There are two types of elements: Matter elements and Antimatter elements. In the 1860's, an alchemist named Dmitri Mendeleev captured and enslaved several matter elements, including Iron and Gold, keeping them in square prisons in his jailhouse, The Periodic Table. There was a great war about the freedom of these elements, but nobody cared, so nothing about it was ever recorded.
Dmitri Mendeleev was the first recorded example of an element-slave owner. He trapped and imprisoned wild elements in the Periodic table, starving them, and punishing them cruelly when they disobeyed him.
The Periodic Table
The main prison building was built in 1864. during its time as an element prison; The Table had been the site of a citadel since the 1860s. The Periodic Table was acquired by the United States Department of Justice on April 31, 1933, and the Table became a prison of the Federal Bureau of Prisons in August 1934 after the buildings were modernized to meet the requirements of a top-notch security prison. Given this high security, the prison operators believed the Table to be escape-proof and America's strongest prison.
The Table was designed to hold element-slaves. One of the world's most notorious and best known prisons over the years, the Table housed 118 of America's elements, including Aluminum, Strontium, Gold, and Beryllium. It also provided housing for the Bureau of Prisons staff and their families. It is still open to this date.