Chapter 3: Structure of Matter & Chapter 4: Electromagnetic Radiation Vocabulary

Comprehensive vocabulary flashcards covering atomic structure, historical models, bonding, radiation, and electromagnetic properties from Chapters 3 and 4.

Greek Atom

An early atomic concept based on the belief that four basic substances of matter (earth, water, air, and fire) could be modified by four basic essences (wet, dry, hot, and cold).

Dalton Atom

An atomic model proposed by John Dalton stating that elements are composed of identical atoms that look, react, and contrast alike, laying the foundation for the first periodic table of elements.

Thomson Atom

An atomic model formulated by Joseph John "J.J." Thomson, which concluded that electrons are a crucial component of all atoms and that negative and positive charges are equal, keeping the atom electrically neutral.

Rutherford Nuclear Model

An atomic model introduced by Rutherford describing the atom as containing a small, dense, positively charged center (nucleus) surrounded by a negative cloud of electrons.

Bohr Atom

An atomic model consisting of a small, dense, positively charged nucleus surrounded by negatively charged electrons revolving in fixed, well-defined orbits around the nucleus.

Fundamental Particles

The basic subatomic constituent parts of an atom, consisting of electrons, protons, and neutrons.

Nucleons

Particles centrally located within the nucleus of an atom, specifically referring to protons and neutrons.

Electron Shells

Three-dimensional pathways orbiting the nucleus where electrons reside; each shell represents a distinct energy level and has a maximum capacity defined by $2n^2$, where $n$ is the shell number.

Strong Nuclear Force

The powerful force that holds the particles within the nucleus of an atom together.

Centripetal Force

The force operating in an atom that keeps orbiting electrons from flying out of their orbits away from the nucleus.

Centrifugal Force

The force operating in an atom that prevents orbiting electrons from being pulled closer to or collapsing into the nucleus.

Electron-Binding Energy

The strength of attachment between orbital electrons and the nucleus of an atom.

Atomic Number

The total number of protons contained in the nucleus of an atom.

Atomic Mass

The total number of protons plus neutrons contained in the nucleus of an atom.

Isotopes

Atoms that possess the same atomic number (same number of protons) but have varying numbers of neutrons, resulting in different atomic mass numbers.

Isobars

Atoms that contain different numbers of protons and neutrons (different atomic numbers), but have the exact same atomic mass.

Isotones

Atoms that have the exact same number of neutrons in their nucleus but different numbers of protons.

Isomers

Atoms that have identical atomic numbers and identical atomic mass numbers, but exist in different energy states due to variations in nucleon arrangement.

Molecule

A structure formed when atoms of various elements combine; it represents the smallest particle of an element or compound that retains its chemical identity.

Chemical Compound

A substance formed when several molecules of the exact same chemical composition combine.

Valence

The combining capacity of an atom, determined by the number of electrons residing in its outermost shell.

Ionic Bonding

A type of chemical bond created when one or more electrons transfer directly from one atom to another atom.

Covalent Bonding

A type of chemical bond where two atoms share electrons that orbit around both nuclei.

Ionization

The process of removing an orbital electron from an atom, leaving behind an atom carrying a charge equal in magnitude to the difference between its numbers of electrons and protons.

Particulate Radiation

Radiation emitted when an unstable nucleus ejects particles and kinetic energy, ultimately transforming itself into another atom to achieve stability.

Radioactivity

The general term for processes by which unstable nuclei with excess energy release that energy in the form of particles or electromagnetic waves.

Radioisotopes

Radioactive atoms that have the same number of protons but different numbers of neutrons.

Beta Emission

A radioactive decay process during which an electron, created in an unstable nucleus (not originating in the electron shell), is ejected.

Gamma Emission

The release of gamma rays from an unstable nucleus, defined as a stream of mass-free energy bundles called photons.

Half-Life

The specific duration of time required for a quantity of radioactivity in a radioisotope to decay to one-half of its original value.

Electromagnetic Radiation

An electric and magnetic disturbance traveling through space at the speed of light.

Photon

The smallest quantity of any type of electromagnetic energy, traveling through space as a massless energy disturbance at the speed of light.

Speed of Light ($c$)

The constant speed at which all electromagnetic energy travels in space, equal to $3 \times 10^8\,\text{m/s}$ (or $186,282\,\text{miles per second}$ / $186,000\,\text{miles per second}$).

Amplitude

One-half the total range from crest to valley in a sine wave model, representing the peak energy field intensity.

Frequency ($f$)

The number of wave cycles or oscillations that pass a fixed observation point in one second, measured in hertz ($\text{Hz}$) where $1\,\text{Hz} = 1\,\text{cycle per second}$.

Wavelength ($\lambda$)

The physical distance measured from one crest to the next, from one valley to the next, or between any two identical points on a sine wave.

Wave Equation

The mathematical formula expressing the relationship between velocity, frequency, and wavelength: Velocity = Frequency $\times$ Wavelength, written as $v = f\lambda$ (or $c = f\lambda$).

Electromagnetic Spectrum

The entire range of radiated energies spanning frequencies from $10^2\,\text{Hz}$ to $10^{24}\,\text{Hz}$, divided into visible light, radiofrequency, and x-ray/gamma radiation regions.

Wave-Particle Duality

The phenomenon where electromagnetic radiation exhibits characteristics of both waves and particles; higher-energy photons act more like particles, whereas lower-energy photons act more like waves.

Origin of X-rays vs. Gamma Rays

The sole structural difference between x-rays and gamma rays: x-rays originate in the electron shells of an atom, whereas gamma rays originate within the nucleus.