Chapter 14, Problem 14.10P

Interpretation Introduction

Interpretation:

In which rule expect for the $m/z$ values of fragment ions resulting from the cleavage of one bond in a compound with an odd number of nitrogen atoms. The reason behind this has to be given.

Concept Introduction:

Nitrogen rule: The nitrogen rule states, that a molecule that has no or even number of nitrogen atoms has an even nominal mass, whereas a molecule that has a odd number of nitrogen atoms has an odd nominal mass.

	$\begin{array}{l}\text{Molecular}\text{formula}\text{=}{\text{CH}}_{\text{4}}\text{O}\\ \text{Nominal}\text{mass}\text{=}\text{(1×12)+(4×1)+(1×16)}\\ \text{=}\text{32}\\ \text{The}\text{nitrogen}\text{atoms}\text{=0}\\ \text{Nominal}\text{mass}\text{=32}\text{it}\text{is}\text{even}\end{array}$
	$\begin{array}{l}\text{Molecular}\text{formula}\text{=}{\text{CH}}_5\text{N}\\ \text{Nominal}\text{mass}\text{=}\text{(1×12)+(5×1)+(1×14)}\\ \text{=}\text{31}\\ \text{The}\text{nitrogen}\text{atoms}\text{=0}\\ \text{Nominal}\text{mass}\text{=31}\text{it}\text{is}\text{odd}\end{array}$

Nominal mass: The nominal mass for an element is the mass number of it is most abundant naturally occurring stable isotope and for an ion or given molecule the nominal mass is the sum of the nominal masses of the constituent atoms.

Example: The exact mass of the most abundant isotopes of each element

For example hydrogen  $\text{H}\text{=}1.007825$