An atom of 125sn has a mass of 124.907785 amu. calculate the mass defect (deficit) in amu/atom. use the masses: mass of 1h atom = 1.007825 amu mass of a neutron = 1.008665 amu 1 amu = 931.5 mev give your answer to 4 significant figures and do not use e notation..

The mass defect is 1.133 amu/atom

Explanation:

The given element is:-  

Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.

Also, atomic number of Sn = 50

Thus, the number of protons = 50

Mass number is the number of the entities present in the nucleus which is the equal to the sum of the number of protons and electrons.

Mass number = Number of protons + Number of neutrons

125 =  50 + Number of neutrons

Number of neutrons = 75

Mass of neutron = 1.008665 amu

Mass of proton = 1.007825 amu

Calculated mass = Number of protons*Mass of proton + Number of neutrons*Mass of neutron

Thus,  

Calculated mass = (50*1.007825 + 75*1.008665) amu = 126.041125 amu

Given, mass = 124.907785 amu

Mass defect = Δm = |126.041125 - 124.907785 | amu = 1.13334 amu

Hence, the mass defect is 1.133 amu/atom

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