Isotopes participate in the same chemical reactions but often at differing rates.
When isotopes are to be designated specifically, the chemical symbol is expanded to identify the mass (for example, C is not stable.
Archaeologists call this kind of behavior "curation" -- people then, just like today, like to hang on to old things.
Ninety-nine percent of these also contain six neutrons.
The 6 proton 6 neutron atoms are said to have a mass of 12 and are referred to as "carbon-12." The nuclei of the remaining one percent of carbon atoms contain not six but either seven or eight neutrons in addition to the standard six protons.
Signals of this kind are often used by chemists studying natural environments.
A hydrocarbon found in beach sediments, for example, might derive from an oil spill or from waxes produced by plants.
One early recording method consisted of large plastic disks which could only be played on a huge device called a gramophone.