Physics Chapter on Quantum Mechanics
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Questions and Answers

What is the wavelength in meters of radio waves used for cellular signals at a frequency of 850 MHz?

  • 0.412 m
  • 0.738 m
  • 0.567 m
  • 0.353 m (correct)

What does Planck's equation, E = hν, represent?

  • The relationship between mass and energy
  • The relationship between temperature and energy
  • The relationship between energy and frequency (correct)
  • The relationship between wavelength and frequency

What happens when electrons return to their normal energy level?

  • They become heavier
  • They freeze
  • They emit a photon of EM radiation (correct)
  • They absorb energy

Why do heated materials emit light according to Planck's postulate?

<p>Because their atoms vibrate at high frequencies (A)</p> Signup and view all the answers

What is a significant characteristic of line spectra emitted by elements?

<p>They show intense lines at certain wavelengths (C)</p> Signup and view all the answers

What is required for the photoelectric effect to occur?

<p>A specific threshold frequency of light (C)</p> Signup and view all the answers

Why is quantization of energy hard to notice on a macroscopic scale?

<p>Because the value of h is very small (D)</p> Signup and view all the answers

What is the primary effect of heating a sample of an element?

<p>It emits electromagnetic radiation (A)</p> Signup and view all the answers

What does the transition of an electron from n = 4 to n = 6 signify?

<p>The electron is in an excited state. (C), The electron is gaining energy. (D)</p> Signup and view all the answers

What indicates that a photon has entered the system during the electron transition?

<p>The energy difference is positive. (C)</p> Signup and view all the answers

In which energy state is the electron before moving to the n = 6 orbit?

<p>n = 4 (C)</p> Signup and view all the answers

What part of the electromagnetic spectrum is associated with the transition of an electron from n = 4 to n = 6?

<p>Ultraviolet radiation (B)</p> Signup and view all the answers

Which of the following correctly describes the nature of the photon during the electron transition?

<p>It is absorbed by the electron. (B)</p> Signup and view all the answers

If the energy difference between the orbits is represented as ΔE, what can be inferred if ΔE is equal to zero?

<p>The electron remains in the same orbit. (C)</p> Signup and view all the answers

What relationship does the quantum number n have with the energy of the electron?

<p>Higher values of n correspond to higher energy. (A)</p> Signup and view all the answers

Which statement about the electron's movement during the transition is true?

<p>It requires energy absorption. (B)</p> Signup and view all the answers

What is the maximum number of electrons that can occupy the f subshell?

<p>14 (D)</p> Signup and view all the answers

According to the Aufbau Principle, how should electrons be filled into orbitals?

<p>From the lowest energy on up (B)</p> Signup and view all the answers

What does Hund’s rule state regarding the arrangement of electrons in orbitals?

<p>All electrons must occupy different orbitals before pairing occurs (A)</p> Signup and view all the answers

What is the full electron configuration of sulfur (S)?

<p>1s2 2s2 2p6 3s2 3p4 (C)</p> Signup and view all the answers

Which energy level has the highest total number of electrons that can be held?

<p>Energy level 4 (B)</p> Signup and view all the answers

How many orbitals are present in the d subshell?

<p>5 (D)</p> Signup and view all the answers

Which electrons are referred to as valence electrons?

<p>Electrons in the outermost shell (highest value of n) (C)</p> Signup and view all the answers

What is the significance of the different energies of orbitals in different subshells?

<p>They dictate the filling order of the orbitals (C)</p> Signup and view all the answers

Why does oxygen have a lower first ionization energy compared to nitrogen?

<p>Oxygen has paired electrons causing repulsion. (C)</p> Signup and view all the answers

What trend is observed in successive ionization energies for elements?

<p>They increase with each successive removal. (A)</p> Signup and view all the answers

What happens to the frequency of a wave as its wavelength increases?

<p>The frequency decreases. (A)</p> Signup and view all the answers

What happens at the stage of large increase in successive ionization energy?

<p>Core electrons are being removed. (B)</p> Signup and view all the answers

How does the electron affinity (EA) of an element influence its ability to accept an electron?

