Zumdahl • Zumdahl • DeCoste World of CHEMISTRY

Chapter 11 Modern Atomic Theory

Review Trends in the periodic table: certain elements grouped together because they behave similarly there is great similarities within groups, but the differences in behavior between groups is what we will be studying. Copyright © Houghton Mifflin Company

Objective: To describe Rutherford’s model of the atom 11.1 Rutherford’s Atom Objective: To describe Rutherford’s model of the atom Copyright © Houghton Mifflin Company

Review of the composition of an atom Nucleus Proton (+) Orbital's Electrons (-) Copyright © Houghton Mifflin Company

Figure 11.1: The Rutherford atom. Rutherford’s model shows a very small nucleus with electrons arranged in such a way that he believed they revolved around the nucleus (i.e. like the solar system) What Rutherford could not explain was why the negative electrons aren’t attracted into the positive protons, causing the atom to collapse. Copyright © Houghton Mifflin Company

Objective: To explore the nature of electromagnetic radiation. 11.2 Energy and Light Objective: To explore the nature of electromagnetic radiation. Copyright © Houghton Mifflin Company

Electromagnetic radiation The energy transmitted from one place to another by light. Types of electromagnetic radiation X-Rays The white light from a light bulb Microwaves used to cook Radio waves that transmit sound Copyright © Houghton Mifflin Company

Figure 11.2: A seagull floating on the ocean moves up and down as waves pass. Notice that the gull just moves up and down with the motion of the waves, it does not move forward. Copyright © Houghton Mifflin Company

3 Components of Waves Wavelengths Frequency speed Copyright © Houghton Mifflin Company

A wavelength (λ) is the distance between two consecutive wave peaks. Copyright © Houghton Mifflin Company

Figure 11.3: The wavelength of a wave. Copyright © Houghton Mifflin Company

Frequency (nu ν ) Frequency indicates how many wave peaks pass a certain point per given time period. i.e how many times does the sea gupp go up and down per minute. Copyright © Houghton Mifflin Company

Speed Speed of the wave indicates how fast a given peak travels through the water. Copyright © Houghton Mifflin Company

Light (electromagnetic radiation) Travels in Waves Different forms of electromagnetic radiation travel at different wavelengths Refer pg 325, fig. 11.4 Sunlight: ultraviolet radiation and visible light Glowing coals transmits heat via infrared radiation. Microwave radiation: water molecules absorb the microwave and this energy is transferred to other molecules by collision (KE). Copyright © Houghton Mifflin Company

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Light = waves that carry energy Photons – tiny energy packets that travel through space in a beam of light. Copyright © Houghton Mifflin Company

Figure 11.5: Electromagnetic radiation. A beam of light can be pictured in two ways: as a wave and as a stream of individual packets of energy called photons Copyright © Houghton Mifflin Company

Figure 11.6: Photons of red and blue light. The photons of red light (long wavelengths) carries less energy than a photon of blue light (shorter wavelengths). Copyright © Houghton Mifflin Company

11.3 Emission of Energy by Atoms Objective: To see how atoms emit light Video – flame test Copyright © Houghton Mifflin Company

The heat from the flame causes atoms to absorb energy. The Colors of Flames Result from Atoms Releasing Energy by Emitting Visible Light The heat from the flame causes atoms to absorb energy. The electrons become excited. Energy is released in the form of light The energy is carried by photons Energy change = energy carried by the photon High energy photons = short-wavelengths Low-energy photons = long-wavelengths Copyright © Houghton Mifflin Company

Figure 11.6: Photons of red and blue light. The photons of red light (long wavelengths) carries less energy than a photon of blue light (shorter wavelengths). Copyright © Houghton Mifflin Company

Figure 11.8: An excited lithium atom emitting a photon of red light to drop to a lower energy state. Copyright © Houghton Mifflin Company

What is the difference between the frequency of a wave and its speed? Focus Questions 11.1 – 11.3 What was wrong with Rutherford’s model of the atom? Why did it need to be modified What is the difference between the frequency of a wave and its speed? What is the relationship between the wavelength of light and the energy of a photon? Copyright © Houghton Mifflin Company

4. How can red light improve germination and production in tomato crops?

11.4 The Energy Levels of Hydrogen Objective: To understand how the emission spectrum of hydrogen demonstrates the quantized nature of energy. Copyright © Houghton Mifflin Company

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Figure 11.9: A sample of H atoms receives energy from an external source. Copyright © Houghton Mifflin Company

Figure 11.9: The excited atoms release energy by emitting photons. Copyright © Houghton Mifflin Company

Figure 11.10: An excited H atom returns to a lower energy level. Copyright © Houghton Mifflin Company

Figure 11.11: Colors and wavelengths of photons in the visible region. Copyright © Houghton Mifflin Company

