Chemistry 101: Atomic Structure and Periodic Trends Vocabulary

Comprehensive vocabulary flashcards covering atomic theory, quantum mechanics, electromagnetic radiation, quantum numbers, electron configurations, and periodic trends based on pre-lecture notes.

Principal Quantum Number ($n$)

A quantum number that indicates the main energy level and size of an orbital, taking positive integer values ($n = 1, 2, 3, \dots$).

Angular Momentum Quantum Number ($l$)

A quantum number that determines the shape of an orbital, taking integer values from $0$ to $n - 1$ corresponding to $s$, $p$, $d$, and $f$ subshells.

Magnetic Quantum Number ($m_l$)

A quantum number that defines the spatial orientation of an orbital, taking integer values from $-l$ to $+l$.

Spin Quantum Number ($m_s$)

A quantum number describing the direction of an electron's intrinsic spin, taking values of $+\frac{1}{2}$ or $-\frac{1}{2}$.

Pauli Exclusion Principle

The principle stating that no two electrons in an atom can have the exact same set of four quantum numbers, meaning an orbital can hold a maximum of two electrons with opposite spins.

Aufbau Principle

The conceptual process of filling an atom's orbitals by adding electrons sequentially to the lowest available energy orbital.

Hund's Rule

The rule stating that when degenerate orbitals of equal energy are available, electrons occupy them singly with parallel spins before pairing.

Effective Nuclear Charge ($Z_{\text{eff}}$)

The net positive nuclear charge experienced by an electron in a many-electron atom after accounting for shielding by inner electrons, defined as $Z_{\text{eff}} = Z - S$.

Shielding

The reduction of the full nuclear attraction on outer electrons caused by electrostatic repulsions from inner core electrons.

Penetration

The ability of an electron in a given orbital to approach close to the nucleus, increasing nuclear attraction, decreasing shielding, and splitting energy levels into $s < p < d < f$.

Paramagnetic

Describing a substance that contains one or more unpaired electrons, causing it to be attracted to an external magnetic field.

Diamagnetic

Describing a substance in which all electrons are paired, causing it to be weakly repelled by an external magnetic field.

Metallic Radius

One-half the shortest distance between the nuclei of adjacent individual atoms in a crystal lattice of a metallic element.

Covalent Radius

One-half the shortest distance between the nuclei of identical bonded atoms in a covalent molecule.

Ionization Energy ($IE$)

The energy required to completely remove an electron from an isolated gaseous atom or ion.

Electron Affinity ($EA$)

The energy change that occurs when an electron is added to an isolated gaseous atom or ion.

Basic Oxide

A metal oxide (or base anhydride) that reacts with water to yield a basic solution containing hydroxide ions.

Acidic Oxide

A nonmetal oxide (or acid anhydride) that reacts with water to yield an acidic solution containing hydronium ions.

Amphoteric Oxide

An oxide that exhibits both acidic and basic properties and can react with both acids and bases.

Spectroscopy

The study of the interaction between matter and electromagnetic radiation.

Electromagnetic Radiation

A form of energy consisting of oscillating electric and magnetic fields traveling through a vacuum at the speed of light ($c = 2.998 \times 10^8\,\text{m/s}$).

Wavelength ($\lambda$)

The distance between two consecutive crests or troughs of a wave, measured in meters ($\text{m}$), centimeters ($\text{cm}$), nanometers ($\text{nm}$), or angstroms ($\text{\AA} = 10^{-10}\,\text{m}$).

Frequency ($\nu$)

The number of complete wave cycles that pass a given point per unit time, expressed in units of $\text{s}^{-1}$ or Hertz ($\text{Hz}$).

Amplitude ($a$)

The height of a wave crest or depth of a trough, which is directly proportional to the intensity of the radiation.

Refraction

The change in speed and consequent bending of a wave's path when passing from one medium into another.

Diffraction

The bending of a wave around the edges of an obstacle or small opening, producing interference patterns.

Blackbody Radiation

The electromagnetic radiation emitted across a continuous spectrum by a heated solid object.

Planck's Constant ($h$)

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

Quantum

A discrete, fixed packet of energy absorbed or emitted by matter, given by $E = h\nu$.

Photoelectric Effect

The emission of electrons from a metal surface when exposed to electromagnetic radiation at or above a threshold frequency.

Photon

A discrete particle or quantum of light energy carrying an energy of $E_{\text{photon}} = h\nu = \frac{hc}{\lambda}$.

Work Function ($\Phi$)

The minimum energy required to liberate an electron from the surface of a specific metal.

Line Spectrum

A series of discrete fine lines of specific wavelengths emitted by excited gas-phase atoms when electrons transition between energy levels.

Rydberg Equation

An empirical formula predicting line spectrum wavelengths for hydrogen: $\frac{1}{\lambda} = R\left(\frac{1}{n_1^2} - \frac{1}{n_2^2}\right)$, where $R = 1.097 \times 10^7\,\text{m}^{-1}$.

Ground State

The lowest energy state of an atom, where all electrons occupy orbitals of the lowest possible energy ($n = 1$).

Excited State

Any state of an atom with higher energy than the ground state, occurring when an electron absorbs energy and moves to an orbit with $n > 1$.

de Broglie Wavelength

The wavelength associated with a moving particle of mass $m$ and velocity $v$, expressed as $\lambda = \frac{h}{p} = \frac{h}{mv}$.

Heisenberg Uncertainty Principle

The fundamental limit stating that it is impossible to simultaneously measure both the exact position ($\Delta x$) and momentum ($\Delta p$) of a particle: $\Delta x \cdot \Delta p \ge \frac{h}{4\pi}$.

Wavefunction ($\psi$)

A mathematical solution to the Schrödinger equation describing the wave properties and state of an electron in an atom.

Electron Probability Density ($\psi^2$)

The square of the wavefunction, representing the probability per unit volume of finding an electron at a specific position near the nucleus.

Radial Node

A spherical surface at a specific distance $r$ from the nucleus where the electron probability density drops to zero ($\psi^2 = 0$), given by $n - l - 1$.

Angular Node

A planar or conical surface passing through the nucleus where the probability density is zero, with the total number of angular nodes equal to $l$.

Law of Conservation of Mass

The mass law stating that the total mass of materials present after a chemical reaction is identical to the total mass before the reaction.

Law of Definite Composition

The mass law stating that a pure compound always consists of the same elements combined in the exact same proportions by mass.

Law of Multiple Proportions

The mass law stating that when two elements form two different compounds, the masses of one element combining with a fixed mass of the other are in ratios of small whole numbers.

Cathode Rays

Streams of negatively charged particles (electrons) emitted from the negative electrode in an evacuated glass discharge tube under high electric potential.

Atomic Number ($Z$)

The total number of protons contained in the nucleus of an atom, defining the identity of a chemical element.

Mass Number ($A$)

An integer representing the total sum of protons ($Z$) and neutrons ($n^0$) in an atomic nucleus.

Isotopes

Atoms of the same element having identical atomic numbers ($Z$) but different mass numbers ($A$) due to varying numbers of neutrons.

Oxyanion

A polyatomic anion containing a nonmetal or transition metal atom covalently bonded to one or more oxygen atoms.

Binary Acid

An aqueous acid composed of hydrogen and a single nonmetallic element, named using the prefix 'hydro-' and ending in '-ic acid'.

Oxyacid

An acid containing hydrogen, oxygen, and another central element, named according to the suffix of its corresponding polyatomic oxyanion.

Periodic Law

The principle formulated by Mendeleev stating that physical and chemical properties of elements recur periodically when elements are arranged in order of increasing atomic number.