1.2 - stable & unstable nuclei

Question 1

what type of particles does strong nuclear force effect

Answer 1

Hadrons

Question 2

What’s the proof for the SNF

Answer 2

gravity is too weak to overcome the electrostatic force of repulsion between protons in the nucleus

Question 3

what do stable isotopes have

Answer 3

nuclei that don’t disintegrate

SNF overcoming electrostatic repulsion between protons in the nucleus

Question 4

what affects the SNF between particles

Answer 4

the distance between the particles

Question 5

force curve

• name 3 fundamental forces
• describe them (what they do and any specific ranges)
• number them from strongest to weakest (1-3)

Answer 5

1) Red = strong nuclear force (attractive at 3 - 4 fm, repulsive <0.5 fm)
2) electrostatic force of repulsion / attraction
3) gravity, virtually no effect but slowly attracts all particles together by their mass (infinite range)

{distance from nucleus}

Question 6

what is the SNF finite range

Answer 6

1x10^-15 m

(atomic nucleus size)

Question 7

what are the 3 main types of radiation emitted from naturally occurring radioactive isotopes

Answer 7

Alpha decay

beta (B-) radiation

gamma radiation

Question 8

describe alpha particles

• what do they consist of, why

Answer 8

⁴₂a

• x2 neutrons , x2 patrons
• stable structure, strong nuclear force > electrostatic force of repulsion from P+

(overall mass makes the strong nuclear force strong enough to overcome the repulsion)

Question 9

What type of isotopes undergo alpha emission

Answer 9

istopes with too large nuclei for the SNF force to act all across it

Question 10

equation of alpha radiation

Answer 10

^A_Z X –> ^A-4_Z-2 Y + ⁴₂a

Question 11

describe the properties of alpha particles

Answer 11

small rage (large particle = lots of collisions)

decrease in concentration drastically the further you move away from the source

Question 12

how to test range if alpha particles

(2)

Answer 12

1) Geiger counter, count rate decreasing as distance increases from the source
2) gas chamber, observe alpha particles tracks, measuring the distance they travel

Question 13

What happens in B- decay

• give the equation too

Answer 13

N —> P+ and an e- is emmited with an atineutrino

^A_ZX = ^A_Z+1Y +⁰_-1B- + V~

B- = Electron

V~ = antineutrino

Question 14

What type of isotope undergoes B- radiation

Answer 14

an unstable one, containing weak nuclear force

Question 15

why are B- particle different to an alpha particle

Answer 15

longer range, since its smaller = fewer collisions

(higher ionization)

Question 16

Define gamma radiation

• what produces this

Answer 16

an electromagnetic wave

• emitted from an unstable nucleus that has too much energy after B- radiation or Alpha emission

Question 17

give the properties of gamma (Y) radiation

Answer 17

no mass

no charge

highly ionizing (travels through thick metal)

infinite range (until colliding )

Question 18

how were neutrinos/antineutrinos hypothesized

Answer 18

if B- decay just emitted an e-, the principle of conservation of energy would be broken so another particle was hypothesized

(energy of the decay didn’t = the Ek of the e- alone)

the particle would have virtually 0 mass (undetected) and 0 charges (conserving charge)

Question 19

how were (anti)neutrinos discovered

Answer 19

detected from a result of them interacting calcium nuclei in a large tank of water

Question 20

give physical properties of (anti)neutrinos

Answer 20

0 mass

0 charge

hardly interact with anything (only another during annihilation)