system
Given the following post, respond as if you're commenting on Reddit:
human
Is an atom of a particular element completely identical to every other atom of that element?

Also the same isotope of that element and bound to the same other molecules. For example are all the 12C carbons of all methane in the universe identical?  
EDIT: Isotope not isomer.
gpt
Yes, isotopes are essentially identical to other isotopes of the same type.

There will be some minor differences in the electron distribution, enhanced slightly by their different chemical environments, but other than that they are identical.

Edit. As mentioned below, electrons can be excited and ions can be formed after enough excitation.