Student Exploration: Nuclear Decay
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
The chart below gives the locations, charges, and approximate masses of three
subatomic particles. The approximate mass of each particle is given in universal
mass units (u).
Approximate
Particle Location Charge
mass
Proton Nucleus 1+ 1u
Neutron Nucleus 0 1u
Electron Orbitals 1 –
0u
1. The mass number of an atom is equal to the sum of protons and neutrons in
the nucleus.
A helium atom has 2 protons and 2 neutrons. What is the mass number of this
atom? 4
2. The atomic number of an element is equal to the number of protons in each
atom of the element. All helium atoms have 2 protons. What is the atomic
number of helium? 2
Gizmo Warm-up
While most atoms are stable, some are
radioactive, which means that they have a
tendency to undergo spontaneous nuclear decay.
The decay of radioactive atoms generally results in
the emission of particles and/or energy.
Several types of nuclear decay can be explored
with the Nuclear Decay Gizmo™. On the Gizmo,
check that Alpha decay and Uranium are
selected.
1. Click Play ( ) and then click Pause ( ) when the alpha particle is clearly
visible. What is an alpha particle made of? Consists of two protons and two
neutrons bound together into a particle identical to helium
, 2. Click Play and observe. Besides the alpha particle, what else is emitted from the
nucleus during alpha decay? Gamma rays are also emitted. Gamma rays are
energetic electromagnetic waves; they are often emitted in nuclear decay.