Chapter 7 Vocab

Question 1

Electromagnetic radiation (also electromagnetic energy or radiant energy)

Answer 1

Oscillating, perpendicular electric and magnetic fields moving simultaneously through space as waves and manifested as visible light, x-rays, microwaves, radio waves, and so on.

Question 2

Frequency (ν)

Answer 2

The number of complete waves, or cycles, that pass a given point per second, expressed in units of 1/second, or s^-1 [also called hertz (Hz)]; related inversely to wavelength.

Question 3

Wavelength (λ)

Answer 3

The distance between any point on a wave and the corresponding point on the next wave, that is, the distance a wave travels during one cycle.

Question 4

Speed of light (c)

Answer 4

A fundamental constant giving the speed at which electromagnetic radiation travels in a vacuum; c = 2.99792458 x 10^8 m/s.

Question 5

Amplitude

Answer 5

The height of the crest (or depth of the trough) of a wave; related to the intensity of the energy (brightness of the light).

Question 6

Electromagnetic spectrum

Answer 6

The continuum of radiant energy arranged in order of increasing wavelength.

Question 7

Ultraviolet (UV)

Answer 7

Radiation in the region of the electromagnetic spectrum between the visible and the x-ray regions.

Question 8

Infrared (IR)

Answer 8

The region of the electromagnetic spectrum between the microwave and visible regions.

Question 9

Refraction

Answer 9

A phenomenon in which a wave changes its speed and therefore its direction as it passes through a phase boundary into a different medium.

Question 10

Diffraction

Answer 10

The phenomenon in which a wave striking the edge of an object bends around it. A wave passing through a slit as wide as its wavelength forms a circular wave.

Question 11

Quantum number

Answer 11

A number that specifies a property of an orbital or an electron.

Question 12

Planck’s constant (h)

Answer 12

A proportionality constant relation the energy and frequency of a photon, equal to 6.62607015 x 10^-34 J⋅s.

Question 13

Quantum

Answer 13

A packet of energy equal to hν. The smallest quantity of energy that can be emitted or absorbed.

Question 14

Photoelectric effect

Answer 14

The observation that, when monochromatic light of sufficient frequency shines on a metal, an electric current is produced.

Question 15

Photon

Answer 15

A quantum of electromagnetic radiation.

Question 16

Line spectrum

Answer 16

A series of separated lines of different colors representing photons whose wavelengths are characteristic of an element (see also emission spectrum).

Question 17

Stationary state

Answer 17

In the Bohr model, one of the allowable energy levels of the atom in which it does not release or absorb energy.

Question 18

Ground state

Answer 18

The electron configuration of an atom (or ion or molecule) that is lowest in energy.

Question 19

Excited state

Answer 19

Any electron configuration of an atom (or ion or molecule) others than the lowest energy (ground) state.

Question 20

de Broglie wavelength

Answer 20

The wavelength of a moving particle obtained from the de Broglie equation: λ = h/mu.

Question 21

Wave-particle duality

Answer 21

The principle stating that both matter and energy have wavelike and particle-like properties.

Question 22

Uncertainty principle

Answer 22

The principle stated by Heisenberg that it is impossible to know simultaneously the exact position and velocity of a particle; the principle becomes important only for particles of very small mass.

Question 23

Quantum mechanics

Answer 23

The branch of physics that examines the wave nature of objects on the atomic scale.

Question 24

Schrödinger equation

Answer 24

An equation that describes how the electron matter-wave changes in space around the nucleus. Solutions of the equation provide energy states associated with the atomic orbitals.

Question 25

Wave function (ψ)

Answer 25

A mathematical description of the electron’s matter-wave in three dimensions.

Question 26

Atomic orbital

Answer 26

The wave function of an electron in an atom. The term is used qualitatively to mean the region of space in which there is a high probability of finding the electron.

Question 27

Electron cloud depiction

Answer 27

An imaginary representation of an electron’s rapidly changing position around the nucleus over time.

Question 28

Electron density diagram (also electron probability density diagram)

Answer 28

The pictorial representation for a given energy sub level of the quantity ψ^2 (the probability density of the electron lying within a particular tiny volume) as a function of r (distance from the nucleus).

Question 29

Radial probability distribution plot

Answer 29

The graphic depiction of the total probability distribution (sum of ψ^2) of an electron in the region near the nucleus.

Question 30

Probability contour

Answer 30

A shape that defines the volume around an atomic nucleus within which an electron spends a given percentage of its time.

Question 31

Principle quantum number (n)

Answer 31

A positive integer that specifies the energy and relative size of an atomic orbital; a number that specifies an energy level in an atom.

Question 32

Angular momentum quantum number (l)

Answer 32

An integer from 0 to n-1 that is related to the shape of an atomic orbital.

Question 33

Magnetic quantum number (ml)

Answer 33

An integer from -l through 0 to +l that specifies the orientation of an atomic orbital in the three-dimensional space about the nucleus.

Question 34

Level (also shell)

Answer 34

A specific energy state of an atom given by the principal quantum number n.

Question 35

Sublevel (also subshell)

Answer 35

An energy substrate of an atom within a level. Given by the n and l values, the sublevel designates the size and shape of the atomic orbitals.

Question 36

S orbital

Answer 36

An atomic orbital with l = 0.

Question 37

Node

Answer 37

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

Question 38

P orbital

Answer 38

An atomic orbital with l = 1.

Question 39

D orbital

Answer 39

An atomic orbital with l = 2.

Question 40

F orbital

Answer 40

An atomic orbital with l = 3.