– Why are alpha- and beta radiation referred as particles, whilst gamma radiation as rays?
In: Physics
alpha radiation is fast moving helium-4 nuclei
beta radiation is fast moving electrons
gamma radiation is short wavelength light
So alpha and beta are particles that have mass, gamma is not. You can consider photons particles if you want, but then you can also consider particles with mass waves.
Alpha radiation is chunks of atomic nucleus being ejected at high speed (really high speed). Beta radiation is electrons being ejected a really high speed. Gamma radiation is light (photons) of a high frequency so they penetrate and deliver (sunburn-like) damage to your internal organs.
Because alpha and Beta literally are particles.
Alpha radiation is literally chunks of atomic nuclei getting flung off as little clumps of protons and neutrons. Beta particles are the same thing but with electrons.
While X and Gamma rays are pure energy.
Per Wikipedia:
> Alpha particles, **also called alpha rays** or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. ([source](https://en.wikipedia.org/wiki/Alpha_particle))
and
> A beta particle, **also called beta ray** or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus, known as beta decay. ([source](https://en.wikipedia.org/wiki/Beta_particle))
Finally, gammay rays consist of high-energy photons:
> A photon (from Ancient Greek φῶς, φωτός (phôs, phōtós) ‘light’) is an **elementary particle** that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. ([source](https://en.wikipedia.org/wiki/Photon))
Emphasis mine.
That said, alpha and beta rays are made from stuff we normally consider matter, whereas gamma rays are electromagnetic radiation, which we don’t. This could explain why it might be more common to emphasize the particle nature of alpha and beta radiation.
All three are made up of particles. The difference is that alpha (4He nuclei) and beta particles (electrons) have mass (and electric charge) while gamma particles (photons) don’t. And while quantum physics tells us that both massed and massless particles are actually “particle-and-wave” and acts as either depending on circumstances, we are more used to interacting with massed particles as particles, and massless particles as waves.
What we colloquially refer to as just “radiation” is actually two physically different things: *electromagnetic* radiation and *nuclear* radiation.
Electromagnetic radiation is just light. Phone screens, lightbulbs, microwaves, Wifi, etc. all emit electromagnetic radiation. The stronger stuff, like UV or **gamma** rays, can be harmful to us. So they colloquially get referred to as “radiation” where Wifi is just “radio waves”.
Nuclear radiation happens when the nucleus of an atom decays into a different element, kicking out a particle in the process. An **alpha** particle is 2 protons and 2 neutrons (aka a helium atom). A **beta** particle is either an electron (when a neutron turns into a proton) or a positron (when a proton turns into a neutron).
Because one is high frequency light, and therfore “ray” describes it, and the other two are forms of nuclear radiation, which is the parts of atoms flying at high speed.
Look at a cloud chamber video. The smoke trails coming off radioactive material are nuclear radiation, and that is what is so dangerous. Particles like that can penetrate your body and collide with your DNA, destroying it. This can happen very rapidly, which is why just being exposed to high levels of radiation is a death sentence, and not a nice one.
Look up “radium girls” for a horrible story and pictures of just how damaging it can be.
Gamma rays are also very dangerous, but thankfully they aren’t created around here very much. You can survive a bit of UV exposure, but I’m not sure you want to try being hit with a gamma ray even for a second.
Alpha and beta particles are actually particles. Alpha particles are helium nuclei, and beta particles are electrons
Gamma radiation is light. While we can think of light as photons, all of these names were established before wave-particle duality was even conceptualized (1923), but after the double slit experiment (1801) showed light was a wave, but it wouldn’t be until 1905 the photon would even be proposed (quantized light was proposed by Max Planck in 1900, but only as a mathematical trick. Planck did not think that was the actual nature of the universe)
Alpha and beta particles were discovered in 1899 by Ernest Rutherford, and gamma radiation was discovered by Paul Villard in 1900
Henri Becquerel discovered radiation in 1896, and discovered that the electron (discovered by JJ Thompson in 1897) had the same mass to charge ratio as the beta particle in 1900
Marie Curie is the one who coined the term radioactivity in 1898 and found the first radioactive elements and built the first field equipment to measure radioactivity
Because ALpha and Beta radiation are actual particles with mass.
Alpha radiation are effectively chiunks of Atomic nuclei being blasted off at extreme speeds(usually in the form os helium nucleus comprised of 2 protons and 2 neutrons)
Beta radiation are electrons at high speeds
Gamma radiation are high energy photons(a particle WITHOUT mass) at extremely high frequencies(meaning very high energy) which causes them to be highly penetrative.
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