Nuclear Chemistry and Nuclear Equations
Key Terms:
1. Atomic Mass (A) is the sum of protons and neutrons in an atom. Electrons are
not counted because they have a relative mass of zero.
2. Atomic Number (Z) is the number of protons in an atom.
3. Ions are atoms that have either lost or gained electrons. In a neutral atom,
the number of electrons must be equal to the number of protons since the
charges must cancel each other. In an ion that has a negative charge,
electrons were added. In an ion that has a positive charge, electrons were
lost.
4. Isotopes are atoms of the same element that have different atomic masses.
Since they are atoms of the same element, they must have the same number
of protons. Therefore, they must have different numbers of neutrons.
5. Radiation is the penetrating rays given off by radioactive elements. There are
three main types of radiation: Alpha, beta, and gamma.
6. Radioactivity is the property by which elements give off radiation.
7. Radioisotopes are isotopes of elements that are unstable and decay by
undergoing radioactive decay.
8. Radioactive decay is the process where unstable elements become stable by
emitting radiation.
9. Radioactive
10. Rate law is a mathematical expression relating the concentration (or for
nuclear chemistry, the activity) of the reactants to the amount of time the
reaction takes.
11. Alpha: alpha particles consist of two protons and two neutrons. They do not
have any electrons; therefore, their charge is positive two (+2). They are
identical to the nucleus of a Helium atom. When an alpha particle is emitted
from a nucleus, the atomic number decreases by two, and the atomic mass
decreases by four.
12. Beta: Beta particles consist of an electron. They have no mass and a negative
one charge. When a beta particle is emitted from a nucleus, the mass does not
change, but the atomic number increases by one. The electron that comes
from the nucleus is ejected from a neutron, which is made up of a proton and
an electron as well as other subatomic particles which are unimportant to
this topic (this also explains why a neutron has a neutral charge – the
positive charge of the proton and the negative charge of the electron cancel
each other). A proton is left after the neutron decays, which is why the atomic
number increases by one.
13. Gamma: Gamma radiation is high energy, there is no mass and no charge.
Gamma radiation accompanies most, but not all, radioactive decay. There is
no change in mass or atomic number.
14. Positron: A positron is a positively charged electron or a positively charged
beta particle. During positron decay, the atomic mass remains the same, but
the atomic number decreases by one.
15. K-capture: K-capture, or electron capture, is where a nucleus of an atom
captures an electron of the atom. The electron is then combined with a
proton to create a new neutron. The atomic mass does not change, but the
atomic number decreases by one (with a corresponding decrease in the
number of electrons, so the atom remains neutral).
a. Note: Positron decay and K-capture result in the same product(s).
16. Neutron decay: The nucleus of an atom gives off a neutron The atomic mass
decreases by one, while the atomic number remains the same.
17. Neutron capture: The nucleus of an atom captures a neutron. The atomic
mass increases by one, while the atomic number remains the same.
18. Daughter products refers to the element or elements that are left after the
nuclear decay.
19. Magic numbers are the numbers of protons or neutrons that are generally
found to make the element stable. Numbers are: 2, 8, 20, 28, 50, 82, 126.