Atomic and Nuclear Phenomena

Question 1

the photoelectric effect

Answer 1

the ejection of an electron from the surface of a metal in response to light, normally high frequency light

Question 2

current

Answer 2

net charge flow per unit time

Question 3

threshold frequency f(t)

Answer 3

the minimum light frequency necessary to eject an electron from a given metal; depends on the type of metal being exposed to the radiation

Question 4

energy of a photon of light

Answer 4

E=hf

E=energy of the photon of light
h=Planck’s constant (6.626 x 10^-34 J s)
f= is the frequency of the light

Question 5

maximum kinetic energy of an electron in the photoelectric effect

Answer 5

Kmax=hf-W

W=work function of the metal in question

Question 6

work function

Answer 6

the minimum energy required to eject an electron and is related to threshold frequency of that metal

W=h(f(t))

f(t)= threshold frequency

Question 7

fluorescence

Answer 7

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

Question 8

mass defect

Answer 8

the difference between the mass of the unbounded nucleons and the mass of the bonded nucleons within the nucleus; the amount of mass converted to energy during nuclear fusion

Question 9

mass defect and energy

Answer 9

E=mc^2

E=energy
m=mass contributed by the binding energy of the nucleus
c=speed of light

Question 10

nucleons

Answer 10

protons and neutrons

Question 11

what is the most stable kind of nucleus?

Answer 11

intermediate in size are the most stable (Iron), in comparison to small or large nuclei

Question 12

binding energy

Answer 12

the energy that originated from mass defect, the energy released from protons and neutrons bind together

Question 13

fusion

Answer 13

occurs when small nuclei combine into larger nuclei

Question 14

fission

Answer 14

occurs when a large nucleus splits into smaller nuclei

Question 15

why is energy released in fission and fusion

Answer 15

the nuclei formed in both processes are more stable then the starting nuclei

Question 16

radioactive decay

Answer 16

the loss of small particles from the nucleus

Question 17

alpha decay

Answer 17

the emission of an alpha particle which is a helium nucleus, has zero electrons, 2 protons and 2 neutrons; carries double the charge of a beta particle and is much bigger; does not penetrate shielding

Question 18

beta-negative decay

Answer 18

the decay of a neutron into a proton, with emission of an electron and an antineutrino; more penetrating then alpha particles

Question 19

beta-positive decay

Answer 19

also called positron emission, the decay of a proton into a neutron, with emission of a positron (a particle with the size of an electron but with a positive charge) and a neutrino; more penetrating then alpha particles

Question 20

Gamma decay

Answer 20

the emission of a gamma ray, which converts a high-energy nucleus into a more stable nucleus

Question 21

electron capture

Answer 21

the absorption of an electron from the inner shell that combines with a proton in the nucleus to form a neutron

Question 22

half-life (T 1/2)

Answer 22

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

Question 23

exponential decay

Answer 23

the rate at which radioactive nuclei decay is proportional to the number of nuclei that remain

n= (no)e^-(lambda)t

no= the number of undecayed nuclei at time t=0

Question 24

rate of nuclear decay

Answer 24

delta n/ delta t= -lambda(n)

n=number of radioactive nuclei that have not yet decayed in a sample
lambda= decay constant

Question 25

decay constant (lambda)

Answer 25

lambda= ln2/T-half= 0.693/T-half