# What are atoms with the same number of protons but different number of of neutrons called?

$\text{Isotopes}$
For the isotopes of hydrogen see this answer. Most elements possess several isotopes, some of which may be especially useful for spectroscopic analysis. The use of ""^13C in NMR spectroscopy, and ""^13C is an isotope that has an abundance of only 1%, is now widespread and routine in organic chemistry.