(Encyclopedia) earth, in chemistry, metallic oxide not readily reducible by chemical means, e.g., alkaline earths, rare earths, and alumina. The name is also applied to certain absorbent clays, e.g…
(Encyclopedia) rare-earth metals, in chemistry, group of metals including those of the lanthanide series and actinide series and usually yttrium, sometimes scandium and thorium, and rarely zirconium…
April 22, 2017, marks the 47th anniversary of Earth Day—a day intended to inspire awareness and appreciation for the Earth's natural environment. Organizers started Earth Day in response to a…
Middle-earth Timeline From the creation of Middle-earth to the War of the Ring by Laura Hayes Tolkien created a long and rich history for Middle-earth, and meant it to be an…
(Encyclopedia) alkaline-earth metals, metals constituting Group 2 of the periodic table. Generally, they are softer than most other metals, react readily with water (especially when heated), and are…
