Nuclear Chemistry
Up to this point all combination of chemical species in a chemical reaction involved only
a breaking of bonds within the molecules that were reaction to form new bonds and new
molecules. The identity of the atoms participating in the reaction remained the same - so
in balancing the reaction we always made sure that the number of atoms of each element
on both sides of the eqn. was the same and the charge was equal as well.
In a nuclear process the identity of an atom may change.
In chemical rxns., only the outer electrons of the atoms are disturbed. Remember the
electrons are the species involved in bonding . In nuclear reactions, nuclear changes
occurs. If the element is changing elemental identity, then the # of protons in the nucleus
must change. If the mass # changes, but the # of protons stays the same, the number of
neutrons must change.
Two types of nuclear reactions
1) radioactive decay - process in which a nucleus spontaneously disintegrates, giving off
radiation.
2) nuclear bombardment reactions - nuclear reaction in which a nucleus is bombarded or
struck by another nucleus or nuclear particle. Here fission or fusion may occur.
An example of nuclear reactions
1) A sample of Uranium-238 decays spontaneously over a period of billions of years.
After about 30 billion years it is nearly gone. Strontium -90 formed by nuclear reactions
that occur in nuclear weapons testing is essentially gone after several hundred years.
2) Example of a nuclear bombardment reaction is the fusion that goes on in the sun which
is essentially four protons and electrons combining to make He.
Nuclide symbols:
(# of protons + # of neutrons) mass #
Symbol
or Symbol - mass #
(# of protons) atomic #
Radiation - small particles or light emitted from sample
Common radiation particles
Neutron
n
1
0n
Proton
p
1
1p
or
1
Deuteron
d
2
1d
or
2
Alpha

4
2 or
4
Beta Particle 
0
Positron
e+
Gamma Rays 
0
0
-1

1
0
+
0
-1
0
1H
1H
2 He
e-
1e

_______ is a fast electron
Positron is a ___________ _____________ ___________.
emission is the release of a helium nucleus - no electrons
(what is the charge?)
Radioactive Decay
Radioactivity exhibits 1st order kinetics, but it is really a special case. Here the half life is
independent of Temperature and Pressure and all other conditions. No one has yet
figured out a way to speed up or slow down radioactive decay. It is a property of the
particular isotope only and it even doesn’t depend on what kind of other atoms surround
the particular nucleus, that is what type of molecule the nucleus is part of.
Note that in theory it would take an infinite amount of time for the sample to completely
decay, but after 10 half lives, less than 0.1% radioactivity remains.
Half life eqns. for 1st order kinetics still apply: t1/2 = 0.693/k
Radioactive dating is based on
1) The fact that radioactive Carbon-14 is present in the atmosphere and decays by the
14
14
0
beta decay. The process is:
This has a half-life of 5730 yr.
6C ->
7N + -1 e
2) To use this for dating fact that living plants use atmospheric carbon dioxide and
maintain a constant C-14 level, but when they die, there is no more exchange so the
concentration of the C-14 isotope, and the  decay radiation decreases according to 1st
order kinetics.
Example
A piece of charcoal from the time of the formation of Crater Lake gave 7.0 disintigration
of carbon-14 nuclei per minute per gram of C. Present day living plant matter gives 15.3
disintegrations per minute per gram of total carbon. Determine the age of Crater Lake.
Why is carbon-14 dating limited to less than 50,000 years
How and why does a nucleus emit?
More than ____ naturally occurring isotopes (?).
______ are stable, and the rest are not!
_________ artificially made isotopes that are radioactive.
TO BE STABLE
Lighter elements -
Heavier elements require more _______ to stabilize the nucleus?
Magic # 2, 8, 20, 28, 50, 82 and
Neutrons Protons # of stable isotopes
Even Even
Even Odd
Odd Odd
No stable nuclides with atomic number greater than ___
Technetium and Promethium z = 43 and 61
If neutron to proton ratio is such that the nucleus is not stable, the nucleus emits radiation
(Overhead)
If the nucleus has excess neutrons, it can stabilize by:
converting proton to electron!
Beta Emission!
In Beta emission, the Beta particles are emitted from the nucleus, and the proton stays in
it.
Conversion of a neutron to a proton and emitted electron changes the identity of the
atom! Why?
"Alchemy"........................... Making gold out of other substances.
Consider Unstable Phosphorous-32 nucleus.
When this unstable molecule is converted to sulfur-32, its stability is achieved
Emission of Beta particle - b decay - results in nucleus with same mass # but different
atomic # which has increased by 1.
Balancing nuclear Eqns!
