Periodic Table
Unit 4 Nuclear Chemistry
Marie Curie named the process by which materials give off rays of energy
________________. A radioactive atom, or radioisotope, undergoes drastic changes as it
emits this energy, called _________________; due to the instability of their nuclei. The
stability of the nucleus depends on the relative proportion of neutrons to protons as well
as the overall size of the nucleus. _______________________ is the process by which
an unstable nucleus emits radiation in order to lose energy. This process is spontaneous,
not requiring the input of energy and eventually results in a stable isotope of a different
element from the original radioisotope.
Three types of radiation can be emitted during radioactive decay:
1) ___________________, which consists of helium nuclei, also known as
________________________ and contain two protons and two neutrons and
carry a double positive charge
2) ____________________, which consists of fast moving electrons formed by
decomposing a neutron in the atom. The neutron decomposes into a ________,
which remains in the nucleus and a ____________________, the electron, which
is released. This particle carries a negative charge (indicated by the subscript –1
and a superscript 0 indicating a virtual lack of mass) 0-1 e
3) _____________________, which is high energy electromagnetic radiation, often
emitted along with alpha or beta radiation by the nuclei of disintegrating
radioactive isotopes. Since gamma rays have no mass or charge, their emission
does not alter the atomic number or mass number of the atom.
All nuclei with atomic number greater than _____ are radioactive and thus undergo
decay. Most of them emit alpha particles, decreasing the mass number by ____ and the
atomic number by _____. In this emission, a small amount of energy associated with
radiation is produced while a small quantity of mass is lost.
Every radioisotope has a characteristic rate of decay measured by the time required for
one-half of the nuclei of a sample to decay to stable products. This rate is known as the
_______________ and can be calculated using the formula A = A0 X (1/2)t/T
When the nuclei of some isotopes are bombarded with neutrons, they undergo ________,
the splitting of a nucleus into smaller fragments. This process can unleash large amounts
of energy and with the release of additional neutrons as the nucleus fractures, can start a
chain reaction. In a controlled chain reaction, the energy can be harnessed and used to
produce electricity, like in a nuclear ___________. Uncontrolled nuclear chain reactions
are started by devices like _________________________. Another type of nuclear
reaction results when nuclei combine to produce a new nucleus of greater mass. This
reaction also requires two beta particles and is known as nuclear _____________. This is
the type of reaction that occurs in the sun. In solar fusion, hydrogen nuclei fuse to make
helium nuclei. The drawback to using fusion as an affordable source of energy
production is that it only takes place at extremely high _______________________.
H. Cannon, C. Clapper and T. Guillot
Klein High School
Nuclear Chemistry
1. A radioisotope of the element lead (Pb) decays to an isotope of the element
bismuth (Bi) by emission of a beta particle. Complete the equation for the decay
process by supplying the missing atomic number and mass number.
210
PB Æ 83Bi + 0-1e
2. Write the symbol and charge for each:
alpha particle
beta particle
gamma ray
3. The disintegration of radium-226 produces an isotope of radon and alpha
radiation. The atomic number of radium (Ra) is 88 and the atomic number of
radon(Rn) is 86. Write a balanced equation for this transformation.
4. The following radioisotopes are beta emitters. Write balanced nuclear equations
for their decay processes.
a. Carbon – 14
b. Strontium – 90
c. Potassium - 40
5. The following radioactive nuclei decay by emitting alpha particles. Write the
product of the decay process for each.
a. 23894 Pu
b.
210
c.
210
83
Bi
84
Po
6. A patient is administered 20 mg of iodine – 131. How much of this isotope will
remain in the body after 40 days if the half-life for iodine – 131 is 8 days?
7. How are the mass number and atomic number of a nucleus affected by the loss of
the following?
a. Beta particle
b. Alpha particle
c. Gamma ray
4-2
HC/CC/TG KHS
Nuclear Chemistry
For the following, fill in the missing information and tell the type of decay
8.
263
9.
14
Sg Æ 259Rf +
___________
C Æ 14N +
10.
+
___________
Æ134Xe + 100Sr +
___________
11. 2H + 3H Æ 4He +
___________
13. 63Zn Æ ______ + 0e
30
14. 237Np Æ
93
-1
4
He + _______
2
_________
__________
15. If you begin with 1000 atoms of C-14 with a half-life of 5730 years,
_______________ atoms will remain after one half-life.
16. If you begin with 1000 atoms of C-14, after 11460 years, which is
_______________half lives; _____________ C-14 atoms will remain, after three
half lives, __________ C-14 atoms would be left.
17. Thorium 234 has a half life of 25 days. In 25 days, _____% of the sample will
remain. In 50 days, __________ % of the sample will remain. In 150 days,
_______% of the sample will remain. (start with 100%)
18. Manganese-56 is a beta emitter with a half life of 2.6 hours. What is the mass of
Manganese-56 in a 2.0 mg sample of the isotope after 10.4 hours? What is the
mass and name of the remaining isotope (the other element)?
Look at the graph to the right:
19. What is the half-life for Sodium -24?
20. How much Sodium is left after 3 half lives?
21. 2 grams of Sodium remain after 30 hours, how many
grams did the original sample contain?
4-3
HC/CC/TG KHS