Nuclear Chemistry and Radioactivity Flashcards

Comprehensive vocabulary flashcards covering nuclear chemistry, atomic structure, isotopes, radioactive decay types, measurement units, and historical nuclear accidents.

Atomic Number (Z)

The number of protons in an atom's nucleus, which defines the specific element.

Compound

A substance formed when two or more elements chemically bond in fixed ratios by mass, with properties different from its constituent elements.

Mixture

A physical combination of substances with no chemical bonds between components, which can be separated by physical methods like filtration or distillation.

Nucleons

The collective term for protons and neutrons located within the nucleus.

Strong Nuclear Force

A short-range force that holds the nucleus together by overcoming the electrostatic repulsion between positively charged protons.

Mass Number (A)

The total number of protons plus the number of neutrons in an atom's nucleus; expressed as $A = Z + N$.

Isotopes

Atoms of the same element that have the same atomic number (Z) but different numbers of neutrons, resulting in different mass numbers (A).

Tritium ($^{3}_{1}H$)

A radioactive isotope of hydrogen with one proton and two neutrons, having a half-life ($t_{1/2}$) of $12.43$ years.

Alpha Radiation ($\alpha$)

A type of radiation consisting of 2 protons and 2 neutrons (a Helium nucleus) with high ionizing power but very low penetrating power.

Beta Radiation ($\beta^-$)

High-speed electrons emitted from a nucleus with moderate ionizing and penetrating power; can be stopped by plastic or aluminum.

Gamma Radiation ($\gamma$)

Weightless electromagnetic waves (photons) with the speed of light, possessing low ionizing power but very high penetrating power requiring lead or concrete shielding.

Half-life ($t_{1/2}$)

The time required for half of the radioactive atoms in a sample to undergo decay, calculated using the formula $t_{1/2} = \frac{\ln 2}{\lambda} = \frac{0.693}{\lambda}$.

Carbon-14 Dating

A technique developed by Willard Libby used to date organic materials up to $50,000–60,000$ years old based on the decay of $^{14}C$ after an organism's death.

Gray (Gy)

A unit of absorbed radiation dose defined as $1\,J/kg$ of material.

Sievert (Sv)

A unit measuring the biological effect of radiation, calculated as the absorbed dose in Grays multiplied by the Relative Biological Effectiveness ($Sv = Gy \times RBE$).

Becquerel (Bq)

A unit of radioactivity defined as one nuclear disintegration per second.

Relative Biological Effectiveness (RBE)

A factor used to determine the biological damage of different types of radiation; for example, alpha particles have an RBE of $20$.

Chernobyl (1986)

A Level 7 'Major Accident' in Ukraine caused by a flawed RBMK reactor design and human error, resulting in massive radioactive release.

Fukushima Daiichi (2011)

A Level 7 nuclear accident in Japan caused by a $9.0$ magnitude earthquake and tsunami that disabled cooling systems, leading to reactor meltdowns.

Ionizing Radiation

Radiation with enough energy to knock electrons out of atoms, potentially causing cell death, DNA mutations, or cancer.