Symbol

Re

Atomic Number

75

Atomic Mass

186.207

Family

Group 7 (Viib) Transition Metal Pronunciation

REE-nee-um

Overview

Rhenium was discovered by a German research team that included Walter Noddack (1893-1960), Ida Tacke (1896-1979) and Otto Berg. These scientists knew that there were two empty boxes in the periodic table that represented elements that had not yet been discovered. The periodic table is a chart that shows how chemical elements are related to one another. In 1925, the German team announced that they had found both elements. They were correct about one (element number 75) but wrong about the other (element number 43).

Rhenium is one of the rarest elements in the world. At one time it sold for about $10,000,000 a kilogram (about $5,000,000 a pound). It is no longer that expensive, although it is still very costly.

Rhenium has some unusual properties. For example, it is one of the most dense elements known. It also...