Ch.2 - Atoms & ElementsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Mass Spectrometry allows you to determine the molecular weight of an unknown compound through its vaporization and ionization. 

Mass Spectrometer

mass spectrometer is used to determine the mass to charge ratio of an unknown compound. 

Concept #1: A mass spectrometer operates under a very high vacuum while the sample is introduced. 

mass spectrometer involves three primary functions: 

1) The vaporization of your unknown compound M into gas M. 

2) The ionization of gas M into the molecular ion or radical cation. 

3) The detection of all gas ion fragments. 

Analysis of all the gaseous ions helps to create a mass spectrum. 

Additional Problems
For the next three questions consider a 10 L sample of gaseous chlorine atoms in their natural relative abundances (3:1 35Cl : 37Cl). The Cl atoms react to form Cl2 gas. Which is the most likely mass spectrum of the products?
Consider the mass spectrometer show below. Determine whether each of the following statements is true or false.The paths of neutral (uncharged) atoms are not affected by the magnet.
Consider the mass spectrometer show below. Determine whether each of the following statements is true or false.The height of each peak in the mass spectrum is directly proportional to the relative abundance of the isotope.
Consider the mass spectrometer show below. Determine whether each of the following statements is true or false.For a given element, the number of peaks in the spectrum is equal to the number of naturally occurring isotopes of that element.
Use the mass spectrum of lead to estimate the atomic mass of lead.
Use the mass spectrum of mercury to estimate the atomic mass of mercury. Estimate the masses and percent intensity values from the graph to three significant figures.
Mass spectrometry is more often applied to molecules than to atoms. We will see in Chapter 3 in the textbook that the molecular weight of a molecule is the sum of the atomic weights of the atoms in the molecule. In mass spectrometry, these molecular weights are measured relative to 1/12 the mass of one atom of 12C and therefore are commonly referred to as relative masses. The mass spectrum of H2 is taken under conditions that prevent decomposition into H atoms. The two naturally occurring isotopes of hydrogen are 1H (atomic mass = 1.00783 amu; abundance 99.9885%) and 2H (atomic mass = 2.01410 amu; abundance 0.0115%).How many peaks will the mass spectrum have?
Mass spectrometry is more often applied to molecules than to atoms. We will see in Chapter 3 in the textbook that the molecular weight of a molecule is the sum of the atomic weights of the atoms in the molecule. In mass spectrometry, these molecular weights are measured relative to 1/12 the mass of one atom of 12C and therefore are commonly referred to as relative masses. The mass spectrum of H2 is taken under conditions that prevent decomposition into H atoms. The two naturally occurring isotopes of hydrogen are 1H (atomic mass = 1.00783 amu; abundance 99.9885%) and 2H (atomic mass = 2.01410 amu; abundance 0.0115%).Give the atomic masses (relative atomic mass) of each of these peaks.
Mass spectrometry is more often applied to molecules than to atoms. We will see in Chapter 3 in the textbook that the molecular weight of a molecule is the sum of the atomic weights of the atoms in the molecule. In mass spectrometry, these molecular weights are measured relative to 1/12 the mass of one atom of 12C and therefore are commonly referred to as relative masses. The mass spectrum of H2 is taken under conditions that prevent decomposition into H atoms. The two naturally occurring isotopes of hydrogen are 1H (atomic mass = 1.00783 amu; abundance 99.9885%) and 2H (atomic mass = 2.01410 amu; abundance 0.0115%).Which peak will be the largest?
Mass spectrometry is more often applied to molecules than to atoms. We will see in Chapter 3 in the textbook that the molecular weight of a molecule is the sum of the atomic weights of the atoms in the molecule. In mass spectrometry, these molecular weights are measured relative to 1/12 the mass of one atom of 12C and therefore are commonly referred to as relative masses. The mass spectrum of H2 is taken under conditions that prevent decomposition into H atoms. The two naturally occurring isotopes of hydrogen are 1H (atomic mass = 1.00783 amu; abundance 99.9885%) and 2H (atomic mass = 2.01410 amu; abundance 0.0115%).Which peak will be the smallest?
What is the label on the x-axis of a mass spectrum?
