Period 5 element electrical contacts and the production of thick-film resistors. A minor application of ruthenium is its use in some platinum alloys. Rhodium is a chemical element that is a rare, silvery-white, hard, and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope,Rh. Naturally occurring rhodium is found as the free metal, alloyed with similar metals, and never as a chemical compound. It is one of the rarest precious metals and one of the most costly (gold has since taken over the top
Interstitial element Interstitial element An interstitial element is an impurity found in "pure" metals or crystals. The quantity of these elements affect the physical properties of the host material. They can be introduced during the manufacturing process. The most common interstitial elements in metals are hydrogen, carbon, nitrogen, and oxygen. These elements are small enough to fit between normal crystalline lattice locations. In contrast, those elements that replace locations in the crystalline structure are called substitutional elements. An example of the effects of interstitial elements on metal properties can be found in grade 1–4 titanium. Although the grades 1–4 are considered commercially