<Tr> <Td> 93 </Td> <Td> Np </Td> <Td> Neptunium </Td> <Td> Neptune, the eighth planet in the Solar System </Td> <Td> </Td> <Td> 7 </Td> <Td> 237! (237) </Td> <Td> 20.45 </Td> <Td> 0917! 917 </Td> <Td> 4273 </Td> <Td>--</Td> <Td> 1.36 </Td> <Td> 0.000000000003! ≤ 3 × 10 </Td> </Tr> <Tr> <Td> 94 </Td> <Td> Pu </Td> <Td> Plutonium </Td> <Td> Pluto, a dwarf planet in the Solar System (then considered the ninth planet) </Td> <Td> </Td> <Td> 7 </Td> <Td> 244! (244) </Td> <Td> 19.84 </Td> <Td> 0912.5! 912.5 </Td> <Td> 3501 </Td> <Td>--</Td> <Td> 1.28 </Td> <Td> 0.00000000003! ≤ 3 × 10 </Td> </Tr> <Tr> <Td> 95 </Td> <Td> Am </Td> <Td> Americium </Td> <Td> The Americas, as the element was first synthesized on the continent, by analogy with europium </Td> <Td> </Td> <Td> 7 </Td> <Td> 243! (243) </Td> <Td> 13.69 </Td> <Td> 1449 </Td> <Td> 2880 </Td> <Td>--</Td> <Td> 1.13 </Td> <Td> 0! 0 </Td> </Tr> <Tr> <Td> 96 </Td> <Td> Cm </Td> <Td> Curium </Td> <Td> Pierre Curie, a physicist, and Marie Curie, a physicist and chemist, named after great scientists by analogy with gadolinium </Td> <Td> </Td> <Td> 7 </Td> <Td> 247! (247) </Td> <Td> 13.51 </Td> <Td> 1613 </Td> <Td> 3383 </Td> <Td>--</Td> <Td> 1.28 </Td> <Td> 0! 0 </Td> </Tr>

Where is the majority of an atoms mass found