonderland”?
Since 2007, what possible source of lead (Pb)
contamination has many U.S. parents worried?
The Periodic Table

Note in the following slides
how residual lead poisoning
is still problematic in many
U.S. cities and that higher
bone-lead levels have also
been linked to an increase
incidence in teen criminal
delinquency
Lead Sources?
Soil, pre-1980s
paints, lead
municipal water
pipes (Detroit), old
lead smelters (Detroit)
Source: Geotimes, May 2005
Neighborhoods to get additional lead tests
March 10, 2004
BY WENDY WENDLAND-BOWYER AND TINA LAM
FREE PRESS STAFF WRITERS
The Michigan Department of Environmental Quality plans to conduct hundreds of tests
in two neighborhoods with dangerously high levels of lead in the soil to find out whether
it came from former lead smelters.
The two neighborhoods -- one in Hamtramck and the other in Detroit -- are downwind
from possible old lead smelters, according to the DEQ report released late Tuesday.
The state tested the soil on publicly-owned property in residential neighborhoods near
10 former smelting sites late last year. Almost all the sites had high levels of lead in the
soil. Three sites had high lead levels where the wind would have carried it if it had come
from the old smelters, the report said.
The other seven sites either showed high lead levels in no particular pattern or low lead
levels.
Heavy Metal Poisoning and
Criminal Behavior?
Source: Geotimes, May 2005
The Periodic Table


Note how this issue
remains in the
news.
Be forewarned:
cadmium, another
heavy metal, has
replaced lead in
many manufactured
products such as
some toys
detnews.com; 12/25/2009
The Periodic
Table

Mercury (Hg)
is another
heavy metal of
concern; note
that the source
of most of this
contamination
is coal-fired
electric power
plants
The Periodic Table
Pay attention to
this issue; it’s not
commonly
discussed in the
local or state
press.
The Periodic Table
Superconductivity - the transfer of
electricity with 100% efficiency. Since
1986 research advances have produced
superconductors which operate at about
-2200F; not widely applicable yet
 What would be some possible applications
of higher-temperature (say ~ 00 – 600F)
superconductors?

The Periodic Table

On a related note,
nearly 100% efficient
electrical transfer
using carbon
nanotubes, essentially
folded layers of
graphite, has been
achieved in the
laboratory! (see
figure)
Representation
of a carbon
nanotube
The Periodic Table


Application? Scientists and
engineers are salivating
over possibly being able to
connect multiple carbon
nanotubes to create
carbon-based molecular
electronic devices to
replace silicon-based
computer chips. This is just
one possible application.
Single layers of graphite
(graphene) may also have
numerous applications.
2/2014