1) Sum of "mass #s" on both sides of eqn. must be the same!
2) Sum of "Atomic #" on both sides of the eqn. must be the same.
3) Remember the "mass # and atomic #. For:
 particle
 particle
positron
 emission
Example: Iodine-139 is a beta emitter. What product results when it emits!
Another Example:
What nucleus could undergo  decay to the only stable nucleus of gold?
Alpha emission can occur as well!
What product is formed in the alpha decay of Uranium-238?
What is the transmutation product of Polonium-210 under alpha emission?
What would happen in electron capture reaction?
Or positron emission?
Note this increases the neutron/proton ratio.

r electron capture
Capture and electron from an inner orbital
K + 0 -1 e -> 4 0 18 Ar (Usually emits X-ray or  ray too, since the outer electron
fills the void left by the inner electron
40
19

 decay decreases the neutron/proton ratio!
Fusion and Fission
Nuclear Binding Energy
Puzzling fact that the mass of an atom is always less than the sum of the masses of its
constituent particles.
For instance the mass of a helium-4 atom is 4.00260 amu
Mass of 2 electrons = 2 x 0.000549 amu
Mass of neutron is 1.675x10- 2 4 g so 2 x 1.00867 amu
Mass of proton is 1.673x10- 2 4 g so 2 x 1.00728 amu
Sum of mass
= 0.00110 amu
= 2.01734 amu
= 2.01456 amu
= 4.03300 amu
So there is a difference of m = -0.03040 amu. This mass difference is explained by the
fact that when the nucleons come close together they bind so energy must be lowered.
This is related to the binding energy.
The binding energy is the energy required to break a nucleus into its individual protons
and neutrons.
Example
The 1 9 9 F isotopes has an atomic mass of 18.9984 amu
Nucleus has 9 protons and 10 neutrons, 19 nucleons
proton mass - 1.007825 amu
neutron mass - 1.008655 amu
9 x 1.007825 + 10 x 1.008655 amu = 19.15708 amu
This is larger than the measured mass of 1 9 9 F
This is a difference between the mass of the atom and sum of the masses of the nucleons
is called the mass defect.
Convert mass defect into energy according to Einstein, E = mc2
m = 18.9984 - 19.15708 = -0.1587
E = -0.1587amu x (3.00x108 m/s)2 = -1.43 x 101 6 amu m2 /s2
1 amu = 1.066 x 10- 2 7 kg
1 J = 1 kg m2 /s2

E = -1.43 x 101 6 amu m2 /s2 x 1.066 x 10- 2 7 kg / amu = -2.37 x 10- 1 1 J
This is the energy released when on Fluorine-19 nucleus is formed from 9 protons and 10
neutrons.
Looking at a figure of the nuclear binding energy with respect to atomic mass
indicates that a mass # of around 56 is the most stable. Isotopes with mass numbers
less than 56 could combine to form a more stable nucleus and when the mass is
greater than 56 the nucleus should fall apart to become more stable.
Fusion
98% of all matter in the Universe is made of hydrogen and helium
At its conception only the lightest element, hydrogen was around but later as the
universe expanded, stars were born when the hydrogen clouds collapsed under
gravitational forces
Figure
Hydrogen fused together in the star and formed helium. This liberates a massive amount
of energy as photons.
4 1 1p ->
4
2He
+ 0 0
Where does this massive energy come from?
Process is called fusion - it is how the sun makes energy
Transuranium Elements - Elements with atomic numbers greater than 92
The elements are typically prepared by bombarding heavy nuclei with light ones
252
98Cf
+
10
5
B -> 2 5 7 103Lr + 51 0n
the new element element - 268 was prepared by bombarding Bismuth wih Cobalt.
209
83
Bi +
59
27
Co ->
268
110
Und
+
1
0n
Und is Unnildecinnium
Thes transuranium elements are unstable, and most have very short half lives for instance 2 5 7 103 Lr is 0.65 s,
In 1930 some people, Lisa Meitner, Otto Hahn and Frita Strassmen and Fermi were
trying to produce new transuranium elements by bombarding Uranium with neutrons.
Hahn and Co. found:
235
92
U + 1 0 n ->
139
56 Ba
+
94
36
Kr + 3 1 0 n + 0 0
In this fission reaction the 2 3 5 U is broken down to smaller particles and energy called
atomic energy.
Note that each fission of Uranium-235 produces 3 neutrons which in turn generate more
fission by colliding with other Uranium-23
See figure:
If even one of these produces new fission, then the process is self propagating. If all
there neutrons are allowed to produce new fission, then the rate of reaction increases
constantly and eventually one gets a nuclear explosion.
