Chapter 3: The Quantum-Mechanical Model of the Atom

Question 1

absorption spectrum

Answer 1

A plot of the absorption of light of a sample of matter as a function of wavelength.

Question 2

angular momentum quantum number (l)

Answer 2

An integer that determines the shape of an orbital.

Question 3

binding energy

Answer 3

The energy with which the electron is bound to the metal.

Question 4

complementary properties

Answer 4

Properties that exclue one another; that is, 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.

Question 5

de Broglie relation

Answer 5

The observation that the wavelength of a particle is inversely proportional to its momentum λ = h / mv.

Question 6

destructive interference

Answer 6

The interaction of waves from two sources that are aligned so that the crest of one overlaps the trough of the other, resulting in cancellation.

Question 7

deterministic

Answer 7

A characteristic of the classical laws of motion, which imply that present circumstances determine future events.

Question 8

diffraction

Answer 8

The phenomena by which a wave emerging from an aperture spreads out to form a new wave front.

Question 9

constructive interference

Answer 9

The interaction of waves from two sources that align with overlapping crests, resulting in a wave of greater amplitude.

Question 10

electromagnetic radiation

Answer 10

A form of energy embodied in oscillating electric and magnetic fields.

Question 11

electron spin

Answer 11

A fundamental property of electrons; spin can have a value of ±1/2.

Question 12

emission spectrum

Answer 12

The range of wavelengths emitted by a particular element; used to identify the element.

Question 13

Heisenberg’s uncertainty principle

Answer 13

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.

Question 14

indeterminacy

Answer 14

The principle that present circumstances do not necessarily determine future evens in the quantum-mechanical realm.

Question 15

gamma ray (γ) emission

Answer 15

The form of radioactive decay that occurs when an unstable nucleus emits extremely high-frequency electromagnetic radiation.

Question 16

infrared (IR) radiation

Answer 16

Electromagnetic radiation emitted from warm objects, with wavelengths slightly larger than those of visible light.

Question 17

frequency (v)

Answer 17

For waves, the number of cycles (or complete wavelengths) that pass through a stationary point in one second.

Question 18

interference

Answer 18

The superposition of two or more waves overlapping in space, resulting in either an increase in amplitude (constructive interference) or a decrease in amplitude (destructive interference).

Question 19

magnetic quantum number (m_l)

Answer 19

An integer that specifies the orientation of an orbital.

Question 20

electromagnetic spectrum

Answer 20

The range of the wavelengths of all possible electromagnetic radiation.

Question 21

microwave

Answer 21

Electromagnetic radiation with wavelengths slightly lower than those of infrared radiation; used for radar and in microwave ovens.

Question 22

node

Answer 22

A point where the wave function (

Question 23

orbital

Answer 23

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.

Question 24

phase

Answer 24

With regard to waves and orbitals, the sign of the amplitude of the wave, which can be positive or negative.

Question 25

photoelectric effect

Answer 25

The observation that many metals emit electrons when light falls upon the metal.

Question 26

photon (quantum)

Answer 26

The smallest possible packet of electromagnetic radiation with an energy equal to hv.

Question 27

principal level (shell)

Answer 27

The group of orbitals with the same value of n.

Question 28

principal quantum number (n)

Answer 28

The integer that specifies the overall size and energy of an orbital. The higher the quantum number n, the greater the average distance between the elctron and the nucleus and the higher its energy.

Question 29

probability density

Answer 29

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 (

Question 30

quantum number

Answer 30

One of four interrelated numbers that determine the shape and energy of orbitals, as specified by a solution of the Schrodinger equation.

Question 31

quantum-mechanical model

Answer 31

A model that explains the behavior of absolutely small particles such as electrons and photons.

Question 32

radial distribution function

Answer 32

A mathematical function that represents the total probability of finding the electron within a thin sperical shell at a distance r from the nucleus in an atom.

Question 33

amplitude

Answer 33

The vertical height of a crest (or depth of a trough) of a wave; a measure of wave intensity.

Question 34

radio wave

Answer 34

The form of electromagnetic radiation with the longest wavelengths and smallest energy.

Question 35

spin quantum number (m_s)

Answer 35

The fourth quantum number, which denotes the electron’s spin as either 1/2 (up arrow) or -1/2 (down arrow).

Question 36

sublevel (subshell)

Answer 36

Those orbitals in the same principal level with the same value of n and l.

Question 37

ultraviolet (UV) radiation

Answer 37

Electromagnetic radiation with slightly smaller wavelengths than visible light.

Question 38

visible light

Answer 38

Electromagnetic radiation with frequencies that can be detected by the human eye.

Question 39

wave function

Answer 39

(

Question 40

wavelength (λ)

Answer 40

The distance between adjacent crests of a wave.

Question 41

X-ray

Answer 41

Electromagnetic radiation with wavelenghts slightly longer than those of gamma rays; used to image bones and internal organs.