Question

q1 chemistry: u2l8 mastery quiz 1 practice
mad minute annotating mass spectra
directions: annotate each mass spectra with the following.
peak with greatest number of neutrons
peak with greatest percent abundance
how many isotopes are present in each mass spectra?
identity of the element (use your periodic table)
1.**
identity: circle one
a. beryllium (be)
b. boron (b)
c. zirconium (zr)
d. yttrium (y)
teacher use only
score %
1/4 25
/4 50
/4 75
/4 100

Explanation:

Step1: Identify peak with greatest percent - abundance

The tallest peak in the mass - spectrum represents the peak with the greatest percent abundance. Here, the peak at m/z = 90 has the greatest relative abundance.

Step2: Determine number of isotopes

The number of peaks in the mass - spectrum represents the number of isotopes. There are 5 peaks, so there are 5 isotopes.

Step3: Find peak with greatest number of neutrons

Neutrons \(n=m - p\), where \(m\) is the mass number and \(p\) is the atomic number. We need to consider the atomic numbers of the elements in the options. Beryllium (\(Be\), \(p = 4\)), Boron (\(B\), \(p = 5\)), Zirconium (\(Zr\), \(p = 40\)), Yttrium (\(Y\), \(p = 39\)). For a given mass number \(m\), the element with the highest atomic number will have the fewest neutrons. Among the options, Zirconium has the highest atomic number. The highest mass - to - charge ratio peak here is around \(m/z=98\). For Zirconium (\(Zr\), \(p = 40\)), if \(m = 98\), then \(n=98 - 40=58\).

Step4: Identify the element

The mass - to - charge ratios of the isotopes are around 90, 92, 94, 96, 98. Looking at the periodic table, Zirconium (\(Zr\)) has isotopes with these approximate mass numbers.

Answer:

Peak with greatest number of neutrons: The peak at m/z = 98
Peak with greatest percent abundance: The peak at m/z = 90
How many isotopes are present: 5
Identity of the element: C. Zirconium (Zr)