Rate of fission can be controlled by putting boron control rods in the reactor to absorb
neutrons!
The energy released can be used to heat water to make steam and drive turbines to get
electricity - nuclear power plants
Waste - Fission products are highly radioactive themselves, with long half lives.
Need to be stored for a long time. No way to speed up or slow down radioactive decay.
Nuclear binding energy - energy required to break up a nucleus into its component
neutrons and protons
Organic Chemistry
Chemistry of compounds containing carbon:
Several million have been described so far and thousands of new ones discovered every
year. What is it about carbon that makes it so unusual?
Atomic electronic configuration:
1s2 2s2 2p2 - Know it can make compounds like methane (CH4) and CCl4 - what shape?
Lewis Structures, VSEPR
Tetrahedral - Four Equivalent bonds - so think of it in terms of valence bond theory
1) orbital on one atom comes to occupy a portion of the same region of space as an
orbital on the neighboring atoms are said to overlap
2) The total number of electrons in both orbitals is no more than two.
Hybrid orbitals - used to describe bonding that is obtained by taking combinations of
atomic orbitals of a particular atom so the bonds it makes are all similar.
Remember orbital diagrams in CH4
or in H2CO
or in H2C2
Classification of Organic Compounds is described by the diagram in this figure:
A series of compounds in which one compound differs from the preceding one by a -CH2
Group is called a homologous series. The alkanes constitute a homologous series.
Members of a homologous series have similar chemical properties and often physical
properties change in a regular way.
B.P. and M.P. increasing molecular weight
Straight chain alkanes have a single bond connecting the carbon atom backbone
surrounded by hydrogen atoms. They are of formula CnH2n+2
straight chain, or normal alkanes have all carbon atoms bonded to one another to give a
single chain with hydrogen filling out the four valences of each carbon atom
In addition to straight-chain alkanes, branched-chain alkanes are also possible.
isobutane
has the same molecular formula (formula unit) as n-butane, C4H10, but a different
structural formula
Butane and isobutane are said to be structural or constitutional isomers.
Nomenclature of Alkanes
Nomenclature developed over several years as a way of understanding and classifying
their structures. Nomenclature it now formulated in rules agreed upon by the IUPAC.
The first four have long established names,
methane, CH4
ethane, C2H5
propane, C3H8
butane, C4H10
Higher members of the series are named from the Greek words indicating the number of
carbon atoms in the molecule with the suffix “ane” added.
C5H12 - straight chain called pentane
C6H14 - hexane
C7H16 - heptane
C8H18 - octane
C9H20 - nonane
C10H22 - decane
For branched chain alkanes:
1) Determine the longest continuous (not necessarily straight chain of carbon atoms in the
molecule. the base name of the branched-chain alkane is that if the normal alkane
corresponding to the longest chain.
2) Any chin branching off the longest chain is named as an alkyl group. An alkyl group
is an alkane less one hydrogen atom. When a hydrogen atom is removed from an end
carbon atom of a straight alkane, the resulting alkyl group is named by changing “ane” to
“yl”.
Example:
H-CH3, methane
-CH3, methyl
3) To completely name the branch off the main chain, we must use a number that locates
that branch on the longest chain. For this purpose, you number each carbon atom on the
longest chain in whichever direction gives the smaller number for the locations of all
branches.
Branch name and base name are written as a single word with a hyphen following the
number
4) When there are more than one alkyl branch of the same kind, say two methyl groups,
then this number is indicated by a Greek prefix, such as di-, tri-, or tetra- used with the
name of the alkyl group. The position of each group on the longest chain is given by
numbers. Note the position numbers are separated by commas and followed by a hyphen.
When there are two or more different alkyl branches, the name of each branch, with its
position number, precedes the base name. the branch names are placed in alphabetical
order.
Examples
2,3 dimethylbutane
3-ethyl-2-methylhexane
2,2-dimethylhexane
Write condensed structural formula of 4-ethyl-3-methylheptane
3,3 dimethyloctane
Cycloalkanes - don’t follow CnH2n+2 rule since connected in a ring fashion.
