Isotopes When the Number of Neutrons Varies

Which of these pairs of ions have the same total number of electrons  

For a given element, the relative amounts of each different isotope in a naturally occurring sample of that element is always the same. For example, in any natural sample of neon atoms, 90.48% of them are the isotope with 10 neutrons, 0.27% are the isotope with 11 neutrons, and 9.25% are the isotope with 12 neutrons as summarized in Table 4.2. This means that out of 10,000 neon atoms, 9048 have 

There are a few exceptions to this ruie, such as boron, but they are beyond our scope in this text. 

Symbol Number of Protons Number of Neutrons A (Mass Number) Percent Natural Abundance 

Naturally occurring neon contains three different isotopes, Ne-20 (with 10 neutrons), Ne-21 (with 11 neutrons), and Ne-22 (with 12 neutrons). 

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