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
Period 4 element only major application is in aluminium alloys. Titanium (Ti) is an element in period 4, between scandium and vanadium. Titanium is both one of the least dense metals and one of the strongest and most corrosion-resistant, and as such has many applications, especially in alloys with other elements, such as iron. Due to its aforementioned properties, it is commonly used in airplanes, golf clubs, and other objects that must be strong, but lightweight. Vanadium (V) is an element in period 4, between titanium and chromium. Vanadium is never found in pure form in nature, but is commonly found in compounds.