Palladium Palladium Palladium is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. More than half the supply of palladium
Element (UML) Element (UML) In the Unified Modeling Language (UML), an Element is an abstract class with no superclass. It is used as the superclass or base class, as known by object oriented programmers, for all the metaclasses in the UML infrastructure library. All other elements in the UML inherit, directly or indirectly from Element. An Element has a derived composition association to itself to support the general capability for elements to own other elements. As such, it has no additional attributes as part of its specification. An association describes a set of tuples of typed instances. The Element class belongs to