In the Periodic Table; why are there only 2 elements in period 1 but there are 8 elements in period 2 ?

read below!^^

Explanation:

“There are 8 elements in period 2 because all those elements have electrons in the second shell and no electrons in the third shell.”

also: “The 1st period has two elements because the 1st electron shell of an atom can take a maximum of two electrons only. The 2nd period of the periodic table has 8 electrons because the maximum no. of electrons which can be put in the 2nd shell of an atom is 8.”

articles I used:

1) https://chemistry.stackexchange.com/questions/44640/in-the-periodic-table-why-doesnt-the-2nd-row-have-exactly-2-elements

2) https://www.studyrankersonline.com/83833/explain-first-period-modern-periodic-table-elements-whereas-second-period-eight-elements

Hope these help!

have a lovely day/night!

b) phosphorus pentoxide