I’ve been searching and can’t quite find the explanation I’m looking for. I’ve read that radioactivity comes from an atom containing too many neutrons, and so the neutrons will end up breaking off of the atom and go flying in some direction until it collides with something. Which leads me to my first part:
* What happens when this neutron collides with something?
* If we’re talking a person, I’m assuming it damages/destroys the cell it hits, does it bounce and keep destroying more? What if a person was exposed to insanely high radiation of this sort. Do they melt into a pile of goop as their cells are broken down?
I’ve read that the number after an element is supposed to represent the amount of neutrons. So Uranium-238 would have more neutrons than Uranium-235. But isn’t the protons/neutron/electron the entire makeup of the atom?
* How can the amount of neutrons differ and they still be considered the same element?
From what I understand, radioactive decay is what happens to a radioactive element naturally as it’s neutrons fire off.
* What happens to the element? Does it just eventually disappear or “evaporate”? What exactly happens to these atoms once the neutrons have all fired off?
* If the radioactive substance is a metal such as iridium, does it become super brittle once fully decayed? Crumble into dust?
I have absolutely no education or experience in this field, but it fascinates the hell out of me.
In: Chemistry
Initial clarification: it’s not necessarily too many neutrons, it’s the wrong number of neutrons. Once you go past hydrogen (1 proton), you need at least one neutron to get the nucleus to be stable(ish). “Stable” means “does not radioactively decay into something else.” Decay can happen by turning a proton into a neutron by ejecting a positron (beta+ decay), by turning a neutron into a proton by ejecting an electron (beta- decay), by rejecting a pair of protons and neutrons entirely (a helium nucleus, alpha decay), or by splitting entirely and possibly spewing out some free neutrons and/or gamma rays and/or heat (fission).
If any of this happens with enough energy, the particles coming out can hit other atoms hard enough to rip electrons off them. This is called “ionizing radiation”. And ions like to undergo chemical reactions, including bonding to other things or breaking existing bonds. This can screw up chemistry in cells and, in particular, damage DNA. If you do enough of that you get cancer. Even more of that and you physically damage the cells enough to kill them (radiation poisoning). Even more of that and you can just burn a person up because they’re absorbing too much energy.
The number after some elements isn’t the number of neutrons, it’s the total number of protons+neutrons in the nucleus. U-238 has 92 protons and 238-92=146 neutrons. When it changes to U-235 it’s still got 92 protons but it lost 3 neutrons. The number of protons is what makes it uranium…uranium always has 92 protons. If the number of protons changes it’s a different element. But if *just* the number of neutrons changes it’s a different “isotope”…chemically the same, since the electrons are what makes chemistry happen and they balance the protons, but different numbers of neutrons so it weights slightly more or less. And, since the neutrons influence stability, different isotopes have different stability.
If an element just loses a neutron, it changes isotopes. It will keep doing that until it hits a stable isotope or some other kind of decay happens to change the number of protons (alpha, beta, or fission will all change the proton count). If that happens it becomes a new element or elements (fission), called “transmutation”. Which may or may not be stable. This keeps going on until everything that’s left is stable or the age of the universe runs out, whichever happens first.
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