Nuclear, Quantum, and Molecular Chemistry - Physical Chemistry
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Which atomic symbol represents a period five transition metal that has 42 electrons when it forms a 
cation?
Which atomic symbol represents a period five transition metal that has 42 electrons when it forms a
Transition metals extend from groups 3 through 12 and periods 4 through 7. Ru, in its neutral state, has 44 electrons. Therefore, when it becomes a 
cation, it will have 42 electrons.
Transition metals extend from groups 3 through 12 and periods 4 through 7. Ru, in its neutral state, has 44 electrons. Therefore, when it becomes a
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How many neutrons are present in the nucleus of one atom of 
?
How many neutrons are present in the nucleus of one atom of
From the periodic table, we find that the atomic number, i.e., the number of protons in the nucleus of 
is 15. Given that the mass number is 32, and recalling the formula which relates mass number to the number of neutrons and protons: 
, we find that the number of neutrons in the nucleus of one atom of 
is 17.
From the periodic table, we find that the atomic number, i.e., the number of protons in the nucleus of
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What is the mass number, atomic number, and charge, of the isotope of an atom that contains 34 protons, 36 neutrons, and 36 electrons?
What is the mass number, atomic number, and charge, of the isotope of an atom that contains 34 protons, 36 neutrons, and 36 electrons?
The atomic number is equal to the number of protons in the element, so from the periodic table, we find that the element with atomic number 34 is selenium. Since 
, we calculate that the mass number is 70. Lastly, there are two more electrons than protons, so the charge will be 
.
The atomic number is equal to the number of protons in the element, so from the periodic table, we find that the element with atomic number 34 is selenium. Since
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Which of the following electron configurations indicates an atom in an excited state?
Which of the following electron configurations indicates an atom in an excited state?
An atom is considered to be in an excited state when one of the electrons has jumped to a higher energy level while a lower energy level is available. In the case of 
, an electron has jumped to the 2p energy level while there is still room in the lower 2s subshell. As a result, it is considered to be in an excited state.
An atom is considered to be in an excited state when one of the electrons has jumped to a higher energy level while a lower energy level is available. In the case of
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What is the complete ground state electron configuration for the magnesium atom?
What is the complete ground state electron configuration for the magnesium atom?
Magnesium has an atomic number of 12, so the total number of electrons in its configuration should add up to twelve. The maximum number of electrons in the s subshell is two. Of all the answer choices, only 1s22s22p63s 2 fits the criteria. The sum of the exponent values is 12, matching the atomic number of magnesium, and the number of electrons in the s and p subshells matches the maximum amount possible.
Magnesium has an atomic number of 12, so the total number of electrons in its configuration should add up to twelve. The maximum number of electrons in the s subshell is two. Of all the answer choices, only 1s22s22p63s 2 fits the criteria. The sum of the exponent values is 12, matching the atomic number of magnesium, and the number of electrons in the s and p subshells matches the maximum amount possible.
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What is the complete ground state electron configuration for the iron atom?
What is the complete ground state electron configuration for the iron atom?
Iron has an atomic number of 26, so the total number of electrons in its configuration should add up to twenty six. The maximum number of electrons in the s subshell is two. The sum of the exponent values is 26, matching the atomic number of magnesium, and the number of electrons in the s and p subshells matches the maximum amount possible.
Iron has an atomic number of 26, so the total number of electrons in its configuration should add up to twenty six. The maximum number of electrons in the s subshell is two. The sum of the exponent values is 26, matching the atomic number of magnesium, and the number of electrons in the s and p subshells matches the maximum amount possible.
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In an atom or molecule, why can't two electrons have the same four electronic quantum numbers?
In an atom or molecule, why can't two electrons have the same four electronic quantum numbers?
The Pauli Exclusion Principle explains various phenomena such as the structure of atoms and how different atoms combine to share electrons. When you have two electrons that are located in the same orbital, the quantum numbers n, l and ml are the same. However, ms will be different. Two electrons cannot have the same four electronic quantum numbers because no more than two electrons may occupy an orbital, and if they do, the spin of one must cancel the spin of the other so their spins will have a zero net spin angular momentum.
The Pauli Exclusion Principle explains various phenomena such as the structure of atoms and how different atoms combine to share electrons. When you have two electrons that are located in the same orbital, the quantum numbers n, l and ml are the same. However, ms will be different. Two electrons cannot have the same four electronic quantum numbers because no more than two electrons may occupy an orbital, and if they do, the spin of one must cancel the spin of the other so their spins will have a zero net spin angular momentum.
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Which of the following organizes the forces from strongest to weakest?
Which of the following organizes the forces from strongest to weakest?
Covalent bonds are by far the strongest, requiring 
to be broken.
Next are hydrogen bonds, which require between 
to be broken.
Next are dipole-dipole interactions, which require 
to be broken.
Finally, van der Waals forces are the weakest of those listed, requiring 
to be broken.
Covalent bonds are by far the strongest, requiring
Next are hydrogen bonds, which require between
Next are dipole-dipole interactions, which require
Finally, van der Waals forces are the weakest of those listed, requiring
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What is the hybridization on the nitrogen atom in a molecule of ammonia?
