Atomic and Nuclear Phenomena

Question 1

the ejection of an electron from the surface of a metal in response to light

Answer 1

photoelectric effect

Question 2

the minimum light frequency necessary to eject an electron from a given material

Answer 2

threshold frequency (ƒ(T))

Question 3

light quanta that are present in an integral number in a light beam; have energy proportional to frequency of light

Answer 3

photons

Question 4

relationship of energy to frequency of light:

Answer 4

E = hƒ

where:
E = energy of photon of light
h = Planck’s constant (6.626x10^-34 J*s)
ƒ = frequency of light

Question 5

maximum kinetic energy of ejected electron:

Answer 5

K(max) = hƒ - W

where:
h = Planck’s constant (6.626x10^-34 J*s)
ƒ = frequency of light
W = work function of metal in question

Question 6

the minimum energy necessary to eject an electron from a given metal; its value depends on the metal used and can be calculated by multiplying the threshold frequency by Planck’s constant

Answer 6

work function

Question 7

work function:

Answer 7

W = h ƒ(T)

where:
h = Planck’s constant (6.626x10^-34 J*s)
ƒ(T) = threshold frequency

Question 8

states that electron energy levels are stable and discrete, corresponding to specific orbits

Answer 8

Bohr model of the atom

Question 9

an electron can jump form a lower-energy to a higher-energy orbit by ____ a photon of light of the same frequency as the energy difference between the orbits

Answer 9

atomic absorption (absorbing)

Question 10

when an electron falls from a higher-energy to a lower-energy orbit, it ____ a photon of light of the same frequency as the energy difference between the orbits

Answer 10

atomic emission (emits)

Question 11

may be impacted by small changes in molecular structure

Answer 11

absorption spectra

Question 12

occurs when a species absorbs high-frequency light and then returns to its ground state in multiple steps; each step has less energy than the absorbed light and is within the visible range of the electromagnetic spectrum

Answer 12

fluorescence

Question 13

the amount of energy that is released when nucleons (protons and neutrons) bind together

Answer 13

nuclear binding energy

Question 14

the strong and weak nuclear forces (which contribute to the stability of the nucleus), electrostatic forces, and gravitational forces

Answer 14

four fundamental forces of nature

Question 15

the difference between the mass of the unbonded nucleons and the mass of the bonded nucleons within the nucleus; the unbonded constituents have more energy and, therefore, more mass than the bonded constituents; is the amount of mass converted to energy during nuclear fission

Answer 15

mass defect

Question 16

equivalence of matter and energy:

Answer 16

E = mc^2

where:
E = energy
m = mass
c = speed of light (3x10^8 m/s)

Question 17

isotopic notation

Answer 17

elements are preceded by their atomic number (Z) as a subscript and mass number (A) as a superscript

where:
X = element
A = mass number (corresponds to number of protons plus number of neutrons)
Z = atomic number (corresponds to number of protons)

Question 18

occurs when small nuclei combine into larger nuclei; energy is released because nuclei formed is more stable than starting nuclei

Answer 18

fusion

Question 19

occurs when a large nucleus splits into smaller nuclei; energy is released because nuclei formed is more stable than starting nuclei

Answer 19

fission

Question 20

the loss of small particles from the nucleus; naturally occurring spontaneous decay of certain nuclei accompanied by the emission of specific particles

Answer 20

radioactive decay

Question 21

radioactive decay:
represent nuclear isotopes; parent nucleus __ undergoes nuclear decay to form a daughter nucleus __; sum of atomic numbers and mass numbers must be same on both sides of equation

Answer 21

X and Y

Question 22

radioactive decay:

generic balanced equation:

Answer 22

Question 23

radioactive decay:

the emission of an ____ particle, which is a He nucleus that consists of two protons, two neutrons, and zero electrons

Answer 23

alpha (α) decay

Question 24

radioactive decay:

alpha (α) decay balanced equation:

Answer 24

Question 25

radioactive decay:

the decay of a neutron into a proton, with emission of an electron (e-, __) (Z = -1, A = 0)

Answer 25

beta-negative (β-) decay

Question 26

radioactive decay:

beta-negative (β-) decay balanced equation:

Answer 26

Question 27

radioactive decay:

the decay of a proton into a neutron, with emission of a positron (e+, __) (Z = +1, A = 0)

Answer 27

beta-positive (β+) decay

Question 28

has the mass of an electron but carries a positive charge

Answer 28

positron (e+, β+)

Question 29

radioactive decay:

beta-positive (β+) decay balanced equation:

Answer 29

Question 30

radioactive decay:
the emission of a ____ ray (a high-energy (high-frequency) photon), which converts a high-energy nucleus into a more stable nucleus; carry no charge and simply lower the energy of the parent nucleus without changing the mass number or atomic number

Answer 30

gamma (𝛾) decay

Question 31

radioactive decay:

gamma (𝛾) decay balanced equation:

Answer 31

Question 32

radioactive decay:
the absorption of an electron from the inner shell that combines with a proton in the nucleus to form a neutron; can be thought of as reverse of beta-negative (β-) decay

Answer 32

electron capture

Question 33

radioactive decay:

electron capture balanced equation:

Answer 33

Question 34

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

Answer 34

half-life (T(1/2))

Question 35

how the number of radioactive nuclei changes with time; the rate at which radioactive nuclei decay is proportional to the number of nuclei that remain

Answer 35

exponential decay

Question 36

rate at which nuclei decay:

Answer 36

∆N/∆t = -λn

where:
∆N/∆t = rate at which nuclei decay
λ = decay constant
n = number of radioactive nuclei that have not yet decayed

Question 37

exponential decay:

Answer 37

n = n(o) e^-λt

where:
n = number of radioactive nuclei that have not yet decayed
n(o) = number of undecayed nuclei at time t = 0
λ = decay constant
t = time

Question 38

decay constant relation to half-life:

Answer 38

λ = ln 2 / T(1/2) = .693 / T(1/2)

where:
λ = decay constant
T(1/2) = half-life