Physical Science: Nuclear Reactions and Quantum Model

Comprehensive vocabulary flashcards covering subatomic structure, nucleosynthesis, nuclear decay and transmutations, radiation types, and quantum mechanical principles.

Atoms

Structures composed of a central nucleus surrounded by orbiting electrons.

Nucleus

The central core of an atom that consists of positively charged protons and neutral neutrons.

Element

A fundamental substance whose specific identity is determined solely by its number of protons.

Atomic Mass

The combined total number of protons and neutrons within an atom.

Nucleosynthesis

The cosmic process responsible for the formation of atomic nuclei and the creation of elements, occurring via fusion or fission and radioactive decay.

The Big Bang

The primordial cosmic event that created the initial, lightest elements—primarily $\text{H}$, $\text{He}$, and traces of $\text{Li}$.

Stellar Formation

The process where gravity pulls $\text{H}$ and $\text{He}$ together to form stars, inside of which extreme temperature and pressure drive nuclear fusion to forge elements from $\text{Be}$ to $\text{Fe}$.

Iron ($\text{Fe}$)

The element that marks the thermodynamic limit for normal stellar fusion.

Stellar Explosion

Catastrophic cosmic events, such as supernovae and neutron star collisions, that provide the massive energy inputs required to forge elements heavier than $\text{Fe}$ (e.g., Gold, Platinum, and Uranium).

Nuclear Fusion

A nuclear reaction through which light nuclei combine to form a heavier nucleus, generating less nuclear waste.

Nuclear Fission

The splitting of a heavy nucleus into lighter nuclei; this reaction sustains nuclear power plants and weapons and yields less radioactive products.

Mass Number ($A$)

The sum of the number of protons and neutrons in a nuclide, expressed as $A = Z + N$.

Atomic Number ($Z$)

The number of protons or positive nuclear charge in a nuclide, defining the element's identity.

Neutron Number ($N$)

The total number of neutrons present in an atomic nucleus, calculated as $N = A - Z$.

Isotopes

Atoms of the same element having the same atomic number ($Z$) but different mass numbers ($A$), characterized by having equal proton counts but differing neutron counts.

Transmutation

The process of converting one chemical element into a completely different element through radioactive decay or particle bombardment.

Nuclear Decay Reaction

Also called radioactive decay; a process where an unstable parent nucleus emits radiation to form more stable daughter nuclei of lower mass and/or lower energy.

Nuclear Transmutation Reaction

A reaction where a nucleus collides with a subatomic particle or another nucleus to produce a product nucleus that is more massive than the original reactant nucleus.

Radioactivity

A natural, spontaneous process by which unstable atomic nuclei release excess energy in the form of particles or electromagnetic waves.

Ionising Radiation

High-energy particles or waves that possess sufficient energy to remove electrons from interacting matter.

Alpha Radiation

Radiation denoted by $^4_2\text{He}$ or $^4_2\alpha$, composed of 2 protons and 2 neutrons; it cannot penetrate paper or clothing.

Beta Radiation

Radiation denoted by $^0_{-1}e$ or $^0_{-1}\beta$ consisting of high-speed electrons; it can pass through paper and clothing but is stopped by $0.5\,\text{cm}$ of lead.

Gamma Radiation

Massless, chargeless electromagnetic radiation ($\gamma$) that travels at the speed of light, penetrates completely through the body, and requires thick lead or concrete shielding to stop.

Positron Emission

Also known as beta-plus decay; a process where a proton in the nucleus decays into a neutron and emits a positron ($^0_{+1}e$).

Electron Capture

A nuclear process whereby an inner atomic electron ($^0_{-1}e$) is drawn directly into the nucleus, combining with a proton to form a neutron.

Antimatter

Matter composed of antiparticles that have identical mass to ordinary matter particles, but carry opposite electrical charge and differing quantum numbers.

Huygens' Principle

The physical principle stating that every point on a wavefront acts as a source of secondary spherical wavelets.

Heisenberg Uncertainty Principle

A fundamental quantum principle stating that it is impossible to simultaneously measure both the precise velocity and position of a subatomic particle.

Quantum

The specific amount of energy required to transition an electron from one energy level to another.

Principal Quantum Number ($n$)

The quantum number that designates the main energy level, orbital size, and average distance of an electron from the nucleus.

Azimuthal Quantum Number ($\ell$)

The quantum number representing the shape of an orbital or wave function, taking integer values ranging from $0$ to $n - 1$.

Magnetic Quantum Number ($m_\ell$)

The quantum number indicating the spatial orientation of an orbital around the nucleus, with integer values ranging from $-\ell$ to $+\ell$.

Spin Quantum Number ($m_s$)

The quantum number indicating the intrinsic spin orientation of an electron, holding possible values of $+\frac{1}{2}$ (spin up) or $-\frac{1}{2}$ (spin down).

Pauli's Exclusion Principle

The quantum rule stating that when two electrons occupy the same orbital, they must have opposite spins.

Aufbau Principle

The electron configuration rule stating that electrons fill lower-energy atomic orbitals before occupying higher-energy ones.

Hund's Rule

The rule dictating that every orbital in a subshell is singly occupied with electrons of parallel spin (upwards first) before any orbital becomes doubly occupied.