How many electrons does an atom need in its outer shell in order to be stable?

eight electrons

Explanation:

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. Some atoms can be stable with an octet even though their balance she'll is the 3n shell, which can hold up to 18 electrons.

2b2t

explanation:

2b2t

b) nuclear ive learned that in a pedtrodic table