To measure the mass spectrum of an atom, the atom must first lose one or more electrons. Which would you expect to be deflected more by the same setting of the electric and magnetic fields, a Cl+ or a Cl2+ ion?
What is the label on the y-axis of a mass spectrum?
Explain how a mass spectrometer works.
What kind of information can be determined from a mass spectrum?
The natural abundance of 3 He is 0.000137 %.Based on your answer for part (b), what would need to be the precision of a mass spectrometer that is able to differentiate between peaks that are due to pandoc: Error at "source" (line 1, column 14): unexpected " " expecting "{" or "" ^3 { m{He}}^ + and ^3 { m{H}}^ +?
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 What is the mass of lighter isotope?
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 Determine the average molecular mass of a Br2 molecule.
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 Determine the average atomic mass of a bromine atom.
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 Calculate the abundance of the lighter isotope.
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 What is the origin of first (mass of 157.836 amu) peak (of what isotopes does each consist)?
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 What is the origin of second (mass of 159.834 amu) peak (of what isotopes does each consist)?
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 What is the origin of third (mass of 161.832 amu) peak (of what isotopes does each consist)?
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 What is the mass of heavier isotope?
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: Mass (amu) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 Calculate the abundance of the heavier isotope.
It is common in mass spectrometry to assume that the mass of a cation is the same as that of its parent atom.Using data in the table, determine the number of significant figures that must be reported before the difference in mass of pandoc: Error at "source" (line 1, column 55): unexpected " " expecting "{" or "" ^1 { m{H}} and ^1 { m{H}}^ + is significant. Particle Mass ({ m amu}) Proton 1.0073 Electron 5.486 imes 10^{-4}
It is common in mass spectrometry to assume that the mass of a cation is the same as that of its parent atom.What percentage of the mass of an 1 H atom does the electron represent?
The atomic mass of fluorine is 18.998 amu and its mass spectrum shows a large peak at this mass. The atomic mass of chlorine is 35.45 amu, yet the mass spectrum of chlorine does not show a peak at this mass.Explain the difference.
Use the mass spectrum of europium to determine the atomic mass of europium. Where the peak representing Eu-151 has an exact mass of 150.91986 amu and percent intensity is assumed be to exactly 91.610%, and the peak representing Eu-153 has an exact mass of 152.92138 amu and percent intensity of 100.00%.
You may want to reference (Pages 66 - 69) Section 2.8 while completing this problem.Use the mass spectrum of rubidium to determine the atomic mass of rubidium.
The atomic mass of flourine is 18.998 amu and its mass spectrum shows a large peak at this mass. The atomic mass of chlorine is 35.45 amu, yet the mass spectrum of chlorine does not show a peak at this mass. Explain the difference.
The mass spectrum of bromine (Br2) consists of three peaks with the following characteristics:How do you interpret these data?
The stable isotopes of iron are 54Fe, 56Fe, 57Fe, and 58Fe. The mass spectrum of iron looks like the following:Use the data on the mass spectrum to estimate the average atomic mass of iron, and compare it to the value given in the periodic table.
In using a mass spectrometer, a chemist sees a peak at a mass of 30.0106. Of the choices 12C21H6, 12C1H216O, and 14N16O, which is responsible for this peak? Pertinent masses are 1H, 1.007825; 16O, 15.994915; and 14N, 14.003074.
Boron consists of two isotopes, 10B and 11B. Chlorine also has two isotopes, 35Cl and 37Cl. Consider the mass spectrum of BCl 3. How many peaks would be present, and what approximate mass would each peak correspond to in the BCl3 mass spectrum?
Boron trifluoride is used as a catalyst in the synthesis of organic compounds. When this compound is analyzed by mass spectrometry (see Tools of the Laboratory: Mass Spectrometry, following Section 2.5), several different 1+ ions form, including ions representing the whole molecule as well as molecular fragments formed by the loss of one, two, and three F atoms. Given that boron has two naturally occurring isotopes, 10B and 11B, and fluorine has one, 19F, calculate the masses of all possible 1+ ions.