why group 2 elements called alkaline earth metals
Alkaline earth metal The alkaline earth metals are named after their oxides, the alkaline earths, whose old-fashioned names were beryllia, magnesia, lime, strontia, and baryta. These oxides are basic (alkaline) when combined with water. "Earth" is an old term applied by early chemists to nonmetallic substances that are insoluble in water and resistant to heating—properties shared by these oxides. The realization that these earths were not elements but compounds is attributed to the chemist Antoine Lavoisier. In his Traité Élémentaire de Chimie (Elements of Chemistry) of 1789 he called them salt-forming earth elements. Later, he suggested that the alkaline earths might be metal oxides, but admitted that this was mere conjecture. In 1808, acting on Lavoisier's idea, Humphry Davy became the first to obtain samples of the metals by electrolysis of their molten earths,[24] thus supporting Lavoisier's hypothesis and causing the group to be named the alkaline earth metals.
Rare-earth element A rare-earth element (REE) or rare-earth metal (REM), as defined by IUPAC, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium.[2] Scandium and yttrium are considered rare-earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties. For the same set of mineralogical, chemical, physical (especially electron shell configuration), and related reasons, a broader definition of rare earth elements including the actinides is encountered in some cases. Thorium is a significant component of monazite and other important rare earth minerals, and uranium and decay products are found in others.[3] Both series of elements begin on the periodic table in group 3 under yttrium and scandium.