Mass Spectroscopy of the Elements - AP Chemistry
Card 1 of 377
Which of the following describes an isotope to 
?
Which of the following describes an isotope to
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An element is defined by the number of protons it contains. An isotope is the same element with a different number of neutrons; only two choices have six protons, which carbon has. One of them is 13C, which is the same as the question; the other is 12C.
Note that the question asks for an isotope to 13C. By definition, our answer choice cannot be 13C, but must be a variation (an isotope). We are looking for a second answer with 6 protons, in order to maintain the elemental identity of carbon, but a different number of neutrons (not 7). This makes our final answer a carbon atom with 7 protons, 6 neutrons, or 12C, because it is an isotope to 13C.
An element is defined by the number of protons it contains. An isotope is the same element with a different number of neutrons; only two choices have six protons, which carbon has. One of them is 13C, which is the same as the question; the other is 12C.
Note that the question asks for an isotope to 13C. By definition, our answer choice cannot be 13C, but must be a variation (an isotope). We are looking for a second answer with 6 protons, in order to maintain the elemental identity of carbon, but a different number of neutrons (not 7). This makes our final answer a carbon atom with 7 protons, 6 neutrons, or 12C, because it is an isotope to 13C.
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Which of the following is an isotope of Fluorine-20
Which of the following is an isotope of Fluorine-20
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isotopes have more neutrons, but their protons are the same
isotopes have more neutrons, but their protons are the same
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Which of the following contains the most neutrons?
Which of the following contains the most neutrons?
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The number following the compound is the isotope number, giving the number of protons and neutrons the element contains per atom. To get the number of neutrons you take the isotope number and subtract the atomic number of that element.
The number following the compound is the isotope number, giving the number of protons and neutrons the element contains per atom. To get the number of neutrons you take the isotope number and subtract the atomic number of that element.
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What is the sum of the number of neutrons of the following atoms: (a) N15
(b) Ag109 (c) Si30
What is the sum of the number of neutrons of the following atoms: (a) N15
(b) Ag109 (c) Si30
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In an atomic representation, the number of neutrons and protons is the upper number
and the number of protons is the lower number. If only one number is given, we can assume
that the number of protons is its atomic number. Therefore (a) 7 protons and 8 neutrons
(b) 47 protons and 62 neutrons (c) 14 protons and 16 neutrons. The total number is 86.
In an atomic representation, the number of neutrons and protons is the upper number
and the number of protons is the lower number. If only one number is given, we can assume
that the number of protons is its atomic number. Therefore (a) 7 protons and 8 neutrons
(b) 47 protons and 62 neutrons (c) 14 protons and 16 neutrons. The total number is 86.
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Which of the following is NOT an isotope of oxygen
Which of the following is NOT an isotope of oxygen
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O2- is an ion, and not an isotope; an isotope has the same number of protons and electrons, but a different number of neutrons
O2- is an ion, and not an isotope; an isotope has the same number of protons and electrons, but a different number of neutrons
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A certain element X is comprised of isotopes A, B, and C. Isotope A has a mass of 50 amu and is 70% of naturally occurring X. Isotope B is 35 amu and is 25% of X. Isotope C has a mass of 70 amu and is 5% of X. What is the atomic weight of element X?
A certain element X is comprised of isotopes A, B, and C. Isotope A has a mass of 50 amu and is 70% of naturally occurring X. Isotope B is 35 amu and is 25% of X. Isotope C has a mass of 70 amu and is 5% of X. What is the atomic weight of element X?
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0.70 (50 amu) + 0.25 (35 amu) + 0.05 (70 amu) = 47 amu = 47 g/mol
0.70 (50 amu) + 0.25 (35 amu) + 0.05 (70 amu) = 47 amu = 47 g/mol
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Which of the following is not a subatomic particle?
Which of the following is not a subatomic particle?
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Protons, neutrons, and electrons are all subatomic particles. Alpha particles consist of 2 protons and 2 neutrons bound together in a particle. It is usually emitted during fission reactions.
Protons, neutrons, and electrons are all subatomic particles. Alpha particles consist of 2 protons and 2 neutrons bound together in a particle. It is usually emitted during fission reactions.
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What is the formal charge on the N atom in the \[NH4\]+ ion?
What is the formal charge on the N atom in the \[NH4\]+ ion?
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N has 5 valence electrons. In the ion, N has 4 bonds, and thus 8 bonding electrons and 0 nonbonding electrons. Thus, formal charge = 5- (1/2)*8 - 0 = 1.
N has 5 valence electrons. In the ion, N has 4 bonds, and thus 8 bonding electrons and 0 nonbonding electrons. Thus, formal charge = 5- (1/2)*8 - 0 = 1.
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Which of the following isotopes has the greatest number of neutrons?
Which of the following isotopes has the greatest number of neutrons?
