Physics AS Level - Radioactivity

nucleon number

total number of protons and neutrons

proton/atomic number

total number of protons

isotope

atoms of the same element with a different number of neutrons but the same number of protons

simple model

nucleus: made of protons and neutrons

electrons move around nucleus in a cloud, some closer to and some further from the nucleus

what is a in nuclear notation

nucleon number

what is z in nuclide notation

proton number

what is x in nuclide notation

element

unified atomic mass unit

1 u = 1/12 mass of a carbon-12 atom

during a nuclear process what happens to the nucleon number, proton number and mass-energy

they are all conserved

radioactive processes are ______ and ___________.

random and spontaneous

random in terms of radioactivity

impossible to predict and each nucleus has the same probability of decaying per unit time

spontaneous in terms of radioactivity

not affected by external factors such as the presence of other nuclei, temperature and pressure

evidence on a graph for randomness

graph will have fluctuations in count rate

evidence on a graph for spontaneousness

graph has same shape even at different temperatures, pressure, etc

nature and symbol of an alpha-particle

helium nucleus, 4 (nucleon number) and 2 (proton number) He

nature and symbol of a beta + particle

fast moving positron, 0 (nucleon number), 1 (proton number), e+

nature and symbol of a beta - particle

fast moving electron, 0 (nucleon number), -1 (proton number), e-

nature and symbol of gamma ray

electromagnetic radiation, 0 for both numbers, γ

charge of alpha particle

+2

charge of beta particle

-1

charge of gamma ray

0

relative mass of alpha particle

4

relative mass of a beta particle

1/1840

relative mass of gamma ray

0

speed of alpha particle

slow, 10^6 m/s

speed of a beta particle

fast, 10^8 m/s

speed of a gamma ray

speed of light, 3 × 10^8 m/s

energy of an alpha particle

discrete

energy in beta radiation

continuous range (because anti neutrinos are emitted in beta decay)

what is alpha radiation stopped by

paper

what is beta radiation stopped by

few mm of aluminum

what is gamma radiation stopped by

few cm of lead

ionizing power of alpha particles

high

ionizing power of alpha particles

high

ionizing power of beta particles

low

ionizing power of gamma rays

very low

range of alpha particles

low, few cm

range of beta particles

medium, tens of cm

range of gamma radiation

long, meters

effect of magnetic on alpha

deflected slightly

effect of magnetic on beta particles

deflected greater

effect of magnetic on gamma ray

undeflected

effect of electric on alpha particle

attracted to -ve

effect of electric on beta particles

attracted to ve+

effect of electric on gamma ray

undeflected

force for alpha particle

strong interaction

force for beta particle

weak interaction

what happens in alpha decay

loses a helium nucleus

what happens in beta- decay

neutrons turns into a proton, emitting an electron and electron anti-neutrino

what happens in beta+ decay

proton turns into a neutron and a positron and electron neutrino are emitted

what happens in beta- decay

neutron turns into a proton and an electron and electron antineutrino emitted

what happens in gamma decay

a nucleus changes from a higher energy state to a lower energy state through the emission of electromagnetic radiation (photons)