Brian Livingston, age 12, of Washington, Illinois, for his question:
What are cerium, lanthanum and neodymium?
First, they are not a triplet of elves left over from Christmas. Their names might sug¬gest something of this sort. But a young science student could not be fooled. He sees at a glance that the word endings suggest that the triplet of odd names may belong to three chemical elements.
These atomic elements were not charted on the Periodic Table drafted by Mendeleev in the 19th century. In the 1870's, the great chemist predicted'the discovery of more elements, described them and left empty slots to add them in their proper places. But he could not predict our atomic family of rare or inert. gases. Nor did he provide a line of slots for cerium, lanthanum and neodymium, though two of them already had been discovered. The up ¬to date Periodic Table of the basic chemical elements lists them with a dozen other elements in a family of their own.
Most of the other basic elements are charted in rows and lines with interlocking rela¬tionships across and up and down. Our fancy friends seem to be an atomic breed apart. They are charted in a separate line from the main table, either in a row at the bottom or stacked in a separate deck along one side. These strange 15 elements are called the lanthanides because they resemble the element lanthanum.
When they were discovered in the last century, it was hard to separate them from each other and from their oxide compounds. The elements themsleves seemed to be as scarce as hen's teeth and the materials on hand suggested earthy limes. So the elements in the strange family were called "rare earths." Their family resemblances are stronger than those in other atomic families and the so called rare earths usually occur together in the same mineral ores. Not until late in the 1950's did scientists discover how to pull them apart.
They did not rate with the commonest elements of our world, but most of the lanthanides have proved far from rare. Cerium, the most abundant, is as plentiful as beryllium and molybdenum and none is as rare as radium. In pure form, the lanthanides are cheesy soft , metals of silvery grays. The so called rare earths are not rare and are unlike other earthy minerals.
The atoms of all 15 elements have an outer shell of two electrons and the next shell contains either eight or none. These similarities dictate similar chemical reactions. Many lanthanides are used to add fine texture and pliable qualities to alloys of iron and ¬cerium, lanthanum and neodymium for Saturday, 3anpary 6, 1968 steel. Cerium also adds heat resistance and its alloys are used to make parts for jet engines. Both lanthanum and neodymium play tricks with light and glass. There may be traces of lanthanum in a super fine camera lens. A trace of pure neodymium creates a vivid glass of rich purple. Less pure neodymium is added to glass recipes to clear out murky tinges.
As a rule, all 15 lanthanides occur in the same mineral ores. They were extracted, but not separated, early in the century. The mixture was and still is known as "misch metal." It is combined with iron to make lighter flints and a trace of the mixture purifies and improves iron alloys. A pound of misch metal costs about $3.15. When separated the lanthanides are more costly. Scientists are still probing the nature of lutetium and at present nobody has a use for it. But this mysterious lanthanide sells for $1,300.00 per pound.