Atomic and Nuclear Phenomena

Question 1

Photoelectric effect

Answer 1

When light of sufficiently high frequency is incident on metal in a vacuum, the metal emits electrons

Question 2

When light’s frequency is above the threshold frequency of metal, the magnitude of the resulting current is

Answer 2

Directly proportional to the intensity/amplitude of the light

Question 3

Threshold frequency (fT)

Answer 3

The minimum frequency of light that causes ejection of elections

Question 4

Energy of a photon

Answer 4

E=hf

Question 5

Maximum kinetic energy of ejected electron

Answer 5

Kmax=hf-W

W= Work function of metal

Question 6

Work function

Answer 6

Minimum energy required to eject electron

W=hfT

Question 7

Fluorescence

Answer 7

If a flurescent substance is excited with UV light, it will glow
Light returns to original state in 2+ steps which involves less energy, and lower frequency photon is emitted (sometimes within visible)

Question 8

Mass defect

Answer 8

Mass of a nucleus is smaller than protons and neutrons due to E=mc^2
Small mass emits huge energy

Question 9

Strong nuclear force

Answer 9

Attraction of replusive electromagnetic forces that overcomes repulsion of protons

Question 10

Nucleon

Answer 10

protons and neutron

Question 11

Binding energy

Answer 11

Nucleons must get close together and bonded system has lower energy than unbonded system
E=mc^2

Question 12

Weak nuclear force

Answer 12

a lot less strong than strong nuclear forces

Question 13

Mass defect is

Answer 13

The mass contributed by the binding energy in the nucleus

Question 14

Binding energy is greatest for

Answer 14

Intermediate sized atoms

Question 15

Isotopic notation

Answer 15

Atomic number (protons) bottom
Mass number (protons + neutrons) top

Question 16

Fusion

Answer 16

When small nuclei combine to form larger nucleus

Question 17

Fission

Answer 17

Large nucleus splits into smaller nucleus, rarely spontaneous
Induced by absorption of low energy neutron

Question 18

Radioactive decay

Answer 18

Spontaneous decay of nuclei emitting particles

Question 19

Alpha decay

Answer 19

emission of a-particle which is 4,2He nucleus (2 protons, 2 neutrons, 0 electrons)
Carries a double charge
Do not penetrate shielding and interact with matter easily

Question 20

Charge of alpha particles

Answer 20

+2

Question 21

What will alpha particles cause a loss of

Answer 21

4 from mass number

2 from atomic number

Question 22

Beta decay

Answer 22

B-particle is an electron

Emitted when a neutrons decays into a proton and antineutrino

Question 23

What does a neutron decays into

Answer 23

Proton and antineutrino (v)

Question 24

Is b radiation penetrating?

Answer 24

Yes

Question 25

Positron

Answer 25

Mass of electron,but has a positive charge also a neutrino

Question 26

B emission causes

Answer 26

Addition of proton to atomic number

Question 27

During positron emission

Answer 27

Mass number will be less the positrons emitted

Question 28

Gamma decay

Answer 28

Gamma ray emitted (high energy photons0

No change in mass number or atomic number

Question 29

Electron capture

Answer 29

Reverse B- decay
Forms a proton from neutron to emit
Atomic number -1

Question 30

Rate of nuclei decay

Answer 30

Delta(n)/Delta (t)=-(decay constant)(n)

Question 31

Exponential decay

Answer 31

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

Question 32

Decay constant

Answer 32

0.693/half life

Question 33

How to find mass defect for e=mc^2

Answer 33

mulitply amu amount times the amount of protons and neutrons
Add together and subtract isotope nucleus weight