Chapter 2

Question 1

Photoelectric effect

Answer 1

Metals emit electrons when light shines upon them

Question 2

Electromagnetic spectrum

Answer 2

Low energy, low frequency, long wavelength
High energy, high frequency, short wavelength

Question 3

quantum-mechanical model

Answer 3

a model that explains the strange behavior of electrons

Question 4

wave–particle duality of light

Answer 4

Certain properties of light are best described by thinking of it as a wave, while other properties are best described by thinking of it as a particle

Question 5

electromagnetic radiation

Answer 5

a type of energy embodied in oscillating electric and magnetic fields.

Question 6

Electromagnetic radiation speed in vacume

Answer 6

3 x 10^8 m/s

Question 7

We can characterize a wave by?

Answer 7

amplitude and its wavelength

Question 8

amplitude

Answer 8

the vertical height of a crest

Question 9

wavelength (λ)

Answer 9

the distance between adjacent crests (or any two analogous points) and is measured in units such as meters, micrometers, or nanometers.

Question 10

color

Answer 10

Determined by the wavelength

Question 11

frequency (ν)

Answer 11

the number of cycles (or wave crests) that pass through a stationary point in a given period of time.

Question 12

electromagnetic spectrum

Answer 12

Visible light makes up only a tiny portion of it

Question 13

interference

Answer 13

Waves, including electromagnetic waves, interact with each other in a characteristic way

Question 14

constructive interference.

Answer 14

if two waves of equal amplitude are in phase when they interact—that is, they align with overlapping crests—a wave with twice the amplitude results.

Question 15

destructive interference.

Answer 15

two waves are completely out of phase when they interact—that is, they align so that the crest from one overlaps with the trough from the other

Question 16

diffraction

Answer 16

When a wave encounters an obstacle or a slit that is comparable in size to its wavelength, it bends (or diffracts) around it and results in an interference pattern

Question 17

binding energy

Answer 17

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

Question 18

Relationship between energy and frequence

Answer 18

E = hv (where v is frequence)

Question 19

Photon

Answer 19

A packet of light

Question 20

KE of ejected photon

Answer 20

KE = hv - B.E (B.E is binding energy)

Question 21

emission spectrum

Answer 21

The range of wavelengths emitted by a particular element

Question 22

Niels Bohr

Answer 22

develop a model for the atom that explained atomic spectra. In his model, electrons travel around the nucleus in circular orbits (analogous to those of the planets around the sun). Bohr’s orbits exist only at specific, fixed distances from the nucleus. The energy of each Bohr orbit is also fixed, or quantized. Bohr called these orbits stationary states

Question 23

Electron transition

Answer 23

The energy of the photon emitted when an electron makes a transition from one stationary state to another is the energy difference between the two stationary states. Transitions between stationary states that are closer together, therefore, produce light of lower energy (longer wavelength) than transitions between stationary states that are farther apart.

Question 24

absorption spectrum

Answer 24

dark lines on a bright background

Question 25

electron interference

Answer 25

the interference pattern is not caused by pairs of electrons interfering with each other, but rather by single electrons interfering with themselves.

Question 26

de Broglie relation

Answer 26

The wavelength (λ) of an electron of mass m moving at velocity v

Question 27

The Uncertainty Principle

Answer 27

we cannot simultaneously measure its position and its velocity with infinite precision.

Question 28

complementary properties

Answer 28

Complementary properties exclude one another—the more we know about one, the less we know about the other.

Question 29

Heisenberg’s uncertainty principle

Answer 29

the product of Δx and mΔv must be greater than or equal to a finite number (h/4π).

Question 30

indeterminacy

Answer 30

Unlike a baseball, whose future path is determined by its position and velocity when it leaves the pitcher’s hand, the future path of an electron is indeterminate and can only be described statistically.

Question 31

an orbital

Answer 31

a probability distribution map showing where the electron is likely to be found

Question 32

ψ is the wave function

Answer 32

a mathematical function that describes the wavelike nature of the electron. A plot of the wave function squared represents an orbital, a probability density distribution map of the electron.

Question 33

principal quantum number

Answer 33

n

Question 34

angular momentum quantum number

Answer 34

l

Question 35

magnetic quantum number

Answer 35

m sub l

Question 36

spin quantum number

Answer 36

m sub s (1/2 or -1/2)

Question 37

energy of an electron in an orbital with quantum number n

Answer 37

E = -2.18 * 10^-18 [1/n square final - 1/n square initial]

Question 38

Electron spin

Answer 38

The spin quantum number specifies the orientation of the spin of the electron.

Question 39

principal level (or principal shell)

Answer 39

Electrons with the same value of n

Question 40

sublevel

Answer 40

Orbitals with the same value of n and l

Question 41

probability density

Answer 41

a three-dimensional plot of the wave function squared

Question 42

A node

Answer 42

a point where the wave function (ψ), and therefore the probability density and radial distribution function, all go through zero.