An electron in the n=7 level of the hydrogen atom relaxes to a lower energy level, emitting light of 2166 nm

1) how many electrons are in each energy level of the following elements? a. he b. na c. na d. ne 2) how many valence electrons are percent in the following atoms? a. s b. mg c. be d. cl 3) which of the following elements are stable as atoms? a. he b. o c. cl d. ar if you are able to provide the work as to how you got the answers that would be greatly appreciated. : )

This is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table.

May someone me with these science questions