He
discovered some rare-earth elements.
He
had a daughter who went on to be the first woman in Sweden to earn a
doctoral degree in the sciences.
And
he had a grandson who earned a Nobel Prize in Physiology!
Per
Teodor Cleve was a Swedish chemist and geologist who was born on this
date in 1840. As he studied rocks and minerals, he tried to figure
out what elements made them up.
An
earlier scientist, Carl Mosander, had discovered that a mineral
called cerite was made up of the elements cerium, lanthanum, and
didymium. The latter two elements were Mosander's discoveries, and so
he got to name them. Lanthanum and didymium were entered into the
Periodic Table of Elements of the day, and given appropriate
abbreviations (La and Di). But...it turned out that Mosander was
wrong about didymium being an element.
Cleve
was able to prove that didymium could be broken down into two
different elements. Later scientists were able to separate the salts
of the two new elements, which are named neodymium (“new” dymium)
and praseodymium (“green” dymium).
 |
| Neodymium |
 |
| Praseodymium |
This
is not an embarrassing chapter of science! This story does not prove
that Mosander was a careless or ignorant scientist! He did the best
he could with the equipment he had, and he made many discoveries that
still stand today, including three elements. Instead of being an
embarrassing chapter of science, this is a great story—it shows,
once again, that science is self-correcting, that later discoveries
often refine older discoveries, and that scientists are able to reach
new heights of understanding partly because they are figuratively
standing on the shoulders of great scientists of the past!
Our
birthday boy, Cleve, also discovered two more new rare-earth
elements: holmium and thulium.
Also
on this date:
