Nuclear Chemistry
Band of Stability: the nucleus of an atom wants to be as stable as possible. There are three reasons for an atom to be
unstable. The common decay products are named after the first three letters of the Greek alphabet—
Unstable Nucleus
Parent Element
Too many protons and
neutrons
Decay Process
[Emits/Changes]
Daughter Element
alpha decay
EMITS 2α and 2
n⁰
DOWN 2 elements
LEFT on the periodic table
Too many neutrons
beta decay-β-
n⁰  p+ and β-
UP 1 element
RIGHT on the periodic table
During Alpha decay an atom spits out two protons and two neutrons from its nucleus. This little bundle is called an "alpha
particle." Alpha decay usually happens in larger, heavier atoms.The symbol looks like Helium because Helium-4 has the
same number of protons and neutrons as an alpha particle (no electrons, though). During Alpha decay an atom's proton
count drops by two, a NEW element is formed.
The Alpha decay Equation:
Parent Element on the LEFT  Helium nucleus + New Element [Daughter Element]
An alpha particle does not have the ability to penetrate through most substances; a piece of paper will stop most alpha
particles. This type radiation is very dangerous if inhaled or ingested, in general it will not escape the human body. Radon
is an alpha emitter and can be inhaled since it is a gas. Some of the radon gas atoms will stick to the inside of your lungs
due the tar from smoking. Non-smokers are less at risk since they are able to exhale the majority of the radon gas.
ALPHA DECAY MODEL
ALPHA PARTICLE
SYMBOL
ALPHA DECAY EQUATION
During Beta Decay, a neutron inside the nucleus of an atom breaks down, changing into a proton, emits an electron. This
goes off harmlessly into space. The atomic number goes UP by one and mass number remains unchanged. The symbol
is the Greek symbol β-. We have changed a neutron into a proton, and an electron has been emitted.
Parent Element on the LEFT  Beta Particle + New Element [Daughter Element]
The Beta decay Equation:
Beta radiation can be stopped by WOOD. Beta negative decay is more penetrating than alpha decay because the
particles are smaller, but less penetrating than gamma decay. Beta electrons can penetrate through about one (1) cm of
flesh before they are brought to a halt because of electrostatic forces.
BETA DECAY SYMBOL
BETA DECAY MODEL
BETA DECAY EQUATION
Gamma rays are electromagnetic radiation similar to light. Gamma decay does not change the mass or charge of the
atom from which it originates. Gamma is often emitted along with alpha or beta particle ejection. A gamma ray is a way for
the nucleus to lose energy and move into a more stable state. Gamma radiation can be stopped by LEAD. Gamma rays
are extremely penetrable and it requires several inches of lead to stop them. In gamma emission, neither the atomic
number or the mass number is changed. Gamma radiation is the most penetrating of all. These photons can pass through
the body and cause damage by ionizing all the molecules in their way.
GAMMA DECAY SYMBOL
BETA DECAY MODELS