Multiple Choice
Which of the following is the number of protons in a boron atom?
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2. Atoms & Elements
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Which of the following best explains why the mass spectrum of chlorine shows two major peaks at approximately 35 and 37 atomic mass units?
A
Chlorine atoms always lose two neutrons during ionization, resulting in two peaks.
B
The mass spectrum reflects the presence of chlorine molecules, Cl2, with different masses.
C
The instrument error causes the appearance of two peaks for a single isotope.
D
Chlorine has two stable isotopes, Cl-35 and Cl-37, with significant natural abundances.
Verified step by step guidance1
Understand that a mass spectrum displays the masses of ions detected, which correspond to the isotopes of an element present in the sample.
Recall that chlorine naturally exists as a mixture of two stable isotopes: chlorine-35 and chlorine-37, each with a different number of neutrons and thus different atomic masses.
Recognize that these isotopes produce separate peaks in the mass spectrum because the instrument detects ions based on their mass-to-charge ratio, so ions of Cl-35 and Cl-37 appear at different positions.
Note that the relative heights of the peaks correspond to the natural abundances of these isotopes, which is why both peaks are significant and prominent.
Conclude that the two major peaks at approximately 35 and 37 atomic mass units in the chlorine mass spectrum are due to the presence of these two stable isotopes, not due to ionization losses, molecular forms, or instrument error.
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