 In 1971, Fricke calculated the periodic table up to "Z" = 172, and discovered that some elements indeed had different properties that break the established pattern, and a 2010 calculation by Pekka Pyykkö also noted that several elements might behave differently than expected.It is unknown how far the periodic table might extend beyond the known 118 elements, as heavier elements are predicted to be increasingly unstable.Glenn T. Seaborg suggested that the highest possible element may be under "Z" = 130, while Walter Greiner predicted that there may not be a highest possible element.