Chapter 5 - Electrons In Atoms - Test
When did Niels Bohr make his discovery?
1913.
What is the correct electron configuration of a sulfur atom?q
1s2 2s2 2p6 3s2 3p4.
What is the formula for the maximum number of electrons that can occupy a principal energy level/
2N2.
What does each possible electron orbit in Bohr's model have?
A fixed energy.
What did Schrödinger devise?
A mathematical equation that described the behavior of the electron in a hydrogen atom.
Define atomic orbital.
A mathematical expression describing the probability of finding an electron at various locations; usually represented by the region of space around the nucleus where there is a high probability of finding an electron.
What did Schrödinger's equation lead to for each energy level?
A mathematical expression, called an atomic orbital.
Define spin.
A quantum mechanical property of electrons that may be thought of as clockwise of counterclockwise.
Define photon.
A quantum of light; a discrete bundle of electromagnetic energy that interacts with matter similarly to particles.
What is an atomic orbital represented pictorially as?
A region of space in which there is a high probability of finding an electron.
What is an atomic orbital?
A region of space in which there is a high probability of finding an electron.
Define Pauli exclusion principle.
An atomic orbital may describe at most two electrons, each with opposite spin direction.
What did Bohr propose in his model of the atom?
Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus.
How are the energy levels of electrons in the quantum mechanical model labeled?
By principal quantum numbers (n).
How does quantum mechanics differ from classical mechanics?
Classical mechanics adequately describes the motions of bodies much larger than atoms, while quantum mechanics describes the motions of subatomic particles and atoms as waves.
What did the quantum mechanical model do that was not similar to Bohr's model?
Did not specify an exact path the electron takes around the nucleus.
What shape is the P orbital?
Dumbbell shaped.
How do sublevels of principal energy levels differ?
Each energy sublevel corresponds to one or more orbitals of different shapes. The orbitals describe where an electron is likely to be found.
What is the maximum number of electrons energy level two can hold?
Eight.
What is the maximum number of electrons energy level three can hold?
Eighteen.
Define Hund's rule.
Electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible.
Define electromagnetic radiation.
Energy waves that travel in a vacuum at a speed of 2.998 x 108 m/s; includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays.
How many orbitals does energy level three have?
Five.
How many sub-levels does energy level four have?
Four.
What did Niels Bohr change from Rutherford's model?
He changed Rutherford's model to incorporate newer discoveries about how the energy of an atom changes when the atom absorbs or emits.
Define amplitude.
Height of a wave crest.
What does probability describe?
How likely it is to find an electron in a particular location around the nucleus.
What were the limitations of Rutherford's atomic model?
It explained only a few simple properties of atoms and it could not explain the chemical properties of elements.
Define Heisenberg uncertainty principle.
It is impossible to know both the velocity and position of an electron at the same time.
What are different atomic orbitals denoted by?
Letters.
How are the quantum mechanical model and the Bohr model alike? How are they different?
Like the Bohr model, the quantum mechanical model restricts the energy of electrons to certain values. Unlike the Bohr model, the quantum mechanical model does not specify an exact path the electron takes around the nucleus.
What is the equation to find the number of orbitals in a principal energy level?
N2.
What does each energy sub-level correspond to?
One or more orbitals of different shapes, which describe where the electron is likely to be found.
How many orbitals does energy level one have?
One.
How many sub-levels does energy level one have?
One.
What were previous models of the atom?
Physical models that were based on the motion of large objects.
What did the quantum mechanical model do that was similar to Bohr's model?
Restricted the energy of electrons to certain values.
What letters represent energy level four?
S, P, D, and F.
What letters represent energy level three?
S, P, D.
What letters represent energy level two?
S, P.
What letter represents energy level one?
S.
How many orbitals does energy level four have?
Seven.
What does each principal energy level greater than 1 have?
Several orbitals with different shapes and different energy levels.
What shape is the S orbital?
Spherical.
What did Bohr propose?
That an electron is found only in specific circular paths, or orbits, around the nucleus.
How does the Bohr model improve upon the Rutherford model?
The Rutherford model could not explain why elements that have been heated to higher and higher temperatures give off different colors of light. The Bohr model explains how the energy levels of electrons in an atom change when the atom emits light.
What does the quantum mechanical model determine?
The allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus of an atom.
Define quantum.
The amount of energy needed to move an electron from one energy level to another.
What is a quantum?
The amount of energy required to move an electron from one energy level to another energy level.
