Nuclear Chemistry Basics

Vocabulary flashcards summarising essential terms, particle symbols, radiation types, and decay rules from the nuclear-chemistry lecture notes.

Atomic Number (Z)

The number of protons in an atom’s nucleus; uniquely identifies the element.

Mass Number (A)

The total number of protons and neutrons (nucleons) in the nucleus of an atom.

Nuclear Notation (A/Z X)

A symbolic way to write nuclides where X is the element symbol, Z is the atomic number, and A is the mass number.

Proton (¹₁p)

Positively charged sub-atomic particle found in the nucleus; symbolised as ¹₁p in nuclear equations.

Neutron (¹₀n)

Neutral nucleon in the atomic nucleus; written as ¹₀n or n in nuclear reactions.

Electron (⁰₋₁e)

Negatively charged particle outside the nucleus; appears as ⁰₋₁e in β⁻ decay equations.

Nucleon

A collective term for the two particles that occupy a nucleus: protons and neutrons.

Nuclide

A specific type of nucleus characterised by a definite number of protons and neutrons.

Isotope

Atoms of the same element (same Z) that contain different numbers of neutrons (different A).

Nuclear Reaction

natural change of an isotope of one element into an isotope of a different element

Radioactivity

The spontaneous disintegration of an unstable nucleus into a more stable one while emitting radiation.

Alpha Radiation (α)

Emission of a ⁴₂He nucleus; weakest penetration—stopped by paper or clothing.

Beta Minus Radiation (β⁻)

Emission of an electron (⁰₋₁e); medium penetration—passes skin but not deeply.

Gamma Radiation (γ)

High-energy photons released when a nucleus shifts between energy levels; highly penetrating and involves no nucleon loss.

Positron Emission (β⁺)

Beta-plus decay that releases a positron (⁰₊₁e); occurs when the nucleus has too few neutrons (low N/Z).

Conservation in Nuclear Equations

The sums of mass numbers (A) and atomic numbers (Z) must be equal on both sides of a nuclear reaction.

High N/Z Ratio Rule

If a nucleus has too many neutrons (high N/Z), it usually undergoes β⁻ (negatron) decay to lower that ratio.

Low N/Z Ratio Rule

If a nucleus has too few neutrons (low N/Z), it can correct by positron emission (β⁺) or electron capture.

Alpha Decay Threshold

Nuclei with atomic numbers greater than 83 are typically unstable and tend to undergo α decay.

Difference from Chemical Reactions

Nuclear reactions release far greater energy and are unaffected by temperature, pressure, or catalysts, unlike chemical reactions.