The Beechmont Crest Online Guide to Organic Chemistry
ATOMIC NUMBER AND ISOTOPES
Isotopes are elements that have the same atomic number but different mass numbers.
Since isotopes have the same atomic number, they have the same number of protons. However, they have different numbers of neutrons, so the sums of the protons and neutrons in their nuclei are also different.
Carbon has three naturally occurring isotopes. The isotopes of carbon are carbon-12, carbon-13, and carbon-14.
Carbon-12 constitutes 98.89 of all carbon atoms. It serves as the standard for the atomic mass scale.
Carbon-13 is the only magnetic isotope. It is essential for structural studies of compounds that contain carbon.
Carbon-14 is radioactive; it has a half-life of 5760 years. Scientists measure the amount of carbon-14 remaining in historical relics and fossils to estimate their age.
