alpha, beta and gamma decay — VCE physics year 11, live

Alpha, beta and gamma decay

An unstable nucleus becomes more stable by emitting radiation. Alpha decay throws out a helium nucleus, beta decay throws out an electron (β−) or a positron (β+) as a neutron and proton swap, and gamma emission releases a high-energy photon. In every nuclear equation the mass numbers and the atomic numbers each balance on both sides, so the emission tells you exactly which element is left behind. This is the real knowscape from knowhere, not a picture of one. Drag it. Watch what actually changes.

physics · nuclear energy · alpha, beta and gamma decaydrag it · it is yours

why this one carries the topic.

Every nucleus here is chasing a tighter grip. Unstable ones throw out alpha, beta or gamma, heavy ones split, light ones fuse, and each step ends more tightly bound and slightly lighter. That missing mass is the energy, via E=mc², whether it runs a reactor or hits your cells.

A nucleus fires an alpha particle, a beta-minus electron, a beta-plus positron or a gamma photon at paper, aluminium and lead. The nuclear equation above it fills in the daughter element as the mass and atomic numbers balance, and each emission stops where its penetrating power runs out.

five things, not forty.

Alpha (α) is a helium nucleus, ⁴₂He: charge +2, heavy, strongly ionising and stopped by paper; the nucleus loses 4 from A and 2 from Z.

Beta-minus (β−) is an electron, ⁰₋₁e, made when a neutron becomes a proton: Z rises by 1, A is unchanged, and an antineutrino is also emitted.

Beta-plus (β+) is a positron, ⁰₊₁e, made when a proton becomes a neutron: Z falls by 1, A is unchanged, and a neutrino is also emitted.

Beta particles carry charge −1 or +1 and almost no mass; they are moderately ionising and stopped by a few millimetres of aluminium.

Gamma (γ) is a high-energy photon with no charge or mass: weakly ionising, only reduced by thick lead, and it changes neither A nor Z.

Balanced nuclear equations work the same for natural (U-238, C-14) and human-made (F-18, Tc-99m) radioisotopes: A and Z each total the same on both sides.

nothing here is a standalone fact.

knowhere maps every concept to what it rests on and what rests on it — 3 underneath this one, 2 built on top. Each one says why, in a sentence, not as an arrow on a diagram.

this conceptalpha, beta and gamma decayA nucleus fires an alpha particle, a beta-minus electron, a beta-plus positron or a gamma photon at paper, aluminium and lead.

sits under itprotons, neutrons and isotopesbecause Decay equations track protons and neutrons through mass and atomic numbers, so isotope notation must come first.

sits under ittrends across the periodic tablebecause Naming the daughter means finding the element with the new atomic number on the periodic table.

sits under itelectromagnetic radiation and the electromagnetic spectrumbecause Gamma rays are high-energy photons at the far end of the electromagnetic spectrum.

built on itdecay series and the band of stabilitybecause Each arrow is one alpha or beta decay, so how they change A and Z must come first.

built on itradiation dose: gray, sievert and the bodybecause Dose depends on how strongly alpha, beta and gamma ionise and how far each travels, which comes from the decay types.

they don't read it. they run it.

Every HSC and VCE concept in knowhere is built like this one — mapped to your curriculum, never capped by it. Free for a week. No lock-in, cancel inside the week and pay nothing.

Free for a week, then a plan you can stop any time.

not your card? send it to whoever's is.

why this one carries the topic.

five things, not forty.

nothing here is a standalone fact.

2 more, same treatment.

they don't read it. they run it.