<p>Higher EA indicates an easier acceptance of electrons. (B)</p> Signup and view all the answers

What is the speed of electromagnetic radiation in a vacuum?

<p>$3.0 × 10^8$ m/s (A)</p> Signup and view all the answers

Which of the following statements about wavelength and frequency is true?

<p>Long wavelengths correspond to low frequencies. (D)</p> Signup and view all the answers

What distinguishes endothermic from exothermic processes in electron affinity?

<p>Endothermic processes require energy for electron attachment. (C)</p> Signup and view all the answers

Which of the following elements likely has the lowest first ionization energy based on trends?

<p>Calcium (Ca) (A)</p> Signup and view all the answers

What defines the amplitude of a wave?

<p>One-half the height of the wave from peak to trough. (C)</p> Signup and view all the answers

Which portion of the electromagnetic spectrum has the highest frequency?

<p>X-rays (C)</p> Signup and view all the answers

What characterizes the ionization energy of a cation compared to a neutral atom?

<p>It is more difficult to remove an electron from a cation. (A)</p> Signup and view all the answers

What is the general effect of increasing positive charge on ionization energy?

<p>It increases the ionization energy. (A)</p> Signup and view all the answers

What is true about the various colors of visible light?

<p>Each color has specific frequencies and wavelengths associated with them. (B)</p> Signup and view all the answers

What does the product of a wave’s wavelength and frequency equal?

<p>Speed of the wave (B)</p> Signup and view all the answers

In which way does the electromagnetic spectrum represent different types of EM radiation?

<p>By increasing wavelength and decreasing frequency. (B)</p> Signup and view all the answers

What is the wavelength of light given off by a sodium streetlight in meters?

<p>589 x $10^{-9}$ m (A)</p> Signup and view all the answers

Which formula is used to calculate frequency from wavelength?

<p>ν = c / λ (D)</p> Signup and view all the answers

What unit is commonly used to express the frequency of radio waves?

<p>Hertz (Hz) (B)</p> Signup and view all the answers

In determining the frequency of radiation, what must be done first with the wavelength?

<p>Convert it to meters. (C)</p> Signup and view all the answers

If the speed of light is approximately $3 x 10^8$ m/s, what is the frequency of light with a wavelength of 589 nm?

<p>5.10 x $10^{14}$ Hz (D)</p> Signup and view all the answers

What is the frequency of the cellular signal that operates at 850 MHz in Hertz?

<p>850 x $10^{6}$ Hz (C)</p> Signup and view all the answers

What is the speed of light commonly represented as in scientific calculations?

<p>3.00 x $10^8$ m/s (A)</p> Signup and view all the answers

What is the primary purpose of knowing the frequency and wavelength of electromagnetic radiation?

<p>To understand communication technologies. (C)</p> Signup and view all the answers

Flashcards

Wavelength (λ)

The distance between two consecutive peaks or troughs of a wave.

Frequency (ν)

The number of wave cycles that pass a given point per second.

Amplitude

One-half the distance between the peaks and troughs of a wave.

Electromagnetic (EM) Radiation

Energy that travels through space as waves.

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Speed of a wave

The product of a wave's wavelength and its frequency.

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Speed of Light

3.0 x 108 meters per second is the speed of EM radiation in a vacuum. This constant is represented by 'c'.

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Inverse Proportionality

The relationship between wavelength and frequency, where increasing wavelength corresponds to decreasing frequency.

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Electromagnetic Spectrum

The range of all types of electromagnetic radiation.

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Speed of Light (c)

The speed at which light travels in a vacuum, approximately 299,792,458 meters per second.

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Equation for Light Waves

The relationship between the speed of light, wavelength, and frequency is described by the equation c = λν, where c is the speed of light, λ is the wavelength, and ν is the frequency.

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Converting Nanometers to Meters

To convert nanometers (nm) to meters (m), divide by 1 billion (10^9).

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Megahertz (MHz)

A unit of measurement for frequency, equal to one million cycles per second. (1 MHz = 1,000,000 Hz)

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Rearranging Equations

The process of rearranging an equation to solve for a specific variable. For example, if you have c = λν and want to solve for ν, you would rearrange the equation to get ν = c / λ.

