What Are the Radioactive Elements? 1

Periodic Table of Radioactive Elements

This is a list of the radioactive elements of the periodic table. While all elements have some radioactive isotopes, these 37 elements have no stable isotopes. These elements are considered the “radioactive elements”.

The periodic table above is a visual representation of the data in the table below. It is available to download as an image or black and white PDF.

Table of Radioactive Elements

This is a list of the radioactive elements and their most stable isotopes. While many of these elements have half-lives so long they almost appear stable, the heavier elements decay almost instantly.

ElementMost Stable
Half-life of Most
Stable Isotope
TechnetiumTc-914.21 x 106 years
PromethiumPm-14517.4 years
PoloniumPo-209102 years
AstatineAt-2108.1 hours
RadonRn-2223.82 days
FranciumFr-22322 minutes
RadiumRa-2261600 years
ActiniumAc-22721.77 years
ThoriumTh-2297.54 x 104 years
ProtactiniumPa-2313.28 x 104 years
UraniumU-2362.34 x 107 years
NeptuniumNp-2372.14 x 106 years
PlutoniumPu-2448.00 x 107 years
AmericiumAm-2437370 years
CuriumCm-2471.56 x 107 years
BerkeliumBk-2471380 years
CaliforniumCf-251898 years
EinsteiniumEs-252471.7 days
FermiumFm-257100.5 days
MendeleviumMd-25851.5 days
NobeliumNo-25958 minutes
LawrenciumLr-2624 hours
RutherfordiumRf-26513 hours
DubniumDb-26832 hours
SeaborgiumSg-2712.4 minutes
BohriumBh-26717 seconds
HassiumHs-2699.7 seconds
MeitneriumMt-2760.72 seconds
DarmstadtiumDs-28111.1 seconds
RoentgeniumRg-28126 seconds
CoperniciumCn-28529 seconds
NihoniumNh-2840.48 seconds
FleroviumFl-2892.65 seconds
MoscoviumMc-28987 milliseconds
LivermoriumLv-29361 milliseconds
OganessonOg-2941.8 milliseconds

One thought on “What Are the Radioactive Elements?

  • Anne Helmenstine

    Good question! The short answer is the mass of the proton and neutron is not exactly the same, so there is no number of each that produces a stable nucleus. I’ll write up the full explanation in an article.

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