Week 10 SB
Which of the following wave properties are related to the amplitude of an electromagnetic wave? Select all that apply.
Intensity Brightness (for visible light)
Which of the following statements correctly describe a photon? Select all that apply.
Matter cannot absorb or emit a fraction of a photon. A photon is a particle of electromagnetic radiation.
Which of the following correctly define, depict the symbol, and provide the units for the speed of electromagnetic radiation (light)? Select all that apply.
c = 3.00 × 108 m/s c = λ × υ Light moves at a constant distance per time.
The _____ of a wave is the number of wave cycles per second. This quantity is given the symbol ν and has units of s-1 or _____.
frequency; Hz
Which of the following statements correctly describe the principal quantum number, n? Select all that apply.
n can have any positive whole-number value. The lower the value of n, the greater the probability that the electron is closer to the nucleus.
Which of the following statements correctly describe wave-particle duality? Select all that apply.
All matter exhibits wavelike motion. Matter and energy are different forms of the same entity. Energy and mass can be interconverted.
Which of the following statements correctly describe the angular momentum quantum number, l? Select all that apply.
The number of possible l values equals the value of n. The value of l dictates the allowed values of ml . The allowed values of l are determined by the value of n.
Which of the following statements correctly describe probability density and electron probability density diagrams? Select all that apply.
The probability of finding an electron generally decreases with increasing distance from the nucleus. These diagrams show the probability of finding an electron in a particular region of the atom.
Select all the options that correctly describe the radial probability distribution plot of the electron in the ground-state hydrogen atom.
The radial probability distribution plot is the total probability of finding the electron as a function of distance from the nucleus. The radial probability distribution plot indicates the most probable distance from the nucleus in which to find the electron. The radial probability distribution plot is the sum of Ψ2 values of spherical layers surrounding the nucleus.
Which of the following statements correctly describe the information provided by quantum numbers? Select all that apply.
The relative size of the orbital is indicated by the value of n. The quantum number l indicates the shape of an orbital. The quantum number n indicates the principal energy level of an orbital.
In Bohr's model of the atom, the quantum number n is associated with the _____ of an electron orbit. The lower the n value, the _____ the electron is to/from the nucleus and the _____ the energy level.
energy; closer; lower
The speed of a wave is determined by multiplying the___of the wave by its wavelength. In a vacuum all electromagnetic radiation travels at a constant speed, the speed of___ , which is equal to 3.00 x 108 m/s. (Include a word in the last fill in the blank space, not a number.)
frequency light
An atom is in its lowest energy state, or _____ state, when its electrons are in the lowest possible energy levels. If an electron in the atom absorbs a photon of radiation that is equal in energy to the difference between two energy states, it will move to a higher energy state and the atom is said to be in the _____ state.
ground; excited
according to the Bohr model for the hydrogen atom, the energy of the atom is not continuous but has certain discrete energy___ , each of which is related to a fixed circular ___of the electron around the nucleus. The farther the electron is from the nucleus, the___ the energy of the system.
levels orbit higher
Arrange the following regions of the electromagnetic spectrum in order of increasing frequency: infrared, microwave, gamma, visible.
microwave < infrared < visible < gamma
Light of a single wavelength is termed _____ and light consisting of many wavelengths is termed _____.
monochromatic polychromatic
The energy levels of the hydrogen atom depend on the value of which quantum number(s)?
n
The principal quantum number is given the symbol __ and has positive, whole-number values starting from __ .
n 1
The phenomenon where an electric current is produced by shining a light on a metal plate is called the ___effect. The minimum frequency required to cause a current to flow is called the ___frequency. This frequency depends on the identity of the metal used.
photoelectric threshold
The phenomenon where an electric current is produced by shining a light on a metal plate is called the ___effect. The minimum frequency required to cause a current to flow is called the___ frequency. This frequency depends on the identity of the metal used.
photoelectric threshold
A p orbital has __ regions or lobes of high electron probability on either side of the nucleus. This gives the orbital a dumbbell shape with a(n) __ or region of zero electron density at the nucleus.
two node
The distance a wave travels during one cycle is called its___ . This is usually measured as the distance between two or two___ troughs
wavelength crests
Place the following types of electromagnetic radiation in order of increasing wavelength (shortest at the top to longest at the bottom).
xray uv visible IR radio
Which of the following correctly depict the symbol and units for frequency? Select all that apply.
ν Hz
Energy is quantized. What does this mean?
There is a basic unit of energy that cannot be subdivided further.
Which statement correctly describes the quantum number n with reference to the Bohr model of the hydrogen atom? Select all that apply.
n can have any positive, whole-number value greater than or equal to 1. n indicates the energy level of an electron in the atom. An electron with n = 2 is at higher energy than an electron with n = 1.
