1. A neutron is absorbed by a heavy nucleus (e.g., Uranium-235). 2. The nucleus becomes unstable. 3. The nucleus splits into two or more lighter nuclei, releasing energy and additional neutrons. 4. These neutrons can then induce further fission reactions (chain reaction).

1. An unstable nucleus exists. 2. The nucleus spontaneously emits particles (alpha, beta, gamma) and/or energy. 3. The nucleus transforms into a more stable configuration, potentially a different element or isotope.

1. Extremely high temperatures and pressures are present in the star's core. 2. Hydrogen nuclei (protons) overcome electrostatic repulsion. 3. Hydrogen nuclei fuse to form helium, releasing energy. 4. Further fusion reactions create heavier elements.

A neutron is absorbed by a heavy nucleus, causing it to split into lighter nuclei and release energy and more neutrons.

Energy is released as kinetic energy of reaction products (fragments, particles) and high-energy photons (gamma rays).

The strong force is the fundamental force that binds protons and neutrons together in the nucleus, overcoming electromagnetic repulsion between protons.

Mass-energy equivalence states that mass and energy are interchangeable, described by the equation $E=mc^2$, where a small change in mass can result in a large change in energy.

Nuclear fusion is the process where two light nuclei combine to form a heavier nucleus, releasing energy due to the mass defect.

Nuclear fission is the process where a heavy nucleus splits into two or more lighter nuclei, releasing a significant amount of energy.

Radioactive decay is the spontaneous transformation of an unstable nucleus into a more stable configuration, often accompanied by the emission of particles or energy.

Half-life ($t_{1/2}$) is the time required for half of the radioactive nuclei in a sample to decay.

The decay constant ($lambda$) represents the probability of a single nucleus decaying per unit time. It is related to half-life by the equation $\lambda = \frac{\ln 2}{t_{1/2}}$.