<Tr> <Td_colspan="2"> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) is also placed in this group in the periodic table, although no chemical experiments have yet been carried out to confirm that it behaves like the heavier homologue to gold . Group 11 is also known as the coinage metals, due to their former usage . They were most likely the first three elements discovered . Copper, silver, and gold all occur naturally in elemental form . </P> <P> All the elements of the group except roentgenium have been known since prehistoric times, as all of them occur in metallic form in nature and no extraction metallurgy is necessary to produce them . </P>

What does cu on the periodic table mean