Which is the heaviest element in the Universe?

8 Answers

caledon's profile pic

caledon | High School Teacher | (Level 3) Senior Educator

Posted on

The heaviest element that we have actually observed is ununoctium, with an atomic mass of 294. Only a few atoms of this element have been synthesized as of 2014.

Hypothetically speaking, it should be possible to continue creating heavier and heavier elements, although they are likely to be extremely unstable. The forces of electromagnetism and the strong and weak nuclear forces would determine the upper limit of an atom's mass under a given set of circumstances. Currently there is no set limit to how big it is possible for an atom to get, although atoms like ununoctium only exist for fractions of a second before they decay; thus the "existence" of such an atom is arguable depending on whether you're talking about the atomic scale or the everyday human scale.

While uranium is commonly cited as the heaviest "naturally" occurring element, there are transuranium elements found in nature as well, although some of them have such short half-lives that they no longer exist. For example, trace amounts of plutonium, with mass 244, have been found in ore samples.

pacorz's profile pic

pacorz | High School Teacher | (Level 3) Educator

Posted on

Well, the answer to this question is a little more complicated than you may have anticipated. If we only consider the natural elements, then the answer is uranium, element number 92. Uranium occurs naturally as several different isotopes, the heaviest of which is Uranium-238.

However, Uranium-238 is not the heaviest element if you take into account all the man-made elements that have been created. At this moment we are up to element 118, ununoctium, which has an atomic weight of 294. But as scientists continue to create and document larger elements, the answer to your question will continue to change.