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Slide 1 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light How are the wavelength and frequency of light related? 5.3

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Slide 2 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light The amplitude of a wave is the waves height from zero to the crest. The wavelength, represented by (the Greek letter lambda), is the distance between the crests. 5.3

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Slide 3 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light The amplitude of a wave is the waves height from zero to the crest. The wavelength, represented by (the Greek letter lambda), is the distance between the crests. 5.3

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Slide 4 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light The frequency, represented by (the Greek letter nu), is the number of wave cycles to pass a given point per unit of time. The SI unit of cycles per second is called a hertz (Hz). 5.3

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Slide 5 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light The frequency, represented by (the Greek letter nu), is the number of wave cycles to pass a given point per unit of time. The SI unit of cycles per second is called a hertz (Hz). 5.3

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Slide 6 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light The wavelength and frequency of light are inversely proportional to each other. 5.3

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Slide 7 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light The product of the frequency and wavelength always equals a constant (c), the speed of light. 5.3

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Slide 8 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Light According to the wave model, light consists of electromagnetic waves. Electromagnetic radiation includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. All electromagnetic waves travel in a vacuum at a speed of 2.998 10 8 m/s. 5.3

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© Copyright Pearson Prentice Hall Models of the Atom > Slide 9 of 26 The Development of Atomic Models 5.1

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Slide 10 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Development of Atomic Models Rutherfords atomic model could not explain the chemical properties of elements. Rutherfords atomic model could not explain why objects change color when heated. 5.1

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Slide 11 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Development of Atomic Models The timeline shoes the development of atomic models from 1803 to 1911. 5.1

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© Copyright Pearson Prentice Hall Models of the Atom > Slide 12 of 26 The Bohr Model What was the new proposal in the Bohr model of the atom? 5.1

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© Copyright Pearson Prentice Hall Slide 13 of 26 Models of the Atom > The Bohr Model Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus. 5.1

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Slide 14 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Bohr Model Each possible electron orbit in Bohrs model has a fixed energy. The fixed energies an electron can have are called energy levels. A quantum of energy is the amount of energy required to move an electron from one energy level to another energy level. 5.1

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Slide 15 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Bohr Model Like the rungs of the strange ladder, the energy levels in an atom are not equally spaced. The higher the energy level occupied by an electron, the less energy it takes to move from that energy level to the next higher energy level. 5.1

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Slide 16 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Development of Atomic Models The timeline shows the development of atomic models from 1913 to 1932. 5.1

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Slide 17 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Spectra What causes atomic emission spectra? 5.3

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Slide 18 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Spectra When atoms absorb energy, electrons move into higher energy levels. These electrons then lose energy by emitting light when they return to lower energy levels. 5.3

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Slide 19 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Physics and the Quantum Mechanical Model Neon advertising signs are formed from glass tubes bent in various shapes. An electric current passing through the gas in each glass tube makes the gas glow with its own characteristic color. You will learn why each gas glows with a specific color of light. 5.3

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Slide 20 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Spectra A prism separates light into the colors it contains. When white light passes through a prism, it produces a rainbow of colors. 5.3

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Slide 21 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Spectra When light from a helium lamp passes through a prism, discrete lines are produced. 5.3

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Slide 22 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Spectra The frequencies of light emitted by an element separate into discrete lines to give the atomic emission spectrum of the element. 5.3 Mercury Nitrogen

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Slide 23 of 26 © Copyright Pearson Prentice Hall Models of the Atom > An Explanation of Atomic Spectra How are the frequencies of light an atom emits related to changes of electron energies? 5.3

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Slide 24 of 26 © Copyright Pearson Prentice Hall Models of the Atom > An Explanation of Atomic Spectra In the Bohr model, the lone electron in the hydrogen atom can have only certain specific energies. When the electron has its lowest possible energy, the atom is in its ground state. Excitation of the electron by absorbing energy raises the atom from the ground state to an excited state. A quantum of energy in the form of light is emitted when the electron drops back to a lower energy level. 5.3

