Chapter 4 - Electrons in Atoms

Electromagnetic Radiation

A form of energy that exhibits wavelike behavior as it travels through space.

Wavelength

The shortest distance between equivalent points on a continuous wave (represented by λ, lambda).

Frequency

The number of waves that pass a given point per second (represented by ν, nu).

Amplitude

The wave’s height from the origin to a crest, or from the origin to a trough.

Electromagnetic Spectrum

Includes all forms of electromagnetic radiation, with the only differences being their frequencies and wavelengths.

Quantum

The minimum amount of energy that can be gained or lost by an atom.

Planck’s Constant

Has a value of 6.626 × 10⁻³⁴ J·s, where J (joule) is the energy of a quantum.

Photoelectric Effect

Electrons, called photoelectrons, are emitted from a metal’s surface when light at or above a certain frequency shines on the surface.

Photon

A massless particle that carries a quantum of energy.

Atomic Emission Spectrum

The set of frequencies of the electromagnetic waves emitted by atoms of an element.

Ground State

The lowest allowable energy state of an atom.

Quantum Number

The position, energy, and spin of an electron within an atom.

de Broglie Equation

Describes the wave-like nature of particles, showing that matter can behave like waves.

Heisenberg Uncertainty Principle

States that it is fundamentally impossible to know precisely both the velocity and position of a particle at the same time.

Quantum Mechanical Model of the Atom

The atomic model in which electrons are treated as waves.

Atomic Orbital

Describes the electron’s probable location.

Principle Quantum Number

Indicates the relative size and energy of atomic orbitals.

Principle Energy Level

The major energy level around the nucleus.

Energy Sublevel

Divisions within each principal energy level in an atom.

Electron Configuration

The arrangement of electrons in an atom.

Aufbau Principle

States that each electron occupies the lowest energy orbital available.

Pauli Exclusion Principle

States that a maximum of two electrons can occupy a single atomic orbital, but only if the electrons have opposite spins.

Hund’s Rule

States that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals.

Valence Electron

Electrons in an atom’s outermost orbitals, generally those orbitals associated with the atom’s highest principal energy level.

Electron-Dot Structure

Consists of an element’s symbol, which represents the atomic nucleus and inner-level electrons, surrounded by dots representing all of the atom’s valence electrons.