Radioactive Decay Flashcards

Flashcards for reviewing key vocabulary related to atomic structure and radioactive decay.

Proton

A subatomic particle with a relative mass of 1 and a relative charge of +1.

Neutron

A subatomic particle with a relative mass of 1 and a relative charge of 0.

Electron

A subatomic particle with a relative mass of 1/1840 and a relative charge of -1.

Atomic Number

The number of protons in an atom.

Mass Number

The sum of protons and neutrons in an atom's nucleus.

Isotopes

Atoms of the same element with different numbers of neutrons.

Radioactive Isotopes

Unstable isotopes that spontaneously disintegrate and emit particles or radiation.

Alpha (α) Particles

Positively charged helium nuclei emitted during radioactive decay; stopped by a piece of paper and strongly ionizing.

Beta (β) Particles

Negatively charged electrons emitted during radioactive decay; stopped by 0.5 cm of aluminum.

Gamma (γ) Radiation

Very high-energy electromagnetic radiation emitted during radioactive decay; requires >2cm of lead to stop it and weakly ionizing.

Radioactive Decay

The spontaneous disintegration of unstable nuclei with the emission of particles or radiation.

Half-Life

The time taken for the radioactivity of a radioisotope to fall to half of its initial value, or the time taken for half the atoms in a radioactive isotope to decay.

Positron Emission (β+ decay)

The process where a proton in the nucleus changes into a neutron and a positively charged positron is emitted.

Electron Capture (inverse β decay)

The process where an electron from the closest energy level falls into the nucleus, causing a proton to change into a neutron, emitting an electron neutrino.

Gamma Emission (γ)

High energy released from the nucleus, causing its energy to decrease, without forming new products.

Alpha Decay (α)

A helium nucleus is produced, the atomic number decreases by two, and the mass number decreases by four.

Beta Decay (β)

A neutron in the nucleus changes into a proton, and a negatively charged electron is emitted. The atomic number increases by one.