The illustration below shows the three isotopes of carbon.
Some isotopes of certain elements are unstable; they can spontaneously change into another kind of atom in a process called “radioactive decay.” Since this process presently happens at a known measured rate, scientists attempt to use it like a “clock” to tell how long ago a rock or fossil formed.
Assumptions in the scientific community are extremely important.
If the starting assumption is false, all the calculations based on that assumption might be correct but still give a wrong conclusion. Libby’s original work, he noted that the atmosphere did not appear to be in equilibrium. Libby since he believed the world was billions of years old and enough time had passed to achieve equilibrium. Libby’s calculations showed that if the earth started with no If the cosmic radiation has remained at its present intensity for 20,000 or 30,000 years, and if the carbon reservoir has not changed appreciably in this time, then there exists at the present time a complete balance between the rate of disintegration of radiocarbon atoms and the rate of assimilation of new radiocarbon atoms for all material in the life-cycle.2C in the atmosphere.
For example, all carbon atoms have 6 protons, all atoms of nitrogen have 7 protons, and all oxygen atoms have 8 protons.
The number of neutrons in the nucleus can vary in any given type of atom.
Recall that atoms are the basic building blocks of matter.