Select the frequency of light having a wavelength of 2.4 × 1010 nm and the wavelength of light with a frequency of 2.4 × 1010 Hz. Select all that apply.
1.3 x 107 nm 1.3 × 107 Hz
Which of the following statements correctly describe an s orbital? Select all that apply.
A 2s orbital has two regions of high electron density. An s orbital has a spherical shape.
Which of the following correctly defines an atomic orbital in terms of the quantum-mechanical model of the atom?
A mathematical function that describes the position of the electron-wave in three dimensions
Which of the following statements correctly describe the photoelectric effect? Select all that apply.
Current begins to flow immediately when light of the correct frequency shines on the metal plate. The threshold frequency differs for different metals used in the photoelectric cell.
Which of the following correctly describes the diffraction of light?
Diffraction is the apparent bending of light around the edge of an object in its path.
Which of the following equations correctly reflects the relationship between energy and frequency?
E = hν
Which of the following correctly expresses energy in terms of Planck's constant? Select all that apply.
E = hν E = hc/λ
Which of the following statements correctly describe the electromagnetic spectrum? Select all that apply.
The color of visible light is related to its frequency. All waves in the spectrum travel at the same speed in a vacuum.
Bohr developed an equation for calculating the energy levels of a hydrogen atom. Which of the following can be determined using this equation? Select all that apply.
The energy needed to remove an electron completely from the hydrogen atom The wavelength of a line in the atomic line spectrum for hydrogen The difference in energy between two energy levels in a hydrogen atom
Which of the following statements correctly describes how energy is absorbed by an atom?
The energy of the absorbed radiation must match the difference between the two energy states of the atom.
In a photoelectric diode, no current will flow unless light of a certain minimum threshold frequency is used. Which of the following explains this observation correctly?
The energy of the light photons must match or exceed the energy needed for electrons to break free from the metal.
Which of the following correctly defines the amplitude of a wave?
The height of each crest or depth of each trough
Which of the following statements correctly describe the de Broglie wavelength for a particle? Select all that apply.
The larger the mass of the particle, the smaller its wavelength. Wave behavior is most obvious for very small particles. The smaller the object, the closer the wavelength is to the size of the object.
Why does each element have its own unique atomic line spectrum?
The lines in the spectrum correspond to the differences between the specific energy states in the atom.
Which of the following defines the ground state of an atom?
The lowest energy state of an atom, where all electrons are in the lowest energy levels possible
Which of the following statements correctly describe the limitations of the Rutherford model of the atom? Select all that apply.
This model could not explain observed atomic line spectra. This model could not explain why electrons did not emit energy continuously.
Which of the following determines the color of visible light? Select all that apply.
Wavelength Frequency
What quantities can be calculated from the Bohr equation for the energy levels of the hydrogen atom? Select all that apply. E = -2.18 × 10-18 J (1n2)
We can find the energy needed to ionize the hydrogen atom. We can find the energy change of the electron moving between two levels. We can find the wavelength of a spectral line.
In order for a current to flow in a photoelectric cell, a photon of light must be___ by an electron in the metal. For this to occur, the___ of the photon must be equal to or greater than the energy needed to remove the electron from its energy state. It is the ___of the light that is important, not its intensity.
absorbed energy frequency
The _____ momentum quantum number has the symbol l and can take values from _____ to (n - 1). This number is related to the _____ of the orbital.
angular; 0; shape
Any two waves that meet as they travel through the same medium will interact. If the two waves are in phase their crests will coincide and they will experience _____ interference, producing a wave with a(n) _____ amplitude.
constructive; increased
Using the Schrodinger wave equation, we can determine the probability of finding an electron in a particular region of the atom. The electron probability density _____ with distance from the nucleus, meaning that the farther one gets from the nucleus the _____ likely it is to find an electron. (Electrons are not found within the nucleus.)
decreases; less
Atoms, like all other matter, have specific energy levels within them. For an atom to absorb radiation, the energy of the radiation must match the energy ___ between the two energy levels in the atoms.
difference
The apparent bending of a wave around the edge of an object is called _____. If a wave passes through a slit that has a width of the same order of magnitude as its _____, it will bend around both edges of the slit to give a semicircular wave.
diffraction; wavelength
Radial probability distribution plots show the total probability (the sum within a concentric layer) of finding a(n) __ as a function of distance r from the nucleus.
electron
Each element has its own atomic line spectrum, consisting of fine lines of individual wavelengths that are characteristic for the element. This occurs because the atom contains specific___ levels, and an atom can only absorb or emit radiation that corresponds to the energy___ between these levels.