What is the hybridization on the nitrogen atom in a molecule of ammonia?
The hybridization of an atom can be determined by the number of atoms it is bonded to, as well as the number of lone pairs it has. Two of these variables would be sp, three variables would be sp2, and four would be sp3.
The nitrogen in ammonia is bonded to three atoms of hydrogen, but also has a lone pair in order to satisfy its octet. This means that nitrogen exhibits sp3 hybridization.
The hybridization of an atom can be determined by the number of atoms it is bonded to, as well as the number of lone pairs it has. Two of these variables would be sp, three variables would be sp2, and four would be sp3.
The nitrogen in ammonia is bonded to three atoms of hydrogen, but also has a lone pair in order to satisfy its octet. This means that nitrogen exhibits sp3 hybridization.
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Which of the following are true regarding 
and 
orbitals?
I. Both 
and 
orbitals can contain a maximum of two electrons
II. In a given shell, 
orbitals are more numerous because they are spherical in shape
III. 
orbitals have lower energy than 
orbitals within the same shell
Which of the following are true regarding
I. Both
II. In a given shell,
III.
Orbitals are regions in an electron shell where electrons might be located. There are several types of orbitals such as 
, and 
. Most elements found on the periodic table contain electrons within one of these orbitals. A characteristic of an orbital is that it can only contain two electrons maximum. A shell might contain multiple orbitals; however, each orbital can only contain two electrons. Each orbital has a unique shape that corresponds to the electron density (the possible location of an electron at a given point in time). The 
orbital has a spherical shape whereas the 
orbital has a dumbbell shape. As mentioned, a shell can contain multiple types of orbitals. A shell can typically contain one 
orbital, three 
orbitals, five 
orbitals, and seven 
orbitals. Remember that the shape of the orbital has no bearing on the amount of orbitals in a shell. An orbital is higher in energy if it is found farther away from the nucleus. The orbitals in order of increasing energy is as follows 
. Therefore, an 
orbital has lower energy than a 
orbital in the same shell.
Orbitals are regions in an electron shell where electrons might be located. There are several types of orbitals such as
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What is true when comparing the electron configuration of elemental sodium 
and sodium cation 
?
What is true when comparing the electron configuration of elemental sodium
To answer this question, we need to find the electron configuration of both elemental sodium and sodium cation. If we look at the periodic table we can see that sodium is found on the first column. Since it is found in the first column, sodium has one valence electron. To complete octet, sodium will readily lose an electron and become a positively charged sodium ion. The electron configuration for sodium is 
. The electron configuration for sodium ion is 
(because it lost its electron in the 
orbital). This means that elemental sodium has an unpaired electron in its 
orbital; the sodium ion has no unpaired electrons. Recall that an unpaired electron can generate its own magnetic field and is called paramagnetic; therefore, solid sodium is paramagnetic. The number of electrons in the 
orbitals for both sodium and sodium ion is the same (6 electrons total in the 
orbital). The outermost shell of sodium is the third shell (because sodium is located on the third row of periodic table). Elemental sodium contains one electron in the 
orbital in the outermost shell whereas the sodium ion contains 6 electrons in its outermost shell.
To answer this question, we need to find the electron configuration of both elemental sodium and sodium cation. If we look at the periodic table we can see that sodium is found on the first column. Since it is found in the first column, sodium has one valence electron. To complete octet, sodium will readily lose an electron and become a positively charged sodium ion. The electron configuration for sodium is
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It is observed that a molecule has three hybridized orbitals in its outermost shell. What can you conclude about this molecule?
It is observed that a molecule has three hybridized orbitals in its outermost shell. What can you conclude about this molecule?
Hybridization is a process involving the fusion, or hybridization, of 
and 
orbitals to form a unique orbital. It is possible for various combinations of 
and 
hybridization. Recall that there is one 
orbital and three 
orbitals in each shell. This means that the one 
orbital can hybridize with 1, 2, or all 3 
orbitals. Since there are three total combinations, there are three types of hybridized orbitals. These are 
, 
, and 
. 
orbital has one 
and one 
orbital hybridized. This means that the 
orbital and the first 
orbital become a new 
orbital. A molecule with 
hybridization will have two 
orbitals and two 
orbitals. Similarly, an 
orbital is made from the hybridization of one 
and two 
orbitals. In 
hybridization, there are three 
orbitals and one 
orbital. Finally, an 
orbital has one 
and all three 
orbitals; therefore, an 
hybridized molecule will have four 
orbitals and no 
orbitals. The question states that there are three hybridized orbitals in this molecule; therefore, this molecule must be 
hybridized. The single 
orbital is unhybridized because the molecule probably has a double bond. Electrons in 
bonds in double and triple bonds cannot be found in hybridized orbitals; therefore, they need their own 
orbital. If a molecule has one 
bond (double bond), then it will need one 
orbital and will be 
hybridized (because this will give three 
hybridized orbitals and one 
orbital). If it has two 
bonds (triple bond), then it will need two 
orbitals and will be 
hybridized. If a molecule has all 
bonds (single bonds), then the molecule will require no empty 
orbitals for the delocalized electrons, and will be 
hybridized.