Alkenes and Alkynes
Alkenes - CnH2n with just one double bond
Alkynes - CnH2n-2 with just one triple bond
Unsaturated hydrocarbons - Similar naming rules for them, except longest chain with
double or triple bond
H2C=CH2
ethene - ethylene lingering old nomenclature called common name
HC≡CH
ethyne - acetylene
Numbering occurs from the end nearest the multiple bond number - 1st carbon in double
bond
1
2
3
4
5
CH2 = CH - CH2 - CH - CH3
CH3
4-methyl-1-pentene
Example
Write the condensed structure for 2,5-dimethyl-2-heptene
Alkenes give rise to another type of isomerization called Geometric Isomers. These are
isomers where the atoms are joined to one another but because there is no free rotation
about the double bond. Called cis and trans isomers
cis-2-butene
trans-2-butene
Different boiling points indicate different compounds
The simplest organic compounds are the hydrocarbons compounds containing only
carbon and hydrogen! All other organic compounds are considered, for classification
purposes to be derived from the hydrocarbons.
SubClassified into two main groups!
1. Aromatic Hydrocarbons
- hydrocarbons containing benzene rings or similar strucures
2. Aliphatic Hydocarbons - all hydrocarbons that do not contain benzene rings
CH4 molecular formula
structural formula
Sub Sub classifications include:
H
H - C -H
H
a) saturated hydrocarbons - a hydrocarbon where all carbon atoms are bonded to max #
of hydrogen (no multiple bonds)
b) unsaturated hydrocarbons - hydrocarbons with carbon-carbon double or triple bonds
Alkanes, also called paraffins - are saturated hydrocarbons with general formula CnH2n+2.
For n=1 you get the formula CH4, n=2 you get C2H6 etc.
Derivatives of Hydrocarbons
Certain groups of atoms in organic molecules are particularly reactive and have
characteristic properties.
These are the functional groups, a reactive part of the molecule that reacts readily and
predictably.
C=C bond is a functional group for example. Many functional groups include atoms with
lone pairs. C=O is a functional group.
Looked at hydrocarbons and their reactions, and all other organic compounds are
considered to be derivatives of hydrocarbons where one or more hydrogen atoms of a
hydrocarbon have been replaced by noncarbon atoms to give a functional group.
Structure of General Compound
Name of functional Group
Organic Halide
Alcohol
Ether
Aldehyde
Ketone
Carboxylic Acid
Ester
Amine
Amide
Alcohols and Ethers
Alcohols and Ethers are named by IUPAC rules similarly to those for hydrocarbons,
except the stem name is determined from the longest chain containing the carbon atom to
which the OH is attached. the suffix for the stem name is “ol”. the position of the OH
group is indicated by a number preceding the stem name.
alcohols are classified by the number of ca atoms attached to the carbon atom to which
the -OH group is attached.
1- butanol
2-butanol
2-methyl-2-propanol
Common names for ethers are formed from the hydrocarbon groups plus the word ether.
CH3OCH2CH2CH3
methyl propyl ether
Or by IUPAC rules, the ethers are named as “oxy” derivatives based on the longest
hydrocarbon chain.
1-methoxypropane
Aldehydes and Ketones
Aldehydes and ketones are compounds containing a carbonyl group. C=O
An aldehyde is a compound containing a carbonyl group with at least on H attached.
common names: fomaldehyde, acetaldehyde
A ketone is a compound containing a carbonyl group with two hydrocarbon groups
attached to it.
common names: acetone, methyl ethyl ketone based on naming the two groups on either
side of the carbonyl group
IUPAC rules for naming aldehydes and ketones are similar to the rules of naming for
alcohols. Find the longest carbon chain containing the carbonyl group to get the stem
hydrocarbon name. Then change the “e” at the end of the hydrocarbon name to al for
aldehydes or one for ketones. In the case of the aldehydes, the carbon atom of the -CHO
group is always the number 1 carbon. In ketones the carbonyl group may occur in
various positions in the chain, and the position of the carbonyl group is given by a
number be for the stem name, like the position of the hydroxyl group in alcohols.
2 butanone
methanal
ethanal
Carboxylic Acid
Contain the carboxyl group -COOH
The carbonyl group attached to the OH makes the proton weakly acidic.
Common names here as well since these types of compounds have been known for a long
time.
IUPAC rules name these carboxylic acids like for aldehydes except that “oic” is added
with the word acid on the stem name of the longest carbon chain containing the carbonyl
of the carboxyl group.
acetic acid
ethanoic acid
Ester
Made from carboxylic acid and alcohol have carbonyl group with oxygen, similar to
carboxylic acid, but with hydrocarbon on the end instead of a proton.
Nitrogen Containing
Amines
Organic bases that are derived by replacing one or more hydrogen atoms of ammonia
withy hydrocarbon groups.
Primary Amines
Secondary
Tertiary
Amides are nitrogen-containing hydrocarbons derived from the reactio of ammonia, or of
a primary or secondary amine, with a carboxylic acid.
ammonia
+
acetic acid
-> acetamide
Nylon is an example of a polyamide.
+ water