mods add one neutron to every atom in her body
#not to be a science nerd but i kinda wonder what would happen here#like presumably radioactive decay but what exactly would go down? would it kill you? fast or slow? much to think about
This would kill you in multiple ways.
If all your atoms gained one neutron, all the hydrogen in your body would become deuterium, so all the water in your body would become heavy water, which is very bad. In most cases, adding a neutron to an atom doesn't change its chemistry, but hydrogen is special because it's so light: chemical reactions involving deuterium and heavy water happen at different rates than those with regular hydrogen, and in living cells this messes with various enzymes, especially ones involving cell mitosis. Heavy water is fine to drink in small quantities, but once about 40% of your water is heavy water it becomes cytotoxic. 100% of your water being heavy water would certainly be fatal.
Let's go through the other atoms in your body and see what happens when we add a neutron:
Carbon: All your C-12 becomes C-13, but that's still stable. Your dead body would be incredibly confusing to future archaeologists trying to do radiocarbon dating though.
Nitrogen: N-14 becomes N-15, which is also stable. No problem.
Oxygen: O-15 becomes O-16. Still stable, not a problem.
Phosphorous: very bad. Your P-31 becomes P-32, which is a beta emitter with a short half-life of 2 weeks. Humans are about 1% phosphorus by mass, so you'd have something like 0.5-1.0 kilograms of a very hot isotope in you. Worse, since a lot of the phosphorous in your body literally makes up your DNA, the radioactivity would be right in the worst possible place. This would definitely be fatal.
Calcium: Ca-40 becomes Ca-41, which is radioactive, but has a half-life of 100,000 years. Not a big deal.
Sulfur: S-32 becomes S-33. Stable.
Sodium: also bad. Na-23 would become Na-24, which decays with both electron and gamma emission. I think the lower proportion of sodium in the body means the phosphorous is the bigger issue though.
Potassium: K-39 becomes K-40, which is another weakly radioactive one probably not worth worrying about.
My guess is that the phosphorous-induced radiation damage would kill you long before the heavy water cytotoxicity did. Since it's right in your DNA, you'd probably stop synthesizing proteins almost immediately and have an unpleasant death similar to amanita mushroom poisoning (which inhibits RNA polymerase), which typically takes less than a day.
