Why is it important to know about electron shell of an atom? What does it tell you about the atom?

In general, atoms are most stable, least reactive, when their outermost electron shell is full. Most of the elements important in biology need eight electrons in their outermost shell in order to be stable, and this rule of thumb is known as the octet rule.

This atomic number tells you the number of protons and electrons in an atom. ... The atomic mass tells us the weight of protons and neutrons.

Explanation:

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