Nuclear Decay and Reactions

Front

Radioactive Decay Noun

---

[ray-dee-oh-ak-tiv dih-kay]

Back

Radioactive Decay

---

The spontaneous process by which an unstable atomic nucleus loses energy by emitting radiation to achieve a more stable state.

---

Example: This graph shows that after each 'half-life' period, the amount of a radioactive substance decreases by half (from 100% to 50% to 25%, and so on).

Front

Nuclear Reaction Noun

---

[noo-klee-er ree-ak-shun]

Back

Nuclear Reaction

---

A process that alters the energy, composition, or structure of an atomic nucleus, involving changes in its protons or neutrons.

---

Example: A neutron hits a large atomic nucleus, causing it to split into smaller parts (fission products) and release energy and more neutrons.

Front

Transmutation Noun

---

[trans-myoo-tay-shun]

Back

Transmutation

---

The conversion of an atom of one element into an atom of another element through a nuclear reaction like decay.

---

Example: A fast-moving alpha particle collides with and merges into an atomic nucleus, changing it into a new, different element.

Front

Alpha Particle Noun

---

[al-fuh par-ti-kuhl]

Back

Alpha Particle

---

A positively charged particle, consisting of two protons and two neutrons, that is emitted by a nucleus during alpha decay.

---

Example: This diagram shows an unstable parent nucleus releasing an alpha particle (two protons and two neutrons), transforming into a new, smaller daughter nucleus.

Front

Beta Particle Noun

---

[bay-tuh par-ti-kuhl]

Back

Beta Particle

---

A high-speed electron or positron that is emitted from an atomic nucleus during the process of radioactive beta decay.

---

Example: This diagram shows a neutron inside an atom's nucleus changing into a proton, a process which ejects a high-energy electron (the beta particle).

Front

Gamma Ray Noun

---

[gam-uh ray]

Back

Gamma Ray

---

A penetrating, high-energy photon of electromagnetic radiation emitted from a nucleus as it transitions to a lower energy state.

---

Example: Radioactive cobalt undergoes nuclear decay to emit focused beams of gamma rays, a form of high-energy radiation, to a specific target for medical treatment.

Front

Alpha Decay Noun

---

[al-fuh dih-kay]

Back

Alpha Decay

---

A radioactive process in which an atomic nucleus emits an alpha particle, transforming into a new, different daughter nucleus.

---

Example: An unstable atomic nucleus (Uranium-235) releases an alpha particle (two protons and two neutrons) to become a new, smaller nucleus (Thorium-231).

Front

Beta Decay Noun

---

[bay-tuh dih-kay]

Back

Beta Decay

---

A radioactive process where a nucleus emits a beta particle, changing a neutron into a proton or a proton into a neutron.

---

Example: In beta decay, a neutron inside an atom's nucleus changes into a proton, releasing a high-energy electron (beta particle) from the nucleus.

Front

Gamma Decay Noun

---

[gam-uh dih-kay]

Back

Gamma Decay

---

A nuclear process where an excited nucleus releases excess energy by emitting a gamma ray, without changing its elemental identity.

---

Example: An excited atomic nucleus (parent) becomes more stable (daughter) by releasing energy in the form of a high-energy photon, called a gamma ray.

Front

Positron Noun

---

[poz-i-tron]

Back

Positron

---

The antimatter counterpart of an electron, possessing a positive charge but the same mass, emitted during positron emission beta decay.

---

Example: This image shows a positron as the 'positive twin' of an electron, highlighting that it's an elementary particle with the same mass but an opposite, positive charge.