Definition: Relative amounts of each isotope of
an element found in nature, expressed as percentages.
Example 1: Carbon
Carbon-12 (⁶C¹²): ~98.9%
Carbon-13 (⁶C¹³): ~1.1%
Example 2: Hydrogen
Protium (¹H¹): ~99.98%
Deuterium (¹H²): ~0.02%
Tritium (¹H³): Trace amounts
The Origin of Elements
Click to watch the video
Factors Controlling Natural Abundance of Isotopes
Nuclear Stability: Stable isotopes are more
abundant.
Production Mechanisms: the production mechanisms
influence isotopes relative abundances in nature (i.e., Stellar
Production, Lighter isotopes are often more abundant than heavier
isotopes).
Decay Rates: Isotopes with shorter half-lives decay
faster and they are less aboundance in nature.
Cosmic and Geological Processes: Alterations from
events and processes make some isotopes less aboundace compare to
others..
Chemical and Physical Processes: Isotopic
fractionation affacts the abundance of isotopes.
Atomic Number: Affects stability and abundance;
higher atomic numbers often lead to more radioactive isotopes.
Atomic number vs abundances of the elements
Abundances of the elements as a function of atomic number, (Source: Lodders, K.
(2010))
Nuclear Stability
Binding Energy: Energy required to hold nucleons
together, higher binding energies increase stability.
Neutron-to-Proton Ratio: Balance between protons
and neutrons affects stability.
Magic Numbers: 2, 8, 20, 28, 50, 82, and 126.
Example: impact of Neutron-to-Proton Ratio on the abundance
Natural Abundance of Carbon Isotopes with Neutron-Proton Balance