Figure 11.12: The color of the photon emitted depends on the energy change that produces it. Copyright © Houghton Mifflin Company

Figure 11.13: Each photon emitted corresponds to a particular energy change. Copyright © Houghton Mifflin Company

Figure 11.14: Continuous and discrete energy levels. Copyright © Houghton Mifflin Company

Figure 11.15: The difference between continuous and quantized energy levels. Copyright © Houghton Mifflin Company

11.5 The Bohr Model of the Atom Objective: To learn about Bohr’s model of the hydrogen atom Copyright © Houghton Mifflin Company

Figure 11.17: The Bohr model of the hydrogen atom. Copyright © Houghton Mifflin Company

11.6 The Wave Mechanical Model of the Atom Objective: To understand how electron’s position is represented in the wave mechanical model Copyright © Houghton Mifflin Company

Figure 11.18: A representation of the photo of the firefly experiment. Copyright © Houghton Mifflin Company

Figure 11.19: The orbital that describes the hydrogen electron in its lowest possible energy state. Copyright © Houghton Mifflin Company

Figure 11.20: The hydrogen 1s orbital. Copyright © Houghton Mifflin Company

11.7 The Hydrogen Orbitals Objective: To learn about the shapes of orbitals designated by s, p, and d Copyright © Houghton Mifflin Company

Focus Questions 11.4 – 11.6 Figure 11.11 contains four colored lines. You already know that hydrogen has only one electron. How can we get four lines from one electron? What is wrong with the Bohr model of the atom? How does the wave mechanical model of the atom differ from Bohr’s model? Copyright © Houghton Mifflin Company

Figure 11.21: The first four principle energy levels in the hydrogen atom. Copyright © Houghton Mifflin Company

Figure 11.22: How principal levels can be divided into sublevels. Copyright © Houghton Mifflin Company

Figure 11.23: Principal level 2 shown divided into the 2s and 2p sublevels. Copyright © Houghton Mifflin Company

Figure 11.24: The relative sizes of the 1s and 2s orbital's of hydrogen. Copyright © Houghton Mifflin Company

Figure 11.25: The three 2p orbital's. Copyright © Houghton Mifflin Company

Figure 11.26: Diagram of principal energy levels 1 and 2. Copyright © Houghton Mifflin Company

Figure 11.27: Relative sizes of the spherical 1s, 2s, and 3s orbital's of hydrogen. Copyright © Houghton Mifflin Company

Figure 11.28: The shapes and labels of the five 3d orbital's. Copyright © Houghton Mifflin Company

11.8 The Wave Mechanical Model: Further Development Objectives: To review the energy levels and orbitals of the wave mechanical model of the atom To learn about electron spin Copyright © Houghton Mifflin Company

Focus Question 11.7 – 11.8 What is the difference between an orbit and an orbital in atomic theory? Draw Figure 11.11 and fill in the different types of sublevels for each principal energy level. Tell how many orbitals are found in each type of sublevels: s, p, d, f. What is the Pauli exclusion principal and how does it help us determine where an electron is found within the atom? Copyright © Houghton Mifflin Company

11.9 Electron Arrangement in the First Eighteen Atoms on the Periodic Table Objectives: To understand how the principal energy levels fill with electrons in atoms beyond hydrogen To learn about valence electrons and core electrons Copyright © Houghton Mifflin Company

11.10 Electron Configuration and the Periodic Table Objective: To learn about the electron configuration of atoms with Z greater than 18 Copyright © Houghton Mifflin Company

Figure 11.30: Partial electron configurations for the elements potassium through krypton. Copyright © Houghton Mifflin Company

Figure 11.31: Orbital's being filled for elements in various parts of the periodic table. Copyright © Houghton Mifflin Company

Figure 11.34: Periodic table with atomic symbols, atomic numbers, and partial electron configurations. Copyright © Houghton Mifflin Company

11.11 Atomic Properties and the Periodic Table Objective: To understand the general trends in atomic properties in the periodic table. Copyright © Houghton Mifflin Company

Figure 11.35: Classification of elements as metals, nonmetals, and matalloids. Copyright © Houghton Mifflin Company

Figure 11.36: Relative atomic sizes for selected atoms. Copyright © Houghton Mifflin Company

Write the orbital diagram for the elements listed below. Focus Questions Write the orbital diagram for the elements listed below. Copyright © Houghton Mifflin Company

2. what is the difference between a valence electron and the core electron? Select an element from row 3 and label both using its electron configuration. 3. Elements in vertical columns (families) show similar chemical behavior. How are their electron configurations similar? Copyright © Houghton Mifflin Company

4. Using their positions on the periodic table, write the valence-electron configuration for the following elements. 5. What chemical properties distinguishes a metal from non-metal. 6. How can the property in question 5 be explained using ionization energy trends? Copyright © Houghton Mifflin Company