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 molecules does not contain polar bonds?
Which of the following molecules does not contain polar bonds?
Polar bonds form between all atoms of different electronegativity. Bromine is a diatomic molecule and thus both atoms of bromine have the same electronegativity. This bond between bromine is perfectly nonpolar, meaning that both atoms share the electron density equally.
Polar bonds form between all atoms of different electronegativity. Bromine is a diatomic molecule and thus both atoms of bromine have the same electronegativity. This bond between bromine is perfectly nonpolar, meaning that both atoms share the electron density equally.
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Which statement best characterizes a covalent bond?
Which statement best characterizes a covalent bond?
To achieve an octet of valence electrons, atoms can share electrons so that all atoms participating in the bond will have full valence shells. Covalent bonds, by definition, result from the sharing of one or more pairs of valence electrons.
To achieve an octet of valence electrons, atoms can share electrons so that all atoms participating in the bond will have full valence shells. Covalent bonds, by definition, result from the sharing of one or more pairs of valence electrons.
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How many single covalent bonds would the element sulfur be expected to form in order to obey the octet rule?
How many single covalent bonds would the element sulfur be expected to form in order to obey the octet rule?
The key to this problem is that electrons in covalent bonds are shared and therefore "belong" to both of the bonded atoms. Sulfur is a nonmetal in group 6A , and therefore has 6 valence electrons. In order to obey the octet rule, it needs to gain 2 electrons . It can do this by forming 2 single covalent bonds.
The key to this problem is that electrons in covalent bonds are shared and therefore "belong" to both of the bonded atoms. Sulfur is a nonmetal in group 6A , and therefore has 6 valence electrons. In order to obey the octet rule, it needs to gain 2 electrons . It can do this by forming 2 single covalent bonds.
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How many single covalent bonds would the element selenium be expected to form in order to obey the octet rule?
How many single covalent bonds would the element selenium be expected to form in order to obey the octet rule?
The key to this problem is that electrons in covalent bonds are shared and therefore "belong" to both of the bonded atoms. Selenium is a nonmetal in group 6A , and therefore has 6 valence electrons. In order to obey the octet rule, it needs to gain 2 electrons. It can do this by forming 2 single covalent bonds.
The key to this problem is that electrons in covalent bonds are shared and therefore "belong" to both of the bonded atoms. Selenium is a nonmetal in group 6A , and therefore has 6 valence electrons. In order to obey the octet rule, it needs to gain 2 electrons. It can do this by forming 2 single covalent bonds.
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Which of the following constitutes a covalent bond?
Which of the following constitutes a covalent bond?
A chemical bond is considered covalent if there is sharing of one or more pairs of electrons between atoms. As opposed to a covalent bond, an ionic bond can involve the transfer of electrons from one atom to another resulting in a high charge differential between two atoms in order for them to acquire a full octet.
As described by the Pauli Exclusion Principle, every pair of electrons must consist of spin-up paired with spin-down. It states that no more than two electrons may occupy an orbital, and in full electron orbitals, the spin of one must cancel the spin of the other so their spins will have a zero net spin/angular momentum.
Chemical bonds are made up of orbitals, which are simply waves that have wave functions. Wave functions tell us the likelihood that an electron can be found within an orbital. Constructive interference of two wave functions/orbitals occur when the two waves are in phase and result in a new wave function, or in other words a chemical bond.
A chemical bond is considered covalent if there is sharing of one or more pairs of electrons between atoms. As opposed to a covalent bond, an ionic bond can involve the transfer of electrons from one atom to another resulting in a high charge differential between two atoms in order for them to acquire a full octet.
As described by the Pauli Exclusion Principle, every pair of electrons must consist of spin-up paired with spin-down. It states that no more than two electrons may occupy an orbital, and in full electron orbitals, the spin of one must cancel the spin of the other so their spins will have a zero net spin/angular momentum.
