Actinium is a soft, radioactive silvery-white metal at room temperature with a characteristic blue light glow. It is a chemical element with the atomic number 89 and is represented by the symbol Ac. Actinium is only found in small traces on the planet and it is only found in uranium ores. Even here it is very rare with a metric ton of uranium ore containing about 0.2 milligrams of this element! The naturally occurring isotope actinium-227 has a half life of 21.772 years, which is one of the reasons that this is such a rare element. Let’s find out who discovered actinium and when it was discovered.
Who discovered actinium?
There is some debate over the discovery of this element, but it is generally accepted that the French chemist André-Louis Debierne was the first to discover actinium in 1899. He separated the element from the residue of uraninite (a uranium ore), which was left over after scientists Marie and Pierre Curie had extracted radium. Debierne chose the name actinium and described the element as similar to titanium and thorium.
Actinium was also independently discovered by German chemist Friedrich Oskar Giesel in 1902. He thought this element was a new discovery and named the new element emanium because his observations were different to those of Debierne (Giesel thought it was similar to lanthanum). Later research had tried to suggest that Giesel was actually the first to discover the element. However, it is now accepted that Debierne’s substance did contain actinium and that he simply didn’t follow up his discovery with further investigations. Giesel was the first to prepare pure actinium and was also the first to identify its atomic number.
Did you know?
Even though this element was discovered independently by two chemists, the name chosen by Debierne became the official name for the element because he had discovered it first!