Structure of Atom Vocabulary Flashcards

Comprehensive vocabulary flashcards covering atomic structure, subatomic particles, atomic models, electromagnetic radiation parameters, quantum numbers, and electron configuration rules.

Nucleons

Subatomic particles, specifically protons and neutrons, that are present inside the atomic nucleus.

Cathode Rays

A stream of very small, negatively charged particles discovered by J. J. Thomson that are $1837$ times lighter than a hydrogen atom and present in all atoms.

Atomic Number ($Z$)

The total number of protons present in the nucleus of an atom, which dictates the chemical identity of an element.

Atomic Mass Number ($A$)

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

Nuclide

An atom or nucleus having a unique composition specified by an element symbol ($X$) along with its atomic mass number ($A$) and atomic number ($Z$).

Isotopes

Individual nuclides of the same element that have identical numbers of protons (atomic number) but different numbers of neutrons in their nuclei.

Isobars

Atoms of different chemical elements having the same mass number ($A$) but different atomic numbers ($Z$).

Isotones

Atoms of different chemical elements that contain the same number of neutrons in their nuclei.

Wavelength ($\lambda$)

The distance between two consecutive crests or troughs in an electromagnetic wave, measured in meters ($m$).

Frequency ($\nu$)

The number of electromagnetic waves that pass a given fixed point in one second, expressed in Hertz ($Hz$ or $s^{-1}$).

Wavenumber ($\bar{\nu}$)

The number of wavelengths per unit length, represented by $\bar{\nu} = \frac{1}{\lambda}$ with the SI unit $m^{-1}$.

Amplitude ($A$)

The height of a wave crest, where the square of this value denotes the overall intensity of the radiation.

Quantum

The smallest discrete quantity of energy that can be emitted or absorbed in the form of electromagnetic radiation.

Planck's Constant ($h$)

The proportionality constant relating the energy of a quantum to its frequency, having a value of $6.626 \times 10^{-34}\,J\,s$.

Photon

A particle-like packet of electromagnetic radiation carrying energy equal to $E = h\nu$, possessing zero rest mass.

Emission Spectrum

The spectrum recorded when radiation is emitted by a species that has previously absorbed energy and reached an excited state.

Balmer Series

A series of spectral emission lines for atomic hydrogen in the visible region of electromagnetic radiation.

Rydberg Constant ($R_H$)

An empirical constant for hydrogen spectral lines, equal to $109677\,cm^{-1}$ or $2.18 \times 10^{-18}\,J$.

Bohr Frequency Rule

The rule stating that the frequency of absorbed or emitted radiation during a transition between stationary states is $\nu = \frac{\Delta E}{h} = \frac{E_2 - E_1}{h}$.

Bohr Radius ($a_0$)

The radius of the first allowed stationary state (orbit) of a hydrogen atom, equal to $52.9\,pm$.

Zeeman Effect

The splitting of atomic spectral lines in the presence of an external magnetic field.

Stark Effect

The splitting of atomic spectral lines in the presence of an external electric field.

Heisenberg Uncertainty Principle

A fundamental principle stating that it is impossible to determine simultaneously the exact position and exact momentum (or velocity) of an electron.

Schrödinger Wave Equation

The foundational quantum mechanical equation $\hat{H}\psi = E\psi$ describing electron wave motion and energy in an atom.

Hamiltonian ($\hat{H}$)

The mathematical operator used in the Schrödinger wave equation to represent the total energy of a quantum mechanical system.

Principal Quantum Number ($n$)

A positive integer ($n = 1, 2, 3, \dots$) that identifies the main electron shell and determines orbital size and general energy level.

Azimuthal Quantum Number ($l$)

Also called subsidiary quantum number; it defines the subshell ($s, p, d, f$) and shape of the orbital, ranging from $0$ to $(n - 1)$.

Magnetic Orbital Quantum Number ($m_l$)

A quantum number specifying the spatial orientation of an orbital within a given subshell, taking $(2l + 1)$ values from $-l$ to $+l$.

Electron Spin Quantum Number ($m_s$)

A quantum number indicating the intrinsic spin orientation of an electron inside an orbital, taking values of $+\frac{1}{2}$ or $-\frac{1}{2}$.

Nodal Plane

A surface or plane passing through the nucleus of an atom where the probability density $\psi^2$ of finding an electron is zero.

Degenerate Orbitals

Atomic orbitals belonging to the same subshell that possess identical energy levels despite having different spatial orientations.

Aufbau Principle

The principle stating that electrons in an atom's ground state sequentially fill atomic orbitals in order of increasing energy level.

Pauli Exclusion Principle

The rule stating that no two electrons in the same atom can possess identical sets of all four quantum numbers.

Hund's Rule of Maximum Multiplicity

The rule establishing that electron pairing in degenerate orbitals within a subshell does not occur until each orbital is singly occupied.

Isoelectronic Species

Atoms and ions that possess the exact same total number of electrons and identical ground-state electronic configurations.