<Table> <Tr> <Td> Primordial </Td> <Td> </Td> <Td> From decay </Td> <Td> </Td> <Td> Synthetic </Td> <Td> Border shows natural occurrence of the element </Td> </Tr> </Table> <Tr> <Td> Primordial </Td> <Td> </Td> <Td> From decay </Td> <Td> </Td> <Td> Synthetic </Td> <Td> Border shows natural occurrence of the element </Td> </Tr> <Tr> <Td> <Table> <Tr> <Td_colspan="11"> Background color shows subcategory in the metal--metalloid--nonmetal trend: </Td> </Tr> <Tr> <Td_colspan="6"> Metal </Td> <Td> Metalloid </Td> <Td_colspan="3"> Nonmetal </Td> <Td> Unknown chemical properties </Td> </Tr> <Tr> <Td> Alkali metal </Td> <Td> Alkaline earth metal </Td> <Td> Lanthanide </Td> <Td> Actinide </Td> <Td> Transition metal </Td> <Td> Post - ​ transition metal </Td> <Td> Polyatomic nonmetal </Td> <Td> Diatomic nonmetal </Td> <Td> Noble gas </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td_colspan="11"> Background color shows subcategory in the metal--metalloid--nonmetal trend: </Td> </Tr> <Tr> <Td_colspan="6"> Metal </Td> <Td> Metalloid </Td> <Td_colspan="3"> Nonmetal </Td> <Td> Unknown chemical properties </Td> </Tr> <Tr> <Td> Alkali metal </Td> <Td> Alkaline earth metal </Td> <Td> Lanthanide </Td> <Td> Actinide </Td> <Td> Transition metal </Td> <Td> Post - ​ transition metal </Td> <Td> Polyatomic nonmetal </Td> <Td> Diatomic nonmetal </Td> <Td> Noble gas </Td> </Tr> </Table>

What does a highly negative electron affinity mean