Define electron configuration.
The arrangement of electrons of an atom in its ground state into various orbitals around the nuclei of atoms.
Define Planck's constant.
The constant by which the amount of radiant energy is proportional to the frequency of the ration.
Define wavelength.
The distance between two corresponding parts of a wave.
What happens to the electrons that move to higher levels when atoms absorb energy?
The electrons lose their energy by emitting light when they return to a lower energy level.
What does the solutions to Schrödinger's equations give?
The energies an electron can have and the atomic orbitals, which describe the regions of space where an electron may be found.
What do the solutions to Schrödinger's equations give?
The energies, or the energy levels, an electron can have.
What does the light emitted by an electron moving from a higher to a lower energy level has a frequency directly proportional to?
The energy change of the electron.
Why is the rungs on a ladder compared to Bohr's model of the atom?
The energy levels in atoms are unequally spaced, like the rungs in this unusual ladder. The higher energy levels are closer together.
What are energy levels?
The fixed energies an electron can have
How are the frequencies of light emitted by an atom related to changes of electron energies?
The light emitted by an electron moving from a higher to lower energy level has a frequency directly proportional to the energy changes of the electron.
Define ground state.
The lowest possible energy of an atom described by quantum mechanics.
What did the quantum mechanical model come from?
The mathematical solutions of Schrödinger's equation.
Calculate the maximum number of electrons in the 5th principal energy level (n = 5).
The maximum number of electrons that can occupy a principal energy level is given by the formula 2N2. If n = 5, 2N2 = 50.
Define quantum mechanical model.
The modern description, primarily mathematical, of the behavior of electrons in atoms.
What does classical mechanics adequately describe?
The motions of bodies much larger than atoms.
What does quantum mechanics describe?
The motions of subatomic particles and atoms as waves.
What does the principal quantum number N always equal?
The number of sub-levels within a certain principal energy level?
Define frequency.
The number of wave cycles that pass a given point per unit of time; frequency and wavelength are inversely proportional to each other.
Define atomic emission spectrum.
The pattern formed when light passes through a prism of diffraction grating to separate it into the different frequencies of light it contains.
Define photoelectric effect.
The phenomenon in which electrons are ejected when light shines on a metal.
What can be represented as a fuzzy, cloud like region in the quantum mechanical model?
The probability of finding an electron within a certain volume of space surrounding the nucleus.
What is the modern description of the electrons in atoms?
The quantum mechanical model
What does the quantum mechanical model determine about the electrons in an atom?
The quantum mechanical model determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus of an atom.
What was the result of Schrödinger's solutions?
The quantum mechanical model.
Define aufbau principle.
The rule that electrons occupy the orbitals of lowest energy first.
What object is compared to Bohr's model of the atom?
The rungs on a ladder.
What does the quantum mechanical model come from?
The solutions to Schrödinger's equation.
Define energy level.
The specific energies an electron in an atom or other system can have.
Define hertz.
The unit of frequency, equal to one cycle per second.
What happens when atoms absorb energy?
Their electrons move to higher energy levels.
What did Austrian physicist Erwin Schrödinger use?
Theoretical calculations and experimental results.
What is the maximum number of electrons energy level four can hold?
Thirty-two.
What are the three rules for writing configurations of elements?
Three rules—the aufbau principle, the Pauli exclusion principle, and Hund's rule—tell you how to find the electron configurations of atoms.
How many orbitals does energy level two have?
Three.
How many sub-levels does energy level three have?
Three.
Why did Erwin Schrödinger use theoretical calculation and experimental results?
To devise and solve a mathematical equation describing the behavior of electron in a hydrogen atom.
How did Einstein explain the photoelectric effect?
To explain the photoelectric effect, Einstein proposed that light could be described as quanta of energy that behave as if they were particles.
What is the maximum number of electrons that can occupy an orbital?
Two electrons.
How many sub-levels does energy level two have?
Two.
What is the maximum number of electrons energy level one can hold?
Two.
The Heisenberg uncertainty principle states that it is impossible to simultaneously know which two attributes of a particle?
Velocity and position.
Define spectrum.
Wavelengths of visible light that are separated when a beam of light passes through a prism; range of wavelengths of electromagnetic radiation.
What causes atomic emission spectra?
When atoms absorb energy, their electrons move to higher energy levels. These electrons lose energy by emitting light when they return to lower energy levels.
When is the fuzzy, cloud like region in the quantum mechanical model more dense?
When the probability of finding electrons is more high.