Regents Physics Review: Modern Physics and the Nucleus

Vocabulary flashcards covering the key terms of Modern Physics including wave-particle duality, atomic models, nuclear forces, and subatomic particle classification.

Wave-particle duality

The principle that electromagnetic waves, energy, and matter possess properties of both waves and particles.

Photoelectric effect

A phenomenon where light having a frequency above a certain minimum value causes electrons to be emitted from certain metals, demonstrating that light is quantized.

Quantum theory

The assumption that electromagnetic energy is emitted from and absorbed by matter in discrete amounts, packets, or quanta.

Photon

A quantum of electromagnetic energy which possesses both energy and momentum but has zero mass.

Energy of a photon equation

$E=hf$ or $E=\frac{hc}{\lambda}$, where $h$ is Planck's constant, $f$ is frequency, and $E$ is in joules.

Electron diffraction

The phenomenon that best supports the theory that matter has a wave nature.

Photon-electron collisions

Interactions that demonstrate light has particle properties; during these collisions, both energy and momentum are conserved.

Ground state

The lowest energy state of an electron within an atom.

Excited states

All energy states of an electron in an atom other than the ground state.

Absorption spectrum

Also called a dark line spectrum, it represents the specific amounts of energy an electron absorbs to jump to higher permitted energy levels.

Bright line spectrum

Also called an emission spectrum, it represents the specific amounts of energy emitted as an electron jumps down to lower permitted energy levels.

Ionization level

The level indicated by $n=\infty$; if absorbed energy is sufficient to reach this point and beyond, all amounts of energy are allowed.

Nucleons

The particles that make up the nucleus, specifically protons and neutrons.

Strong or nuclear force

The strongest known force that keeps nucleons together; it operates only at a very short range and is about $100$ times larger than the electrostatic force between protons.

Atomic mass unit (u)

A unit of mass very slightly smaller than the mass of a proton or neutron; its energy equivalent is $931\,MeV$.

Thermonuclear fusion

The nuclear process taking place in the sun where two light elements fuse together to form a heavier particle, converting mass into energy.

Nuclear fission

The nuclear process used in power plants and atomic bombs where a heavy element splits into smaller particles, converting mass into energy.

Fundamental forces (Strongest to Weakest)

The four forces of nature: (1) Nuclear or strong force, (2) electromagnetic force, (3) weak force, and (4) gravitational force.

Hadrons

The heaviest subatomic particles that interact through all four fundamental forces; they are subdivided into baryons and mesons.

Leptons

Less heavy particles that interact through only three fundamental forces (excluding the strong force), such as electrons, positrons, neutrinos, muons, and taus.

Positron

The anti-electron; it has properties similar to an electron except that it is positively charged.

Neutrino

A particle with minimal mass that possesses energy and momentum.

Antiparticle

A particle with the same characteristics as its corresponding particle but with opposite charge and opposite magnetic moment, denoted by a bar over its symbol.

Antimatter

Matter composed of antiprotons, antineutrons, and positrons; it possesses positive mass.

Baryons

The heaviest hadrons, each consisting of $3$ quarks.

Mesons

Hadrons of intermediate mass, each consisting of a quark and an antiquark.

Quarks

Fundamental particles with charges of $\pm \frac{1}{3}e$ or $\pm \frac{2}{3}e$; types include up, down, charm, strange, top, and bottom.

Proton quark content

A baryon composed of two up quarks and one down quark ($uud$).

Neutron quark content

A baryon composed of two down quarks and one up quark ($ddu$).