Chapter 7 Vocabulary Flashcards
Quantum-mechanical Model
A model that explains the behavior of absolutely small particles such as electrons and photons.
Electromagnetic Radiation
A form of energy embodied in oscillating electric and magnetic fields.
Amplitude
The vertical height of a crest (or depth of a trough) of a wave; a measure of wave intensity.
Wave length (λ)
The distance between adjacent crests of a wave.
Frequency (ν)
For waves, the number of cycles (or complete wavelengths) that pass through a stationary point in one second.
Electromagnetic spectrum
The range of the wavelengths of all possible electromagnetic radiation.
Gamma (γ) Rays
The form of electromagnetic radiation with the shortest wavelength and highest energy.
X-Rays
Electromagnetic radiation with wavelengths slightly longer than those of gamma rays; used to image bones and internal organs.
Ultraviolet (UV) Radiation
Electromagnetic radiation with slightly smaller wavelengths than visible light.
Visible Light
Those frequencies of electromagnetic radiation that can be detected by the human eye.
Infrared (IR) Radiation
Electromagnetic radiation emitted from warm objects, with wavelengths slightly larger than those of visible light.
Microwaves
Electromagnetic radiation with wavelengths slightly longer than those of infrared radiation; used for radar and in microwave ovens.
Radio Waves
The form of electromagnetic radiation with the longest wavelengths and smallest energy.
Interference
The superposition of two or more waves overlapping in space, resulting in either an increase in amplitude (constructive interference) of a decrease in amplitude (destructive interference).
Constructive Interference
The interaction of wave from two sources that align with overlapping crests, resulting in a wave of greater amplitude.
Destructive Interference
The interaction fo waves from two sources aligned so that the crest of one overlaps the trough of the other, resulting in cancellation.
Diffraction
The phenomena by which a wave emerging from an aperture spreads out to form a new wave front.
Photoelectric Effect
The observation that many metals emit electrons when light falls upon them.
Photon (quantum)
The smallest possible packet of electromagnetic radiation with an energy equal to hv.
Emission Spectrum
The range of wavelengths emitted by a particular element; used to identify the element.
de Broglie Relation
The observation that the wavelength of a particle is inversely proportional to its momentum λ= h/mv
Complementary Properties
Those properties that exclude one another, i.e., the more you know about one, the less you know about the other. For example, the wave nature and particle nature of the electron are complementary.
Heisenberg’s Uncertainty Principle
The principle stating that due to the wave-particle duality, it is fundamentally impossible to precisely determine both the position and velocity of a particle at a given moment in time.
Deterministic
A characteristic of the classical laws of motion, which imply that present circumstances determine future events.
Indeterminacy
The principle that present circumstances do not necessarily determine future events in the quantum-mechanical realm.
Orbital
A probability distribution map, based on the quantum mechanical model of the atom, used to describe the likely position of an electron in an atom; also an allowed energy state for an electron.
Wave Function
A mathematical function that describes the wavelike nature of the electron.
Quantum Number
One of four interrelated numbers that determine the shape and energy of orbitals, as specified by a solution of the Schrodinger equation.
Principal Quantum Number (n)
An integer that specifies the overall size and energy of an orbital. The higher the quantum number n, the greater the average distance between the electron and the nucleus and the higher its energy.
Angular Momentum Quantum Number (l)
An integer that determines the shape of an orbital.
Magnetic Quantum Number (ml)
An integer that specifies the orientation of an orbital.
Principal level (shell)
The group of orbitals with the same value of n.
Sublevel (subshell)
Those orbitals in the same principal level with the same value of n and l.
Probability Density
The probability (per unit volume) of finding the electron at a point in space as expressed by a three-dimensional plot of the wave function squared.
Radial Distribution Function
A function that represents the total probability of finding an electron within a thin spherical shell at a distance r from the nucleus.
Node
A point where the wave function, and therefore the probability density and radial distribution function, all go through zero.
Phase
The sign of the amplitude of a wave; can be positive or negative.
