Download nuclear reaction - Washburn O`Connor

Friday, 05/06/16
1) Warm-up: If you start with 100g of a radioactive
substance, how much will be left after 3 half-lives?
2) Review HW & Nuclear Notes
3) Complete Modeling Energy Investigation
4) Complete: Nuclear Half-Life Investigation- Link on
Weekly Schedule
5) Nuclear reaction equation practice
6) HW QUIZ MONDAY
Learning Target (NEW)I CAN: describe the role of
neutrons in the nucleus and the importance
of the band of stability & describe three different types of
radiation: alpha, beta, and gamma.
14.4 Chemical vs. Nuclear Reactions
• The involvement of energy in
chemical reactions has to do
with the breaking and forming
of chemical bonds.
• A nuclear reaction involves
altering the number of protons
and/or neutrons in an atom.
14.4 Radioactivity
• Almost all elements have one
or more isotopes that are
stable.
• “Stable” means the nucleus
stays together.
• Carbon-14 is radioactive
because it has an unstable
nucleus.
14.4 Radioactive Decay
• This process of
radioactive decay
results in an unstable,
radioactive isotope like
carbon-14 becoming
the more stable isotope
nitrogen-14.
14.4 Radioactive Decay
•
There are three types of
radioactive decay:
1. alpha decay,
2. beta decay, and
3. gamma decay.
14.4 Two types of Nuclear Reactions
• There are two kinds of nuclear reactions:
fusion and fission.
– Nuclear fusion is the process of combining the
nuclei of lighter atoms to make heavier atoms.
14.4 Fusion
• Nuclear fusion occurs in the Sun and the
resulting energy released provides Earth with
heat and light.
14.4 Types of Nuclear Reactions
• Nuclear fission is the
process of splitting the
nucleus of an atom.
• A fission reaction can be
started when a neutron
bombards a nucleus.
14.4 Using nuclear reactions in
medicine and science
• A half-life is a certain length of time after
which half of the amount of radioactive
element has decayed.
• As a radioactive element decays, it emits
harmful radiation such as alpha and beta
particles and gamma rays.
14.4 Using nuclear
reactions
• Radioactive dating is a process
used to figure out the age of
objects by measuring the amount
of radioactive material in it and
by knowing the half-life of that
substance.
• Understanding radioactive decay
of uranium-238 has allowed
scientists to determine that the
age of Earth is 4.6 billion years
old.
14.4 Using nuclear reactions in
medicine and science
• Radioisotopes (also called radioactive isotopes)
are commonly used as tracers in medicine and
science.
• By adding a radioactive isotope into a system
(such as the human body or an underground
water supply), problems can be detected.
1. Why is so much energy
required and released in a
nuclear reaction?
2. Gold-185 decays to iridium181. Is this an example of alpha
or beta decay?
3. What has to happen, in terms
of radioactive decay, for carbon14 to decay to nitrogen-14?
4. How is gamma decay
different from alpha or beta
decay?
1. A great deal of energy is required for and
released in nuclear reactions because these
reactions involve separating the particles in the
nucleus of an atom. These particles are held
together by strong nuclear force, the strongest
force known to science
2. The decay of gold-185 to iridium-181 is an
example of alpha decay because the atomic
mass decreases by four and the atomic
number decreases by two (from 79 for gold to
77 for iridium).
3. Beta decay has to occur for carbon-14
(atomic number 6) to decay to nitrogen-14
(atomic number 7). In this case, a neutron is
split into a proton and an electron, so the
atomic number increases by one but the
atomic mass stays the same.
4. Gamma decay involves only the release of
energy from the nucleus whereas both alpha
and beta decay involve the release of particles.
5. In your own words, describe
the difference between fusion
and fission. Why do certain
elements undergo fusion or
fission?
6. Which type of nuclear
reaction is used in modern-day
nuclear reactors? Why is the
other type of nuclear reaction
NOT used in modern-day energy
production?
7. When an atom of beryllium-9
is bombarded by an alpha
particle, an atom of carbon-12 is
produced and a neutron is
emitted. What kind of nuclear
reaction has just occurred?
5. Fusion is a nuclear reaction that involves two
nuclei fusing together and producing/ releasing
energy and particles. Fission is a nuclear
reaction that involves radioactive decay. Both
fusion and fission result in one element
transforming into a different element.
Radioactive isotopes are the starting materials
for nuclear reactions. Radioactive isotopes are
unstable because their nuclei get too full of
protons or neutrons to hold together by strong
nuclear force.
6. Fission is used in modern day nuclear
reactors. Fusion is not used because too much
energy is required to initiate these types of
reactions.
7. The transformation of beryllium-9 to carbon12 is a fusion reaction because the alpha
particle (a helium nucleus) fused with the
beryllium nucleus.
8. What is the half-life of each of these radioactive isotopes?
a. A radioactive isotope decreased to one-half its original
amount in 18 months.
b. A radioactive isotope decreased to one-fourth its original
amount in 100 years.
9. For each scenario below, indicate whether a chemical
reaction or a nuclear reaction is occurring.
a. When two compounds are combined, heat is released.
b. A sample of galium-68 is reduced to one-half of its original
amount in 68.3 minutes.
c. Radium-226 decays to radon-222.
d. A spark of energy is used to begin combustion of methane.
e. Hydrogen nuclei fuse in the Sun to make helium atoms.
8. Answers:
a. The half-life is 18
months.
b. The half-life is 50
years. After 50 years the
isotope was at one-half,
then after another 50
years, the isotope was at
one-fourth.
9. Answers:
a. Chemical
b. Nuclear
c. Nuclear
d. Chemical
e. Nuclear