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Carbon-14 has 8 neutrons
Nitrogen-13 has 6 neutrons
Oxygen-15 has 7 neutrons
Fluorine-16 has 7 neutrons
Boron-10 has 5 neutrons
Carbon-14 has 8 neutrons
Nitrogen-13 has 6 neutrons
Oxygen-15 has 7 neutrons
Fluorine-16 has 7 neutrons
Boron-10 has 5 neutrons
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What is the correct notation of the isotope of nitrogen with 8 neutrons?
What is the correct notation of the isotope of nitrogen with 8 neutrons?
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The denotation is element name-proton+neutron. With 7 protons and 8 neutrons, this necomes Nitrogen-15.
The denotation is element name-proton+neutron. With 7 protons and 8 neutrons, this necomes Nitrogen-15.
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Which of the following molecules has an O atom with the most negative formal charge?
Which of the following molecules has an O atom with the most negative formal charge?
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For the carbonate ion, there are 3 resonance structures, and each of the 3 oxygen atoms carries a formal charge of –1 in two out of the three structures. This means that there is a –2/3 charge on each O atom. There are no formal charges in H2O or O2. and in O3, the central O has a positive charge and each outer O has a negative charge, so there is an average charge of –1/2 on the two outer ones.
For the carbonate ion, there are 3 resonance structures, and each of the 3 oxygen atoms carries a formal charge of –1 in two out of the three structures. This means that there is a –2/3 charge on each O atom. There are no formal charges in H2O or O2. and in O3, the central O has a positive charge and each outer O has a negative charge, so there is an average charge of –1/2 on the two outer ones.
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A Carbon-12 atom that has gained a neutron and lost an electron can be described as:
A Carbon-12 atom that has gained a neutron and lost an electron can be described as:
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Isotopes are examples of the same element existing with different amounts of nuetrons. When an atom gains a neutron, a different isotope of this atom has been formed. Ions are atoms that have either completely lost or completely gained an electron when compared to their ground state configuration. Here the atom has lost an electron and is thus a positive ion.
Isotopes are examples of the same element existing with different amounts of nuetrons. When an atom gains a neutron, a different isotope of this atom has been formed. Ions are atoms that have either completely lost or completely gained an electron when compared to their ground state configuration. Here the atom has lost an electron and is thus a positive ion.
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The average molecular weight for element X is 59.97 g/mol. There are two known isotopes of element X, one weighing 59 g/mol, and the other weighing 61 g/mol. What is the relative abundance of each?
The average molecular weight for element X is 59.97 g/mol. There are two known isotopes of element X, one weighing 59 g/mol, and the other weighing 61 g/mol. What is the relative abundance of each?
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In this simplistic case, we only have two isotopes, so we know the following:
Where "n" represents the relative abundance of X-59, and "(1-n)" is the relative abundance of X-61. We will algebraically solve for "n":
simplifies to
simplifies to
which leads to
If "n" is equal to 0.515, that means the relative abundance of X-59 is 51.5%, and thus the relative abundance of X-61 is 48.5%.
In this simplistic case, we only have two isotopes, so we know the following:
Where "n" represents the relative abundance of X-59, and "(1-n)" is the relative abundance of X-61. We will algebraically solve for "n":
If "n" is equal to 0.515, that means the relative abundance of X-59 is 51.5%, and thus the relative abundance of X-61 is 48.5%.
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Arbitrary element, X, has two isotopes, 
and 
. The mass listed on the periodic table is 8.000 grams per mole. Without doing any calculations, which isotope is more abundant?
Arbitrary element, X, has two isotopes,
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A calculation would show that the relative abundance of each is 50%, you can see that 8.000 g/mol is exactly the midpoint between the masses of 7 and 9, so each has to be present in equal quantities.
A calculation would show that the relative abundance of each is 50%, you can see that 8.000 g/mol is exactly the midpoint between the masses of 7 and 9, so each has to be present in equal quantities.
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Chemical 
has only two isotopes: 
and 
. The atomic weight of chemical X, listed on the periodic table, is 
. What is the relative abundance of each isotope?
Chemical
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The abundance of 
will be referred to as "n," and the abundance of 
is "1-n." Together, we know that these values account for the full abundance of chemical X in existence.
The abundance of 
is 96.25%, and the abundance of 
is 3.75%.
The abundance of
The abundance of
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Which of the following ions or atoms is isoelectronic with neon?
Which of the following ions or atoms is isoelectronic with neon?
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Neon has an electron configuration of 1s22s22p6, just like O2-. Sodium has one extra electron, while magnesium has two extra electrons, beyond the neon configuration. Finally, the electron configuration for Cl- is 1s22s22p63s23p6. It is one period below flourine; F- would be isoelectric with neon.
Neon has an electron configuration of 1s22s22p6, just like O2-. Sodium has one extra electron, while magnesium has two extra electrons, beyond the neon configuration. Finally, the electron configuration for Cl- is 1s22s22p63s23p6. It is one period below flourine; F- would be isoelectric with neon.
