Which is the lightest radioactive element?

Answer 1

The lightest radioactive element is tritium, 3H, an isotope of hydrogen. It's hydrogen with its one proton, but it has two neutrons hanging around in its nucleus as well. Tritium, 3H, is created naturally by cosmic rays. It has a half-life of 12.32 years, at which time it undergoes decay to 3He. It is also the product of neutron activation or neutron capture in nuclear reactors. Wikipedia has an article with more information, and a link is provided.
The lightest radioactive element is the hydrogen isotope "tritium". All hydrogen atoms have one proton. A tiny percentage of hydrogen atoms are "heavy hydrogen", called deuterium, which has one proton and one neutron.

Tritium is "extra-heavy hydrogen", having one one proton and TWO neutrons. Tritium has a fairly short half-life and decays into helium-3.

Answer 2

Yes, but don't run off 'til you get the full picture. Isotopes are different "versions" of a given element that have differing numbers of neutrons in the nucleus. As a quick for instance, we're familiar with uranium, and it has two "popular" isotopes - 238U and 235U. The former is the most common, and the latter is the highly desireable, by scarce, fissile isotope. The difference in the two is that the former has 3 more neutrons in the nucleus than the latter. That's just one example of an element and a couple of its isotopes. Now that you're down with that, let's consider what different isotopes are possible for the elements. It turns out that some isotopes of elements are unstable and some are not. Also, all elements from bismuth and up have no stable nuclear structures. With that covered, we need to know what the physicists have been doing in the nuclear physics labs. What they've been doing (among other things) is creating different isotopes of different elements to see what is possible. And there are a lot of possibilities. A lot of them. We can make other isotopes of elements that have greater or have fewer numbers of neutrons than the stable ones in every case (except hydrogen and helium). And in all those cases, we can make a radioisotope that is lighter than any stable isotope of an element. That means that in every case (except hydrogen and helium), a radioisotope, that is, a radioactive or an unstable isotope, is the lightest isotope of the element know to physics. There is a chart "similar" to the Periodic Table of elements that is called the table of nuclides that sets out particulars. This bad boy can get pretty big, but a link is provided to one that is interactive. It was posted by our friends at the Brookhaven National Laboratory under the auspices of the National Nuclear Data Center, and all so we'd have a reference to look up related information. That link to the table of nuclides is below.

Answer 3

Radium , discovered by Marie Curie , is the lightest man -made radioactive element , with a Atomic Mass of 226