Chapter 9

Question 1

photoelectric effect

Answer 1

the ejection of electrons from a metal when light (of high enough frequency) hits it

Question 2

threshold frequency

Answer 2

the minimum frequency of light that causes ejection of electrons

(Depends on the type of metal being exposed to the radiation)

Question 3

photon

Answer 3

a particle representing a quantum of light; composes a light beam

Question 4

energy of a photon equation

Answer 4

E = hf

E → photon energy

h → Planck’s constant

f → frequency of light

Question 5

frequency of light equation

Answer 5

c = f λ

c → speed of light

f → frequency

λ → wavelength

Question 6

if the frequency of a photon is at the threshold frequency for the metal…

Answer 6

the electron will just barely escape (with no extra energy)

Question 7

if the frequency of a photon is above the threshold frequency for the metal…

Answer 7

the excess energy will be converted to kinetic energy in the ejected electron

Question 8

maximum kinetic energy of the ejected electron equation

Answer 8

Kmax = hf – W

h = Planck’s constant
f = frequency of light
W = work function of the metal in question

Question 9

Work function (definition and equation)

Answer 9

the minimum energy required to eject an electron

W = hfT

h = Planck’s constant

fT = frequency threshold

Question 10

Atomic absorption

Answer 10

An electron can jump from a lower energy to a higher energy orbit if it absorbs a photon with the same energy as the difference between orbits

Question 11

Atomic emission

Question 12

how does fluorescence work?

Answer 12

the UV radiation excited the molecules to a higher energy state, and then when they return to ground state, they emit photons

Question 13

nucleons

Answer 13

protons and neutrons

Question 14

Mass defect

Answer 14

the apparent loss of mass when protons and neutrons come together and some of the mass is converted to energy

the difference between the mass of the unbonded nucleons and the bonded nucleons within the nucleus

Question 15

Binding energy

Answer 15

the energy released when the nucleons come together

Question 16

isotopic notation

Answer 16

Question 17

Fusion

Answer 17

small nuclei combine to form a larger nucleus

Question 18

Fission

Question 19

radioactive decay

Answer 19

a naturally occurring spontaneous decay of certain nuclei accompanied by the emission of specific particles

Question 20

alpha particle

Answer 20

a helium nucleus (2 protons and 2 neutrons

atomic mass = 4

atomic number = 2

Question 21

alpha decay

Answer 21

an unstable nucleus changes to another element by shooting out an alpha particle

Question 22

positron

Question 23

β- decay

Answer 23

a neutron is converted into a proton and a β- particle (electron) is emitted

Question 24

β+ decay (positron emission)

Answer 24

a proton is converted to a neutron and a β+ particle (positron) is emitted

Question 25

gamma ray

Answer 25

high-energy (high frequency) photons

no charge

Lower the energy of the parent nucleus without changing the mass number or the atomic number

Question 26

Gamma decay

Answer 26

the emission of a gamma ray; the high energy nucleus is converted into a more stable nucleus

Question 27

electron capture

Answer 27

Question 28

half life

Answer 28

the amount of time required for half of a sample of radioactive nuclei to decay