Studying the Periodic Table and noted that Cobalt, element 27 has an atomic weight of 58.93320 AND IS HEAVIER THAN Nickel which is element 28 which has an atomic weight of 58.6934
Cobalt is 2,8,15,2 while nickel is 2,8,16,2
How can a nucleus and 27 electrons and protons weigh more than a nucleus and 28 electrons and protons ?
Could someone explain to me how cobalt can be heavier than nickel ?
Thanks in advance