Iggy's Element Bonanza! Element: Yttrium Atomic Symbol: Y Atomic Number: 39 Iggy: Yttrium is a transition metal that chemically similar to the lanthanides and is never found as a free element. It is a silvery white metal that can form various compounds with other elements. Yttrium is monoisotopic with one stable isotope, Y-89 and the most stable radioisotope is Y-88 with a half-life of 106.6 days.