Chemical bonds are made up of orbitals, which are simply waves that have wave functions. Wave functions tell us the likelihood that an electron can be found within an orbital. Constructive interference of two wave functions/orbitals occur when the two waves are in phase and result in a new wave function, or in other words a chemical bond.
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Microwave radiation falls in the wavelength region of 
.
What is the frequency of microwave radiation that has a wavelength of 
?
Microwave radiation falls in the wavelength region of
What is the frequency of microwave radiation that has a wavelength of
, where 
is the speed of light, 
is the wavelength, and 
is frequency.
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The wavelength of a particular color of red-orange light is 
.
What is the frequency of this color?
The wavelength of a particular color of red-orange light is
What is the frequency of this color?
, where 
is the speed of light, 
is the wavelength, and 
is frequency.
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What is the frequency of microwave radiation that has a wavelength of 0.885m?
What is the frequency of microwave radiation that has a wavelength of 0.885m?
To solve this problem, we use the following equation:
Where 
is the wavelength and 
is the frequency.
Wavelength is given, and as we are dealing with the electromagnetic spectrum, we know that 
is equal to the speed of light, which is given. We need to solve for frequency, so we arrange the equation as follows: 
Plug in known values and solve.
To solve this problem, we use the following equation:
Where
Wavelength is given, and as we are dealing with the electromagnetic spectrum, we know that
Plug in known values and solve.
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The wavelength of a particular color of orange light is 629nm.
What is the frequency of this color?
The wavelength of a particular color of orange light is 629nm.
What is the frequency of this color?
To solve this problem, we use the following equation:
Where is the wavelength and is the frequency.
Wavelength is given, and as we are dealing with the electromagnetic spectrum, we know that is equal to the speed of light, which is given. We need to solve for frequency, so we arrange the equation as follows: 
Plug in known values and solve.
To solve this problem, we use the following equation:
Where
Wavelength is given, and as we are dealing with the electromagnetic spectrum, we know that
Plug in known values and solve.
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A local FM radio station broadcasts at a frequency of 99.0MHz.
What is the wavelength at which the station is broadcasting?
A local FM radio station broadcasts at a frequency of 99.0MHz.
What is the wavelength at which the station is broadcasting?
To solve this problem, we use the following equation:
Where is the wavelength and is the frequency.
Rearrange the equation to solve for wavelength.
Plug in known values and solve.
To solve this problem, we use the following equation:
Where
Rearrange the equation to solve for wavelength.
Plug in known values and solve.
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A researcher analyzes two types of electromagnetic waves. He observes that wave A has a higher amplitude than wave B. What can you conclude about these two waves?
A researcher analyzes two types of electromagnetic waves. He observes that wave A has a higher amplitude than wave B. What can you conclude about these two waves?
Amplitude of a wave is defined as the maximum peak of oscillation or vibration. Recall that frequency, wavelength, and speed are not dependent on the amplitude and are calculated using the wave equation:
Here, 
is the speed of the wave (which is the speed of light for electromagnetic waves), 
is the frequency, and 
is the wavelength. Amplitude of a wave is not present in this equation and, therefore, cannot be used to determine relative values of frequency, wavelength, and speed.
Amplitude of a wave is defined as the maximum peak of oscillation or vibration. Recall that frequency, wavelength, and speed are not dependent on the amplitude and are calculated using the wave equation:
Here,
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If a star approaches earth the electromagnetic waves from the star are perceived to have shorter wavelength whereas if a star moves away from the earth the waves have longer wavelength.
When observing through a telescope, a scientist notices that star A appears red whereas star B appears blue. Which of the following is true regarding these two stars?
If a star approaches earth the electromagnetic waves from the star are perceived to have shorter wavelength whereas if a star moves away from the earth the waves have longer wavelength.
When observing through a telescope, a scientist notices that star A appears red whereas star B appears blue. Which of the following is true regarding these two stars?
