Charring Auh<p><a href="https://mastodon.social/tags/Technetium" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Technetium</span></a> is a chemical element; it has symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. Technetium and promethium are the only radioactive elements whose neighbours in the sense of atomic number are both stable. All available technetium is produced as a synthetic element.</p>