Nuclear Physics

strong nuclear force

happens with neutrons

strong nuclear force

holds protons close

strong nuclear force

stronger than electromagnetic force at short range

strong nuclear force

effective range: 10^-15 m (big-nucleus-sized)

weak nuclear force

changes quarks spin

weak nuclear force

makes fission, fusion, and decay happen

weak nuclear force

turns neutrons into protons or vice versa

weak nuclear force

effective range: 10^-18 m (proton-sized)

atomic number

tells how many protons an atom has

mass number

tells how many protons and neutrons a specific atom has

neutrons in the nucleus

(mass number)-(atomic number)

isotopes

two or more versions of the same element where the atomic number is the same but the number of neutrons is different

Why do nuclei decay?

-too many n:p

-too many p:n

-too big

-too much nuclear potential energy

alpha particle charge

2+

alpha particle composition

2 protons and 2 neutrons

alpha particle effect on mass number/ an

4 down, 2 down

beta particle charge

1-

beta particle composition

electron

beta particle effect on atomic number

1 up

positron charge

1+

positron composition

positron (anti- electron)

positron effect on atomic number

1 down

gamma ray charge

0

gamma ray composition

electromagnetic radiation

gamma ray effect on atomic number

none

Geiger-Marsden experiment

provides evidence for a dense positively charged nucleus

neutron capture

nucleus captures a slow moving neutron and becomes unstable

moderator

slows neutrons with heavy water (²H₂0)

nuclear chain reaction

fission →3 N → each fissions → cycle repeats

control rod

lowered into reactor to absorb neutrons

shielding

lead, thick concrete keeps radiation in

heat exchanger

cools the water without contaminating river water

coal vs. nuclear differences

coal uses 14,000 tons per day, nuclear uses 3kg

mass is…

a form of energy

products of nuclear decay and nuclear fission are…

unstable and radioactive

decay chain ends

at lead (Pb).

Iron (⁵⁶Fe)

lowest energy nucleus