Question

What is the average atomic mass of all of the naturally occurring isotopes of nickel in amu?

Answer 1

In general chemistry, isotopes are substances that belong to one specific element. So, they all have the same atomic numbers. But they only differ in the mass numbers, or the number of protons and neutrons in the nucleus. In a nutshell, they only differ in the number of neutrons.

For Nickel, there are 5 naturally occurring isotopes. Their identities, masses and relative abundance are listed below

  Isotope                Abundance           Atomic Mass
   Ni-58                    68.0769%              57.9353 amu
   Ni-60                    26.2231%              59.9308 amu
   Ni-61                    1.1399 %               60.9311 amu
   Ni-62                    3.6345%                61.9283 amu
   Ni-64                    0.9256%                63.9280 amu

To determine the average atomic mass of Nickel, the equation would be:
Average atomic mass = ∑Abundance×Atomic Mass

Using the equation, the answer would be:
Average atomic mass = 57.9353(68.0769%) + 59.9308(26.2231%) + 60.9311(1.1399%) + 61.9283(3.6345%) + 63.9280(0.9256%)

Average atomic mass = 58.6933 amu