Download Isotopes and Radioactive Decay

NAME________________________________________________
PERIOD_______________
DATE__________________________
Isotopes and Radioactive Decay
CHAPTER 4 NOTES:
ISOTOPES
ISOTOPES: Atoms that contain the same number of ______________ but a different number of ______________.

Isotopes containing more neutrons have a _____________________________ mass.

Despite the difference in mass, isotopes of an atom will have the ____________ chemical ____________.

Generally in nature most elements are found as ______________________ of ______________________.
An example of this can be found with the Potassium (K) in a banana. 93.26% of the potassium __________
have 20 _________________, 6.73% of the potassium atoms have ________ neutrons, and 0.01% of the
potassium atoms have 21 ______________________.
ATOMIC MASS: The weighted _________________ mass of the _________________ of a certain _____________.

Atomic mass is expressed in units of ________________________________________, which is defined as
the one-twelfth the mass of a _____________________________ atom. 1 amu is nearly equal to the mass
of a single _____________________ or a single _________________________.
ISOTOPE/NUCLEAR NOTATION:
ISOTOPE/NUCLEAR NOTATION FOR THE 3 ISOTOPES OF HYDROGEN:
Given the data in the table, calculate the atomic mass of unknown Element X:
ISOTOPE ABUNDANCE FOR ELEMENT X
Isotope
Mass (amu)
Percent abundance
6X
6.015
7.59%
7X
7.016
92.41%
Ex #1): Write nuclear symbols for 3 isotopes of carbon (atomic number = 6) in which there are 6, 7, and 8 neutrons
respectively.
Ex #2): A radioactive isotope that is used for radiation treatment of cancer is the Cobalt – 60 atom. How many
protons are there? How many neutrons are there?
RADIOACTIVE DECAY
NUCLEAR REACTION: Reaction that can change an _______________________into a new ___________________.
It requires a change in an atom’s _______________________________.

Radiation is the ____________________ and ______________________ emitted by radioactive materials.

Radioactive ______________ emit radiation because their _______________ are ___________________.

Radioactive decay is a ____________________________ process in which unstable nuclei _____________
energy by emitting ___________________________. Radioactive decay will continue to occur until a
stable _________________ has formed, which is often a different _____________________ altogether.

The most important factor in determining an atom’s stability is its _________________ of _____________
to _____________________. Nuclei are unstable when there are either too many or too few of protons or
neutrons.

Types of Radiation:
o
ALPHA RADIATION: Radiation that is made up of ____________________________ particles. An
______________________ particle contains _____________ protons and ____________ neutrons
and has a ______________ charge. An alpha ________________ is equivalent to a ____________
nucleus. Alpha particles are represented by _____________________ or ___________________.

o
Example of alpha radiation (the following equation is an example of a nuclear equation):
BETA RADIATION: Radiation that is made up of _______________________ particles. A
_____________ particle contains an ___________________ with a ___________ charge. Beta
particles are _____________________________________. Beta particles are represented by the
symbols ________________________ or __________________________.

o
Example of beta radiation (the following equation is an example of a nuclear equation):
GAMMA RADIATION: Radiation that is made up of ________________________ rays. A gamma
ray is high-energy and contains no _____________ and is represented by the symbol __________.
Gamma rays usually accompany ___________________ and ___________________ radiation.
Gamma rays also account for ______________ of the __________________ lost during
_________________________ decays. Since gamma radiation is massless the ________________
of gamma rays cannot end in the ____________________ of a new _______________.

Example of gamma radiation (the following equation is an example of a nuclear equation):
Characteristics of Radiation:
Alpha
Beta
Gamma
Symbol
Mass (amu)
Charge
HOMEWORK PRACTICE PROBLEMS:
1. Which subatomic particle identifies an atom as that of a particular element?
2. An element contains 66 electrons. Which element is it?
3. An element contains 14 protons. Which element is it?
4. Boron (B) has two naturally occurring isotopes: boron-10 (abundance = 19.8%; mass = 10.013 amu) and
boron-11 (abundance = 80.2%; mass = 11.009 amu). Calculate the atomic mass of boron.
5. Copper has two isotopes: Cu-63 (abundance = 69.2%; mass = 62.930 amu) and Cu-65 (abundance = 30.8%;
mass = 64.928 amu). Calculate the atomic mass of copper.
6. Three magnesium isotopes have atomic masses and relative abundances of 23.985 amu (78.99%), 24.986
amu (10.00%), and 25.982 amu (11.01%). Calculate the atomic mass of magnesium.
7.
Nitrogen has two naturally occurring isotopes, N-14 and N-15. Nitrogen’s atomic mass is 14.007. Which
isotope is more abundant and WHY?
8. Boron-10 emits alpha particles. Write a balanced nuclear reaction for this radioactive decay.
9. Cesium-137 emits beta particles. Write a balanced nuclear reaction for this radioactive decay.
10. Iodine-121 emits alpha particles. Write a balanced nuclear reaction for this radioactive decay.