The mineral monazite consists of phosphates of several of these elements.
The mineral monazite consists of phosphates of several of these elements. A mixture of these elements called misch metal is used to purify steel, and an alloy of one of these elements with cobalt produces the strongest known permanent magnetic force. A slightly larger group consists of these elements as well as scandium and yttrium, the rare earth metals, and cerium is the most abundant of these elements in nature. Their namesake contraction, or unexpected decrease in ionic radius, is due the poor shielding of 4f electrons. Including samarium and gadolinium, for 10 points, name these metals of atomic numbers 57 through 71, grouped just above the actinides on the periodic table.
The mineral monazite consists of phosphates of several of these elements.
{lanthanide series} or {lanthanides}