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Slide 25 of 26 © Copyright Pearson Prentice Hall Models of the Atom > An Explanation of Atomic Spectra 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. 5.3

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Slide 26 of 26 © Copyright Pearson Prentice Hall Models of the Atom > An Explanation of Atomic Spectra The three groups of lines in the hydrogen spectrum correspond to the transition of electrons from higher energy levels to lower energy levels. 5.3

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Slide 27 of 26 © Copyright Pearson Prentice Hall Models of the Atom > An Explanation of Atomic Spectra Animation 6 Learn about atomic emission spectra and how neon lights work.

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Slide 28 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Quantum Mechanics How does quantum mechanics differ from classical mechanics? 5.3

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Slide 29 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Quantum Mechanics In 1905, Albert Einstein successfully explained experimental data by proposing that light could be described as quanta of energy. The quanta behave as if they were particles. Light quanta are called photons. In 1924, De Broglie developed an equation that predicts that all moving objects have wavelike behavior. 5.3

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Slide 30 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Quantum Mechanics Today, the wavelike properties of beams of electrons are useful in magnifying objects. The electrons in an electron microscope have much smaller wavelengths than visible light. This allows a much clearer enlarged image of a very small object, such as this mite. 5.3

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Slide 31 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Quantum Mechanics Simulation 4 Simulate the photoelectric effect. Observe the results as a function of radiation frequency and intensity.

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Slide 32 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Quantum 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. 5.3

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Slide 33 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Quantum Mechanics The Heisenberg uncertainty principle states that it is impossible to know exactly both the velocity and the position of a particle at the same time. This limitation is critical in dealing with small particles such as electrons. This limitation does not matter for ordinary- sized object such as cars or airplanes. 5.3

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Slide 34 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Quantum Mechanics The Heisenberg Uncertainty Principle 5.3

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© Copyright Pearson Prentice Hall Models of the Atom > Slide 35 of 26 The Quantum Mechanical Model What does the quantum mechanical model determine about the electrons in an atom? 5.1

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© Copyright Pearson Prentice Hall Slide 36 of 26 Models of the Atom > The Quantum Mechanical Model 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. 5.1

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Slide 37 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Quantum Mechanical Model Austrian physicist Erwin Schrödinger (1887– 1961) used new theoretical calculations and results to devise and solve a mathematical equation describing the behavior of the electron in a hydrogen atom. The modern description of the electrons in atoms, the quantum mechanical model, comes from the mathematical solutions to the Schrödinger equation. 5.1

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Slide 38 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Quantum Mechanical Model The propeller blade has the same probability of being anywhere in the blurry region, but you cannot tell its location at any instant. The electron cloud of an atom can be compared to a spinning airplane propeller. 5.1

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Slide 39 of 26 © Copyright Pearson Prentice Hall Models of the Atom > The Quantum Mechanical Model In the quantum mechanical model, the probability of finding an electron within a certain volume of space surrounding the nucleus can be represented as a fuzzy cloud. The cloud is more dense where the probability of finding the electron is high. 5.1

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© Copyright Pearson Prentice Hall Models of the Atom > Slide 40 of 26 Atomic Orbitals How do sublevels of principal energy levels differ? 5.1

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Slide 41 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Orbitals An atomic orbital is often thought of as a region of space in which there is a high probability of finding an electron. Each energy sublevel corresponds to an orbital of a different shape, which describes where the electron is likely to be found. 5.1

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Slide 42 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Orbitals Different atomic orbitals are denoted by letters. The s orbitals are spherical, and p orbitals are dumbbell-shaped. 5.1

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Slide 43 of 26 © Copyright Pearson Prentice Hall Models of the Atom > Atomic Orbitals Four of the five d orbitals have the same shape but different orientations in space. 5.1

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© Copyright Pearson Prentice Hall Slide 44 of 26 Models of the Atom > The Development of Atomic Models The timeline shows the development of atomic models from 1913 to 1932. 5.1

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