Atomic Theory and Quantum Mechanics - Vocabulary Notes

Vocabulary flashcards covering key terms from the lecture notes on atomic structure and quantum mechanics.

Angular momentum quantum number (l)

Describes the shape of an orbital; determines subshell type (s, p, d, f).

Anion

A negatively charged ion (more electrons than protons).

Atom

The smallest unit of matter that retains the properties of an element.

Atomic number

The number of protons in the nucleus of an atom; defines the element.

Average atomic mass (atomic weight)

The weighted average of all naturally occurring isotopes of an element.

Avogadro's number

6.022 × 10^23; the number of particles (atoms, molecules, ions) in 1 mole of a substance.

Boundary surface (contour surface or representation)

A 3D region around a nucleus where there is high probability of finding an electron.

Cation

A positively charged ion (more protons than electrons).

Chemistry

The study of matter, its properties, and how it changes.

Compound

A pure substance made of two or more elements chemically bonded.

Contour representation

A diagram showing regions of high probability for electrons in an atom.

De Broglie wavelength

The wavelength associated with a particle; shows matter has wave-like behavior.

Degenerate

Orbitals that have the same energy level.

Density

Mass per unit volume of a substance (ρ = m/V).

Electron density

The probability of finding an electron in a specific region of space.

Electronic structure

The arrangement of electrons in an atom’s orbitals.

Electromagnetic radiation

Energy transmitted as waves, including light, radio, X-rays, etc.

Electrons

Negatively charged subatomic particles found outside the nucleus.

Element

A pure substance consisting of only one type of atom.

Energy

The capacity to do work or transfer heat.

Frequency (of a wave)

Number of wave cycles per second, measured in hertz (Hz).

Chemical formula

Represents the elements and number of atoms in a compound.

Ion

An atom or group of atoms with a net charge.

Isotope

Atoms of the same element with different numbers of neutrons.

Kinetic energy

Energy of motion.

Law of Definite Proportions

A compound always contains the same proportion of elements by mass.

Magnetic quantum number (m_l)

Specifies the orientation of an orbital in space.

Mass

The amount of matter in an object.

Matter

Anything that has mass and takes up space.

Metric System (and relevant prefixes)

A decimal-based measurement system (kilo-, centi-, milli-, etc.).

Molar mass

Mass of one mole of a substance (g/mol).

Mole

The amount of substance containing Avogadro’s number of particles.

Molecule

Two or more atoms bonded together.

Momentum (linear)

Product of mass and velocity of an object.

Node

A point in an orbital where the probability of finding an electron is zero.

Neutron

Neutral subatomic particle found in the nucleus.

Nucleus

Dense center of the atom containing protons and neutrons.

Orbital (not orbit)

Region of space where an electron is likely to be found.

Orbital names (s, p, d, f)

Types of orbitals: s (sphere), p (dumbbell), d (clover), f (complex).

Particulate Model of Matter

Represents matter as made of small particles (atoms, molecules, ions).

Photoelectric effect

Emission of electrons from a material when light shines on it.

Planck’s constant (h)

A fundamental constant (6.626 × 10^-34 J·s) linking energy and frequency.

Potential energy

Stored energy due to position or arrangement.

Planck-Einstein relationship

Energy of a photon: E = hν.

Principal quantum number (n)

Specifies the energy level (shell) of an electron.

Probability density (ψ²)

Mathematical function giving likelihood of finding an electron in space.

Protons

Positively charged subatomic particles in the nucleus.

Quantum, quantized, quanta

Energy comes in discrete packets (quanta), not continuous amounts.

Quantum mechanics

Theory describing behavior of particles at atomic/subatomic scale.

Quantum numbers

Set of numbers (n, l, ml, ms) describing electron properties.

Radial (probability) function

Function showing how electron density varies with distance from nucleus.

Schrödinger’s equation

Mathematical equation that describes wave behavior of electrons.

Electron shell

Group of orbitals with the same principal quantum number n.

Electron subshell

Group of orbitals with the same n and l (e.g., 2p, 3d).

SI Units

International system of measurement (meter, kilogram, second, mole, etc.).

Spectroscopy

Study of interaction between matter and electromagnetic radiation.

Spectrum (spectra)

Range of wavelengths of electromagnetic radiation.

Subatomic particles

Particles smaller than atoms: protons, neutrons, electrons.

Submicroscopic scale

Scale at which atoms and molecules are observed.

Velocity

Speed of an object in a given direction.

Volume

Amount of space an object occupies.

Wave

A disturbance that transfers energy through space or matter.

Wavefunction (ψ)

Mathematical description of an electron’s quantum state.

Wave-particle duality

Concept that particles (like electrons) can behave as both waves and particles.

Wavelength (λ)

Distance between two consecutive wave peaks or troughs.