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Electromagnetic Wave

A wave that carries electromagnetic radiation, including visible light, radio waves, microwaves, and X-rays. The frequency and wavelength determine the type of electromagnetic radiation.

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Atomic Spectra

The unique pattern of wavelengths of light emitted by an excited atom.

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Planck's Quantum Postulate

The energy of a photon is quantized, meaning it can only exist in discrete packets called quanta. Each quanta has an energy of hν, where h is Planck's constant and ν is the frequency of the light.

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Planck's Equation

The energy of a photon is proportional to its frequency (and inversely proportional to its wavelength).

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Photoelectric Effect

The phenomenon where electrons are ejected from a metal surface when light of sufficiently high frequency shines on it.

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Threshold Frequency

The minimum frequency of light required to eject electrons from a metal surface in the photoelectric effect.

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Work Function

The energy required to remove an electron from a metal surface.

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Energy Level Transition

The energy difference between two energy levels in an atom.

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Photon Emission

The process of an atom emitting a photon when an electron transitions from a higher energy level to a lower energy level.

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Atomic orbitals

Three-dimensional shapes representing the probable location of an electron in an atom.

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Orbital energy

Different subshells have distinct energy levels, while orbitals within the same subshell have equal energies.

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Aufbau Principle

Electrons fill atomic orbitals starting from the lowest energy level and moving upwards.

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Hund's rule

For degenerate orbitals (equal energy), each orbital gets one electron before any pairing occurs.

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Electron Configuration

A concise notation representing the distribution of electrons within atomic orbitals.

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Valence Electrons

Electrons in the outermost shell (highest 'n' value) are involved in chemical bonding.

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Core Electrons

Electrons residing in inner shells (lower 'n' values) are not directly involved in bonding.

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Orbital Diagram

A visual representation of the electron configuration, showing individual orbitals and electron pairing.

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First Ionization Energy (IE1)

The energy required to remove one electron from a neutral gaseous atom in its ground state.

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Second Ionization Energy (IE2)

The energy required to remove an electron from a positively charged ion in its ground state.

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Ionization Energy Trend Across a Period

The ionization energy generally increases as you move across a period from left to right due to increasing nuclear charge and a smaller atomic radius.

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Ionization Energy Trend Down a Group

The ionization energy generally decreases as you move down a group due to increasing atomic radius and shielding effect.

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Deviation in Ionization Energy: Oxygen vs. Nitrogen

Oxygen has a lower IE1 than nitrogen because removing an electron from oxygen eliminates electron-electron repulsion in the partially filled 2p orbital, making it more energetically favorable.

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Electron Affinity

The energy change that occurs when an electron is added to a gaseous atom to form a negative ion.

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Higher Electron Affinity

A higher negative value of electron affinity indicates that the atom gains an electron more readily, releasing more energy.

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Electron Affinity Trend

The electron affinity values generally increase as you move across a period and decrease as you move down a group. However, there are exceptions.

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Electron Transition

Change in energy levels of an electron within an atom, where the electron moves from a lower energy level (n1) to a higher energy level (n2). This transition requires energy, usually in the form of a photon.

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Electron Relaxation

The movement of an electron from a higher energy level to a lower energy level within an atom. During this process, energy is released, often as a photon of light.

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Energy Difference

The amount by which an electron's energy changes during an electronic transition. It's the difference between initial and final energy levels.

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Energy Difference and Frequency Relationship

The energy difference between two energy levels in an atom is directly proportional to the frequency of the photon emitted or absorbed during the transition.

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Electronic Transition Radiation

The electromagnetic radiation emitted or absorbed during an electron transition from one energy level to another.

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Energy Difference Sign

Indicates the direction of energy flow during an electron transition. Positive energy difference signifies energy absorption, while a negative value indicates energy emission.

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Principle Quantum Number (n)

The principle quantum number (n) describes the energy level of an electron in an atom. Higher n values indicate higher energy levels.

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Bohr Orbit

The series of energy levels available to electrons in an atom, often characterized by their principle quantum numbers (n=1, 2, 3, etc.).

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