Can someone summarize the concept of chemical bonding and counting atoms in an equation?

You need to have 8 electrons to fill an atom and to fill bond the pairs need to equal 8

Man i dont know this answer

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts