Nuclear Decay Basics Quiz

Concept: stability of nuclei. Unstable nuclei transform to become more stable. They do this by emitting particles or energy so the nucleus moves toward a lower-energy, more stable arrangement.

Concept: radiation as a sign of instability. Emission is part of many decay processes. Radiation is released because the nucleus is rearranging itself to reach greater stability.

Concept: nuclear composition. Protons and neutrons form the nucleus. Electrons are outside the nucleus, so they are not part of the atomic nucleus itself.

Concept: radioactivity definition. Radioactivity refers to spontaneous nuclear changes. This means the nucleus changes on its own without needing to be triggered by heating, pressure, or chemistry.

Concept: types of nuclear radiation. Alpha particles are nuclear radiation. They come directly from the nucleus during radioactive decay, unlike sound or heat conduction.

Concept: spontaneity of decay. It occurs naturally for unstable isotopes. The timing of decay for a single nucleus is random, but large samples show predictable patterns.

Concept: alpha particle structure. Alpha is a helium-4 nucleus. That means it contains 2 protons and 2 neutrons, giving it a +2 charge.

Concept: beta-minus radiation. Beta-minus decay emits an electron. This happens when a neutron in the nucleus changes into a proton and an electron is released.

Concept: gamma as em radiation. Gamma rays are very high-frequency em waves. They are photons (like light), but with much higher energy.

Concept: penetrating power. Gamma rays penetrate the most. Because they have no charge and very high energy, they interact less often and can pass through materials more easily.

Concept: atomic number (Z). Atomic number Z = number of protons. Z identifies the element, because changing the number of protons changes what element it is.

Concept: effect of alpha decay on Z. It loses 2 protons. Losing protons reduces the atomic number, so the element changes to a different one.

Concept: effect of alpha decay on A. Alpha removes 2 protons + 2 neutrons. That is 4 nucleons total, so the mass number drops by 4.

Concept: neutron-to-proton conversion in β decay. A neutron turns into a proton + electron (β). Because a proton is created in the nucleus, Z increases by 1 while the mass number stays the same.

Concept: identifying nuclear radiation. Alpha, beta, gamma are nuclear radiation; infrared is not nuclear decay radiation. Infrared is electromagnetic radiation but it is not produced by changes inside the nucleus in the way gamma is.

Concept: terminology. Radioisotope = radioactive isotope. The term simply means an isotope with an unstable nucleus that undergoes radioactive decay.

Concept: shielding and penetration. Alpha is least penetrating. Because alpha particles are heavy and charged, they lose energy quickly and are stopped by paper or the outer layer of skin.

Concept: beta penetration and shielding. Beta is moderately penetrating; thin metal can stop it. Beta particles are lighter than alpha and can pass through paper, but a thin sheet of aluminum often blocks them.

Concept: photons and properties of gamma. They are photons. Photons have no rest mass and no charge, which is why gamma rays can be highly penetrating.

Concept: overall idea of nuclear decay. Emission and transformation increase stability. The nucleus releases particles or energy so it can move toward a more stable nuclear structure.