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Which of the following statements is true?
Which of the following statements is true?
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Electrons are notably smaller than nucleons (protons and neutrons), however, they have an equal amount of charge to protons. This is why an atom with the same amount of protons as electrons is considered electrically neutral.
The nucleus itself is positively charged, as the electrons are located relatively far away from the atomic center.
Electrons are notably smaller than nucleons (protons and neutrons), however, they have an equal amount of charge to protons. This is why an atom with the same amount of protons as electrons is considered electrically neutral.
The nucleus itself is positively charged, as the electrons are located relatively far away from the atomic center.
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Many elements exist in nature as varying isotopes. Although one isotope commonly predominates due to stability, the other isotopes can affect the overall mass of one natural mole of the element.
Suppose a mystery element has two main isotopes: isotope X has a molar mass of 128 grams per mole and isotope Y has a molar mass of 132 grams per mole. One mole of this element, when found naturally, weighs 128.8 grams. What are the percentages of isotopes X and Y when found in nature?
Many elements exist in nature as varying isotopes. Although one isotope commonly predominates due to stability, the other isotopes can affect the overall mass of one natural mole of the element.
Suppose a mystery element has two main isotopes: isotope X has a molar mass of 128 grams per mole and isotope Y has a molar mass of 132 grams per mole. One mole of this element, when found naturally, weighs 128.8 grams. What are the percentages of isotopes X and Y when found in nature?
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This answer becomes a lot easier if we use some quick mental math. First, notice that if the two isotopes were equal in nature (50/50), than a mole would weigh 130 grams.
Since the number is less than that, we can conclude that isotope X is more dominant than isotope Y, lowering the average mass. Now, we can use math to find the exact percentage.
Start by realizing that isotope X will make up some percentage of the element in nature (we will call this percentage "A") while isotope Y will make up the rest of that percentage (1-A).
This means that 80% of the element is composed of isotope X, and the other 20% is composed of isotope Y. Going back to our mental math, we see that, just as we predicted, isotope X is present in a larger amount than isotope Y.
This answer becomes a lot easier if we use some quick mental math. First, notice that if the two isotopes were equal in nature (50/50), than a mole would weigh 130 grams.
Since the number is less than that, we can conclude that isotope X is more dominant than isotope Y, lowering the average mass. Now, we can use math to find the exact percentage.
Start by realizing that isotope X will make up some percentage of the element in nature (we will call this percentage "A") while isotope Y will make up the rest of that percentage (1-A).
This means that 80% of the element is composed of isotope X, and the other 20% is composed of isotope Y. Going back to our mental math, we see that, just as we predicted, isotope X is present in a larger amount than isotope Y.
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Which of the following is a set of isotopes?
Which of the following is a set of isotopes?
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Isotopes are members of the same element that have a different number of neutrons, and therefore a different atomic weight. The number shown in the top left is always the number of protons plus neutrons (atomic weight), so we can show that an element is an isotope by increasing or decreasing that number.
There are three main isotopes of carbon: carbon-12, carbon-13, and carbon-14. The identity of the element must not change, only the atomic weight. The other answer choices are other types of related chemicals; note that ions are not isomers.
Isotopes are members of the same element that have a different number of neutrons, and therefore a different atomic weight. The number shown in the top left is always the number of protons plus neutrons (atomic weight), so we can show that an element is an isotope by increasing or decreasing that number.
There are three main isotopes of carbon: carbon-12, carbon-13, and carbon-14. The identity of the element must not change, only the atomic weight. The other answer choices are other types of related chemicals; note that ions are not isomers.
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An element has two main isotopes. The first isotope has a molar mass of 125 grams, and the second isotope has a molar mass of 128 grams. A naturally occurring sample of the element has a molar mass of 126.8 grams.
What is the lighter isotope's percentage in the natural sample?
An element has two main isotopes. The first isotope has a molar mass of 125 grams, and the second isotope has a molar mass of 128 grams. A naturally occurring sample of the element has a molar mass of 126.8 grams.
What is the lighter isotope's percentage in the natural sample?
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In order to find the percentage of the lighter isotope in the natural sample, we need to use an equation that compares the percentage of each isotope and the natural molar mass. Since both of the isotopes together will account for 100% of the natural sample, we can say that the lighter isotope's percentage is 
, while the remaining percentage is 
.
Use this equation to solve for 
.
In other words, we can conclude that the lighter isotope makes up 40% of the natural sample.
In order to find the percentage of the lighter isotope in the natural sample, we need to use an equation that compares the percentage of each isotope and the natural molar mass. Since both of the isotopes together will account for 100% of the natural sample, we can say that the lighter isotope's percentage is
Use this equation to solve for
In other words, we can conclude that the lighter isotope makes up 40% of the natural sample.
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