energy differences
Waves that are in phase: Waves that are out of phase:
experience constructive interference experience destructive
True or false: The atomic orbital of the quantum-mechanical model is very similar to the orbit described by the Bohr model.
f
Amplitudes will add: Amplitudes will cancel:
if waves are in phase if out of phase
Wavelength and frequency are _____ proportional to each other. As wavelength increases, frequency will _____.
inversely; decrease
When describing orbitals, a node ________. Select all that apply.
is a region of zero electron density occurs when ψ2 is equal to zero
Select the correct symbol and units for wavelength. Select all that apply.
nm λ
A region of zero electron density in an orbital is called a(n) ______.
node
Which of the following statements correctly describe p orbitals? Select all that apply.
p orbitals always occur in groups of three. The p orbitals of a group are perpendicular to each other. A p orbital has a dumbbell shape with two lobes, one on either side of the nucleus.
Electrons, like all other matter, exhibit the dual behavior of both __ and waves. Since electrons travel like waves, their energy is restricted to certain energy __ , each of which is associated with a specific wavelength.
particle level
Electromagnetic radiation consists of particles called___ , each of which has a discrete amount, or quantum, of energy. However, since electromagnetic radiation also has wave properties, each particle is also characterized by a specific___ (usually expressed in nm) and frequency (expressed in s-1).
photons wavelength
Heisenberg's uncertainty principle states that it is not possible to know the exact momentum and __ of a particle simultaneously. In terms of atomic structure, this means that we cannot determine fixed __ for electrons but can only determine the __ of finding an electron in a given region of space.
position levels probability
The speed of light is the ______ of its frequency and wavelength. In a vacuum, this value is a constant, ______.
product 33.00*10^8m/s
Energy is not continuous, but is quantized or divided into "packets," each of which contains a definite amount of energy. An energy packet is called a(n) _____, and the energy of each packet is directly proportional to its _____.
quantum frequency
An orbital with l = 0 is called a(n) _____ type orbital and has a(n) _____ shape. There is always a total of _____ orbital(s) of this type for each principal energy level.
s; spherical; 1
All waves in the electromagnetic spectrum travel at the same _____ through a vacuum, but differ in their frequency and wavelength. A wave with a long (large) wavelength will have a _____ frequency.
speed low
Rutherford's nuclear model of the atom cannot exist according to classical physics because charged particles like electrons in orbit around a nucleus would continuously lose energy. The result would be that as electrons lose energy they would ______.
spiral into the nucleus to collapse the atom
True or false: The sublevels of each principal energy level of the hydrogen atom have the same energy.
t
The frequencies and wavelengths of visible light are perceived as different colors. The visible region of the electromagnetic spectrum ranges from higher frequency/shorter wavelength ______ to lower frequency/longer wavelength ______.
violet; red
All matter behaves as though it moves in a(n) __ . The motion of any particle can be described by the de Broglie equation, which relates the wavelength of a particle to its __ and speed.
wave mass
In the quantum-mechanical model of the atom, an electron is viewed as a wave-particle that occupies a three-dimensional space near the nucleus. The movement of the electron is described by a __ function, which is also called an atomic __.
wave orbital
Which of the following statements correctly describe the atom in terms of quantum mechanics? Select all that apply.
Electrons exhibit behavior of both waves and particles. The movement of each electron in the atom can be described by a wave function. Each electron occupies a three-dimensional space near the nucleus. This space is described by a wave function.
Why are electrons restricted to certain, discrete energy levels within an atom?
Electrons have wavelike motion and are restricted to certain energy states associated with specific wavelengths.
Which of the following is a consequence of the Heisenberg uncertainty principle?
It is not possible to assign fixed paths for electrons.
Which of the following statements correctly describe the Bohr model of the hydrogen atom? Select all that apply.
The atom is in its lowest energy state when the electron is in the orbit closest to the nucleus. Only certain energy levels are allowed within the hydrogen atom. Each energy state of the hydrogen atom is associated with a fixed circular orbit of the electron around the nucleus.
Visible light is one type of___ radiation, which consists of energy propagated by electric and___ fields that alternately increase and decrease in intensity as they move through space.
electromagnetic magnetic
Visible light and radio waves are both examples of___ radiation, which has a dual nature, possessing the properties of both___ and waves.
electromagnetic particles
A central concept in quantum mechanics is that both matter and __ are alternate forms of the same entity and therefore both exhibit dual characteristics of particles and of __ . This model allows a better understanding of the behavior of tiny particles such as electrons.
energy waves
