Please help!! Hydrogen has two stable isotopes, 1^H and 2^H, Find the Average Atomic Mass relaizing that 1H has an
abundance of 98.5%.

☆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