Transcript 10.3 Artificial Transmutation

10.3 Artificial Transmutation
This painting of an alchemist’s
laboratory was made around
1570. For centuries, these
early scientists, known as
alchemists, tried to use
chemical reactions to make
gold. The alchemists failed in
their attempts to turn lead into
gold.
10.3 Artificial Transmutation
Nuclear Reactions in the Laboratory
How do artificial transmutations occur?
Transmutation is the conversion of atoms of
one element to atoms of another.
Scientists can perform artificial
transmutations by bombarding atomic nuclei
with high-energy particles such as protons,
neutrons, or alpha particles.
10.3 Artificial Transmutation
Nuclear Reactions in the Laboratory
Transmutation involves a nuclear change, not a
chemical change.
• Nuclear decay is an example of a transmutation that
occurs naturally.
• Transmutations can also be artificial.
10.3 Artificial Transmutation
Nuclear Reactions in the Laboratory
In 1919, Ernest Rutherford performed the first
artificial transmutation by exposing nitrogen gas
to alpha particles.
• Some of the alpha particles were absorbed by the
nitrogen nuclei.
• Each newly formed nucleus then ejected a proton,
leaving behind the isotope oxygen-17.
10.3 Artificial Transmutation
Transuranium Elements
How are transuranium elements produced?
Elements with atomic numbers greater than 92
(uranium) are called transuranium elements.
Scientists can synthesize a transuranium
element by the artificial transmutation of a
lighter element.
10.3 Artificial Transmutation
Nuclear Reactions in the Laboratory
All transuranium elements are radioactive, and
they are generally not found in nature.
Neptunium was the first transuranium element
synthesized. In 1940, scientists at the University
of California, Berkeley, bombarded uranium-238
with neutrons, producing uranium-239.
The uranium-239 underwent beta decay to form
neptunium-239.
10.3 Artificial Transmutation
Nuclear Reactions in the Laboratory
Most transuranium elements have only been
produced for research, but some are synthesized
for industrial use.
• Americium-241 is a transuranium element used in
smoke detectors.
• The decay of plutonium-238 is used to generate
electrical energy in some space probes.
10.3 Artificial Transmutation
Nuclear Reactions in the Laboratory
In 1977, NASA launched
Voyager 1 and Voyager
2 spacecraft to explore
the outer solar system.
They are powered by the
alpha decay of
plutonium-238.
10.3 Artificial Transmutation
Particle Accelerators
Some transmutations require particles that are
moving at extremely high speeds.
Particle accelerators cause charged particles to
move very close to the speed of light.
The fast-moving particles collide with atomic
nuclei.
Scientists have produced more than 3000
different isotopes.
10.3 Artificial Transmutation
Particle Accelerators
Scientists also conduct collision experiments in
order to study nuclear structure.
• More than 200 different subatomic particles have
been detected.
• A quark is a subatomic particle theorized to be
among the basic units of matter.
• According to the current model of the atom, protons
and neutrons are made up of quarks.
10.3 Artificial Transmutation
Particle Accelerators
This particle detector records
subatomic particles produced
in the Tevatron, the most
powerful particle accelerator in
the world.
The Tevatron is located at
Fermilab in Batavia, Illinois.
10.3 Artificial Transmutation
Assessment Questions
1. Which of the following is a type of atom
transmutation?
a.
b.
c.
d.
alpha decay
gamma decay
chemical reaction
ionization
10.3 Artificial Transmutation
Assessment Questions
1. Which of the following is a type of atom
transmutation?
a.
b.
c.
d.
alpha decay
gamma decay
chemical reaction
ionization
ANS: A
10.3 Artificial Transmutation
Assessment Questions
2. To study the structure of the atomic nucleus,
scientists use particle accelerators to
a. combine small nuclei into larger nuclei.
b. cause chemical reactions to occur rapidly.
c. cause collisions of particles moving near the speed of
light.
d. magnify nuclei so they can be studied on a computer
monitor.
10.3 Artificial Transmutation
Assessment Questions
2. To study the structure of the atomic nucleus,
scientists use particle accelerators to
a. combine small nuclei into larger nuclei.
b. cause chemical reactions to occur rapidly.
c. cause collisions of particles moving near the speed of
light.
d. magnify nuclei so they can be studied on a computer
monitor.
ANS:
C
10.3 Artificial Transmutation
Assessment Questions
1. Scientists make transuranium elements by the
artificial transmutation of lighter elements.
True
False
10.3 Artificial Transmutation
Assessment Questions
1. Scientists make transuranium elements by the
artificial transmutation of lighter elements.
True
False
ANS:
T