<Tr> <Th> Ag </Th> <Td> syn </Td> <Td> 41.2 d </Td> <Td> ε </Td> <Td> Pd </Td> </Tr> <Tr> <Td> γ </Td> <Td>--</Td> </Tr> <Tr> <Th> Ag </Th> <Td> syn </Td> <Td> 8.28 d </Td> <Td> ε </Td> <Td> Pd </Td> </Tr> <Tr> <Td> γ </Td> <Td>--</Td> </Tr>

When was silver added to the periodic table