To determine which isotope of an element is the most common, you can look at the element’s atomic mass listed on the periodic table. The atomic mass is a weighted average of all the isotopes of that element, taking into account their relative abundances. Isotopes are atoms of the same element that have different numbers of neutrons, resulting in different mass numbers.
For example, carbon has two stable isotopes: carbon-12 and carbon-13. Most naturally occurring carbon is carbon-12, which has an atomic mass close to 12, while carbon-13 is much less abundant. By examining the atomic mass of carbon (approximately 12.01), you can infer that carbon-12 is the most common isotope.
In practice, scientists use mass spectrometry or other techniques to measure the relative abundances of isotopes in a sample. The most abundant isotope will have a peak with the highest intensity in the mass spectrum. Thus, evaluating atomic mass and utilizing analytical techniques are effective ways to identify the most common isotope of an element.