What’s so special about Lead that it’s used so extensively when working with radioactive substances?


Why can’t we use like a sheet of Gold or something

In: Chemistry

Lead is:

1. Very dense
2. Very cheap

Material density is pretty much the simplest way to make radiation shielding, and lead is very, very dense. While gold is denser than lead, gold is many thousands of times more expensive than lead, which can be had for a few dollars per kilo.

Lead is extremely dense, which makes it hard for a radioactive particle to thread a path through. It’s also very stable (it is the end product of many decay pathways) so incoming high energy particles are unlikely to light off another fission event and produce more trouble.

Now it’s not *the* densest metal around, but lining a reactor shield with gold or osmium is cost prohibitive.

Because a sheet of gold isn’t enough, you need like 5cm or more. And lead is cheap enough for us to use it in massive amounts. Concrete is also used by the way.

In addition to its density, a lead atom has a bunch of electrons (like 82), as opposed to something like steel (18 electrons). Someone smarter can probably better explain why that matters, but all those electrons disrupt the radiation.

Radiation is stopped by collisions with protons and elections. The denser a material, the more protons and electrons the radiation has to deal with. This is why denser materials are used as radiation shields. Beyond that, it’s a matter of cost. Lead is cheap and abundant on Earth. Gold is not.

Gold is very expensive and not as effective in stopping the radiation. So while lead is dangerous to your body it does a really good job. They can use gold in some situations where they want to avoid lead toxicity, but it’s not more useful most of the time.