Question

An atom of 64Ni has an experimentally determined nuclear mass of 63.9280 amu. Calculate the mass defect, Δm, in atomic mass units (amu).

Answer 1

The atomic number of Ni =28

Number of protons =28

Mass number of Ni = 64

Therefore number of neturons =64-28 = 36

Mass of one proton = 1.0072765 amu

Mass of one neutron = 1.0086650 amu

Mass of one electron = 0.00054858 amu

Predicted mass of given isotope of Ni = Mass of all protons + mass of all neutrons + mass of all electrons

Predicted mass= 28 X ( 1.0072765) + 36 X (1.0086650 )+ 28 X (0.00054858)

Mass = 28.203742 + 36.31194 + 0.015360 = 63.531042 amu

Exact mass of Ni atom = 63.9280 amu

Mass defect = 63.9280 amu - 63.531042 amu = 0.6030 amu