Question

The oxidation state shown by an element of the second period is -2
a. How many electrons are there in the outer most shell of this element?
b. Write down the subshell electronic configuration of the element.​

Answer 1

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.

Answer 2

Oxygen oxidation  state is -2

(a) 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.

(b) For example, if two electrons are filled in the 's' subshell of the first shell, the resulting notation is '1s2'. With the help of these subshell labels, the electron configuration of magnesium (atomic number 12) can be written as 1s2 2s2 2p6 3s2.