The phenomenon described in this question is called redshift and blueshift. All stars emit electromagnetic waves. The perceived wavelength of these waves depends on the relative motion of the object. If an object is approaching the observer (in this case, the earth) then the apparent wavelength of emitted waves decreases whereas if the object moves away then the apparent wavelength increases. This is called the Doppler effect.
To answer this question, we need to know the relative wavelengths of blue and red light. Blue light has wavelength between 
whereas red light has wavelength between 
. The question states that star A appears red and star B appears blue. Since red has the higher wavelength, star A is going away from the earth. Similarly, since blue has a lower wavelength, star B is approaching earth.
Recall that lower wavelength means higher frequency; therefore, blue has the higher frequency.
The phenomenon described in this question is called redshift and blueshift. All stars emit electromagnetic waves. The perceived wavelength of these waves depends on the relative motion of the object. If an object is approaching the observer (in this case, the earth) then the apparent wavelength of emitted waves decreases whereas if the object moves away then the apparent wavelength increases. This is called the Doppler effect.
To answer this question, we need to know the relative wavelengths of blue and red light. Blue light has wavelength between
Recall that lower wavelength means higher frequency; therefore, blue has the higher frequency.
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Microwave rays have a __________ wavelength and a __________ energy than ultraviolet rays.
Microwave rays have a __________ wavelength and a __________ energy than ultraviolet rays.
To solve this question, we need to first recall the electromagnetic spectrum. Microwaves have very large wavelengths. They are found between visible light and radio waves. Ultraviolet, on the other hand, is found below visible light; therefore, ultraviolet rays have smaller wavelength than microwaves.
To solve for energy we need to use the following equation.
Here, 
is the energy, 
is Planck’s constant, 
is speed of light, and 
is wavelength. Since energy is inversely proportional to wavelength, higher wavelengths will lead to lower energy. This means that microwaves will have lower energy than ultraviolet rays.
Gamma rays have the lowest wavelength and highest energy whereas radio waves typically have the highest wavelength and lowest energy.
To solve this question, we need to first recall the electromagnetic spectrum. Microwaves have very large wavelengths. They are found between visible light and radio waves. Ultraviolet, on the other hand, is found below visible light; therefore, ultraviolet rays have smaller wavelength than microwaves.
To solve for energy we need to use the following equation.
Here,
Gamma rays have the lowest wavelength and highest energy whereas radio waves typically have the highest wavelength and lowest energy.
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Two light sources are placed equidistant from a detector. The light from light source A is detected quicker than light from light source B. What can be concluded from these results?
Two light sources are placed equidistant from a detector. The light from light source A is detected quicker than light from light source B. What can be concluded from these results?
The question states that there are two light sources and that both are placed equidistant from a detector. This means that any differences in detection speed is not related to the distance. The question also states that the detector picks up light from source A quicker that light from source B. This means that the speed of the light from source A is faster. Recall that light (or electromagnetic rays) can have varying wavelengths and frequencies; however, the speed of all electromagnetic rays is the same. It doesn’t matter if it is gamma rays or visible light, the speed of light in air is 
. The information given in this question contradicts this; therefore, these results are invalid.
We cannot determine the color of the light for the light sources because we don't have any information regarding their respective wavelength or frequency. The number of photons per unit time refers to the amplitude of the wave, which also cannot be determined from the given information.
The question states that there are two light sources and that both are placed equidistant from a detector. This means that any differences in detection speed is not related to the distance. The question also states that the detector picks up light from source A quicker that light from source B. This means that the speed of the light from source A is faster. Recall that light (or electromagnetic rays) can have varying wavelengths and frequencies; however, the speed of all electromagnetic rays is the same. It doesn’t matter if it is gamma rays or visible light, the speed of light in air is
We cannot determine the color of the light for the light sources because we don't have any information regarding their respective wavelength or frequency. The number of photons per unit time refers to the amplitude of the wave, which also cannot be determined from the given information.
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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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