Low-coordinate complexes of the monovalent type of this metal aggregate into polymers through an unusual form of bonding explained by relativistic effects. In an electron microscopy staining technique, secondary antibodies attach to colloidal particles of this element. The most common process for extracting this metal adds 
Low-coordinate complexes of the monovalent type of this metal aggregate into polymers through an unusual form of bonding explained by relativistic effects. In an electron microscopy staining technique, secondary antibodies attach to colloidal particles of this element. The most common process for extracting this metal adds an excess of cyanide ion is to form a coordination complex. Salts of this element are commonly used to treat rheumatoid arthritis. This neutral element has an electronic configuration oddly ending in (*) 5d10 6s1. This is the heaviest element that can be dissolved by a mixture of concentrated nitric and hydrochloric acid known as aqua regia. For 10 points, name this valuable transition metal whose purest alloys clock in at 24 carats.
Low-coordinate complexes of the monovalent type of this metal aggregate into polymers through an unusual form of bonding explained by relativistic effects.
gold [or Au]