Lanthanide — ল্যান্থানাইড
Lanthanides are the 15 rare-earth metals from lanthanum (Z 57) to lutetium (Z 71), shown as a detached row.
Definition
The lanthanides are the 15 elements from lanthanum to lutetium, atomic numbers 57 to 71, whose 4f subshell is filling. They are silvery, fairly reactive metals, so alike in size and behaviour that separating them is genuinely difficult chemistry — they hide together in the same ores. With scandium and yttrium they form the rare earths, a misleading name, since cerium is about as common as copper. Neodymium's magnets make your earbuds sing; lanthanum glass sharpens camera lenses; europium and terbium put colour into screens.
For example
Pop open a pair of earbuds and you will find neodymium magnets small enough to hide under a fingernail yet strong enough to pinch your skin — lanthanide chemistry in your pocket.