Beryllium is a metallic chemical element grouped with the alkaline earth elements, which include magnesium, calcium, barium, radium, and strontium. Like other elements in this group, beryllium is a silvery gray metal, and its oxides are alkaline. There are a number of uses for beryllium, although care needs to be taken when handling it, since it has been established as a carcinogen. People who are exposed to beryllium on a regular basis should be especially careful about lung protection, as inhaling the fumes and particles of beryllium is very hazardous for lung health.

The atomic number of beryllium is four, and it is indicated by the symbol Be on the periodic table of elements. It is the lightest of the alkaline earth elements, and appears in a rigid, steely gray form when it is pure. The element is able to resist corrosion rather well, and it also has a very high melting point. This traits make beryllium a popular inclusion in metal alloys. The hexagonal crystalline structure of beryllium makes it rather elastic, and the metal also has excellent thermal and electrical conductivity.

Pure beryllium is not found in nature, and it was not isolated until 1828. One of the more well known beryllium compounds is beryl, called aquamarine or emerald when it appears in a gem form. It also appears in bertrandite and phenakite, among other compounds. Widespread isolation of beryllium for industrial use did not begin until the 1950s, and it continues to be an expensive and difficult process. As a result, pure beryllium commands a high price.

Initially, beryllium was known as glucinium, because the salts of the element are naturally sweet. Fortunately, scientists do not need to taste these salts to identify them any longer, as they carcinogenic. Among its many uses, beryllium is alloyed with copper and employed in nuclear reactors. It is also used for x-ray diagnostics, and it appears in some aerospace manufacturing, since the element is lightweight, strong, and flexible, especially when alloyed.

Exposure to beryllium can result in the formation of systemic granulomas, especially in the respiratory tract. Long term exposure is closely linked with lung cancer. Chronic beryllium disease, the result of abnormally high levels of exposure, can appear years after the exposure, and is characterized by difficulty breathing, exhaustion, heart disease, and severe weight loss. Some people also experience skin problems such as rashes as a result of beryllium exposure.