What is the mole of 125 mg of Na? How many Na atoms?

(125 mg Na) x (1 g/1000mg) x (1 mol of Na/22.99 g) = 5.43 E -3 mols of Na

5.43 E -3 mols x 6.022 E 23 = 3.27 E 21 Na atoms

☆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