Et
In short
Et is the chemical symbol for the element Astatine, though it is more commonly represented by the symbol At in scientific contexts.
In plain words
It is a very rare and unstable chemical element. It is so radioactive that it disappears almost as soon as it is created.
A simple example
If you were to gather a visible amount of this substance, it would instantly vanish due to its intense heat and radiation.
Why it matters
Studying it helps scientists understand how heavy elements behave and how they are formed in stars. It is a key part of nuclear physics research.
Easy to mix up
It is often confused with the symbol At, which is the correct standard notation for Astatine.