Hybridization is a process involving the fusion, or hybridization, of
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Which of the following is true regarding carbon tetrachloride?
Which of the following is true regarding carbon tetrachloride?
Carbon tetrachloride, 
, has a central carbon atom attached to four chlorine atoms. The bonds between the carbon atom and chlorine atoms are single covalent bonds. The electrons in a single bond (
bond) can be found in hybridized orbitals. Since carbon tetrachloride only has single bonds, the carbon atom can hybridize all of its orbitals (one 
and three 
) in the outermost shell and form a 
hybridization; therefore, three 
orbitals and one 
orbital participate in hybridization leading us to the correct answer. Carbon dioxide, 
, has a central carbon atom bonded to two oxygen atoms. To complete octet, carbon and oxygen atoms have double bonds. This means that carbon dioxide has two 
bonds (two double bonds). Recall that electrons in 
bonds cannot reside in hybridized orbitals; therefore, to accommodate the two 
bonds we need two empty, unhybridized 
orbitals. This means that carbon dioxide will have hybridization of one 
and one 
orbital, giving it an 
hybridization.
Carbon tetrachloride,
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Which of the following represents the alkaline earth metal with the greatest atomic number?
Which of the following represents the alkaline earth metal with the greatest atomic number?
Alkaline earth metals are group II elements; among them, radium has the largest atomic number.
Alkaline earth metals are group II elements; among them, radium has the largest atomic number.
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Which of the following isotopes has the most neutrons?
Which of the following isotopes has the most neutrons?
this notation is commononly used in chemistry where 
represents the mass number, and 
represents the atomic number of element 
.
To find the number of neutrons in each isotope, subtract the atomic number from the mass number.
Thus for 
, the number of neutrons is 67. This isotope has the most neutrons among the answer choices.
To find the number of neutrons in each isotope, subtract the atomic number from the mass number.
Thus for
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How many protons, neutrons and electrons are there in a neutral atom of the copper 
isotope represented by a mass number of 65 and an atomic number of 29?
How many protons, neutrons and electrons are there in a neutral atom of the copper
The number of protons for any atom is the same as the atomic number on the periodic table. Therefore, any isotope of copper will have 29 protons. Since the atom is neutral, the number of protons must be equal to the number of electrons. To find the number of neutrons, subtract the number of protons from the mass number to get 36 neutrons.
The number of protons for any atom is the same as the atomic number on the periodic table. Therefore, any isotope of copper will have 29 protons. Since the atom is neutral, the number of protons must be equal to the number of electrons. To find the number of neutrons, subtract the number of protons from the mass number to get 36 neutrons.
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How many protons, neutrons and electrons are there in a neutral atom of the isotope of lithium-6?
How many protons, neutrons and electrons are there in a neutral atom of the isotope of lithium-6?
The number of protons is equal to the atomic number on the periodic table. For lithium, this number is 3. Since this isotope is neutral, the number of electrons must be equal to the number of protons. To find the number of neutrons, subtract the number of protons from the mass number to obtain 3. The notation "lithium-6" indicates that the mass number of this isotope is 6.
The number of protons is equal to the atomic number on the periodic table. For lithium, this number is 3. Since this isotope is neutral, the number of electrons must be equal to the number of protons. To find the number of neutrons, subtract the number of protons from the mass number to obtain 3. The notation "lithium-6" indicates that the mass number of this isotope is 6.
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An ion from a given element has 13 protons and 10 electrons. What is the symbol of the ion?
An ion from a given element has 13 protons and 10 electrons. What is the symbol of the ion?
The charge on the ion is equal to the difference between the number of protons and electrons:
The element has 13 protons, which means its atomic number is also 13. Thus this element is aluminum.
The charge on the ion is equal to the difference between the number of protons and electrons:
The element has 13 protons, which means its atomic number is also 13. Thus this element is aluminum.
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An ion of a given element has 35 protons and 36 electrons. What is the symbol of the ion?
An ion of a given element has 35 protons and 36 electrons. What is the symbol of the ion?
The charge on the ion is equal to the difference between the number of protons and electrons.
The element has 35 protons, thus its atomic number is 35, which corresponds to bromine.
The charge on the ion is equal to the difference between the number of protons and electrons.
The element has 35 protons, thus its atomic number is 35, which corresponds to bromine.
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The __________ Principle states that electrons fill lower energy levels before filling higher energy levels and __________ Rule says that electrons fill electron orbitals within a subshell singly if possible before pairing up.
The __________ Principle states that electrons fill lower energy levels before filling higher energy levels and __________ Rule says that electrons fill electron orbitals within a subshell singly if possible before pairing up.
Aufbau's Principle says that electrons fill lower energy levels first. Hund's Rule dictates that electrons fill singly if possible.
Aufbau's Principle says that electrons fill lower energy levels first. Hund's Rule dictates that electrons fill singly if possible.
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