Chapter 19, Problem 47E

Interpretation Introduction

Interpretation:

Given the mass defect of $Li$ nucleus its atomic mass has to be calculated.

Concept Introduction:

Atomic mass of an atom is often referred to as the sum of number of protons and number of neutrons.  But the actual mass of nucleus is not equivalent to the sum of number of protons and number of neutrons.  The difference between these two is called mass defect which occurs due to the loss of energy during the formation of nucleus. It is represented as,

$\begin{array}{l}\Delta m=[Z(m_p +m_e)+\left(A-Z\right)m_n ]-m_{atom}\\ \Delta m\text{ = mass defect, Z = atomic number(number of protons), A = mass number}\\ {\text{m}}_p{\text{ = mass of proton, m}}_e{\text{ = mass of electron, m}}_n\text{ = mass of neutron}\\ m_{atom}=\text{ mass of nuclide }\text{X}\end{array}$