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Name ____________________________________________________________ Date __________________ Electrons in Atoms Before You Read Chapter 4 Review the structure of the atom by completing the following table. Part of the Atom Description proton a subatomic particle with a positive charge found in the nucleus nucleus centrally located part of the atom that contains protons and neutrons electron negatively charged subatomic part of the atom neutron subatomic particle with no charge found in the nucleus __________ Draw a typical atom and label the structures. Identify three facts about electrons. Example: Electrons are a part of the structure of an atom. Accept all reasonable responses. Possible answers include: 1. ______________________________________________________ Most of an atom consists of electrons. The mass of an electron is extremely small. 2. ______________________________________________________ The negative charge of an electron balances the positive 3. ______________________________________________________ charge of the nucleus. ______________________________________________________ Chemistry: Matter and Change 57 Science Notebook Name ____________________________________________________________ Date __________________ Electrons in Atoms Section 1 Light and Quantized Energy Scan Section 1 of your text. Use the checklist below as a guide. Read all section titles. Read all boldfaced words. Read all tables and graphs. Look at all pictures and read the captions. Write three facts you discovered about light. Accept all reasonable responses. 1. _____________________________________________________ 2. _____________________________________________________ 3. _____________________________________________________ Use your text to define each term. electromagnetic radiation a________________________________________________________ form of energy that exhibits wavelike behavior as it travels through space wavelength the shortest distance between equivalent points on a continuous wave ________________________________________________________ frequency the number of waves that pass through a given point per second ________________________________________________________ amplitude the height of a wave from the origin to a crest or trough ________________________________________________________ electromagnetic spectrum all forms of electromagnetic radiation ________________________________________________________ quantum the minimum amount of energy that can be gained or lost by an atom ________________________________________________________ Planck’s constant value used to determine the energy of a quantum ________________________________________________________ photoelectric effect phenomenon where electrons are emitted from a metal’s surface ________________________________________________________ when light of a certain frequency shines on the surface _______________________________________________________ photon a________________________________________________________ particle of electromagnetic radiation with no mass that carries a quantum of energy atomic emission spectrum set of frequencies of electromagnetic waves emitted by atoms of an element ________________________________________________________ Chemistry: Matter and Change 58 Science Notebook Name ____________________________________________________________ Date __________________ Section 1 Light and Quantized Energy (continued) The Atom and Unanswered Questions List the three reasons scientists found Rutherford’s nuclear atomic model to be fundamentally incomplete. The model did not explain how the atom’s electrons are 1. ______________________________________________________ Use with pages 136. arranged in the space around the nucleus. ______________________________________________________ It did not address the question of why the negatively charged 2. ______________________________________________________ electrons are not pulled into the atom’s positively charged nucleus. ______________________________________________________ It did not account for the differences in chemical behavior 3. ______________________________________________________ among the various elements. ______________________________________________________ Wave Nature of Light Explain the relationship shown by the figure below. Use the following terms: wavelength, frequency, amplitude, and speed. Use with pages 137–140. There is an inverse relationship between wavelength and ______________________________________________________________ frequency. frequency. As wavelength increases, frequency decreases. Speed ________________________________________________________ and amplitude are not affected by wavelength and frequency. ________________________________________________________ ________________________________________________________ Chemistry: Matter and Change 59 Science Notebook Name ____________________________________________________________ Date __________________ Section 1 Light and Quantized Energy (continued) Calculating Wavelength of an EM Wave Use with Example Problem 1, page 140. Solve Read Example Problem 1 in your text. You Try It Problem Radio waves are used to transmit information on various channels. What is the wavelength of a radio wave having the frequency of 5.401010 Hz? 1. Analyze the Problem v = 5.40 1010 Hz and c = 3.00 108 m/s Known: __________________________________________ = ?m UnKnown: __________________________________________ You know that because radio waves are part of the electromagnetic spectrum, their speed, frequency, and wavelength are related by the formula c v. 2. Solve for the Problem Solve the equation relating the speed, frequency, and wavelength of an electromagnetic wave for wavelength (). c/v If c v, then ________ Substitute c and the frequency of the radio wave, v, into the equation. Note that hertz is equivalent to 1/s or s1. 3.00 108 m/s 5.40 1010 s1 Divide the values to determine wavelength, and cancel units as required. 3.00 108 m/s 5.40 10 10 s 1 0.555 102 m 3. Evaluate the Answer wavelength (m) The answer is correctly expressed in a unit of _______________. 3 Both of the known values in the problem are expressed with _______ 3 significant figures, so the answer must have ___________ significant figures. Chemistry: Matter and Change 60 Science Notebook Name ____________________________________________________________ Date __________________ Section 1 Light and Quantized Energy (continued) Particle Nature of Light Identify two facts the wave model of light failed to explain. Heated objects emit only certain frequencies of light at a 1. ______________________________________________________ Use with pages 141–143. given temperature. ______________________________________________________ Some metals emit electrons when colored light of a specific 2. ______________________________________________________ frequency shines on them. ______________________________________________________ Describe Planck’s quantum concept by completing the following statement. energy only The quantum concept concludes that matter can gain or lose _________ quanta in small, specific amounts called ____________. A quantum is the gained or _________ lost minimum amount of energy that can be __________ by an atom. Atomic Emission Spectra Use with pages 144–145. Compare and contrast Einstein’s equation with Planck’s equation by completing the following sentence. Equantum h Planck’s equation, _____________, demonstrates mathematically that the frequency of the emitted radiation. energy of a quantum is related to the ___________ Einstein went further by explaining that, in addition to its wavelike characteristics, a beam of light can be thought of as a stream of tiny particles called __________. photons ____________ Contrast the continuous electromagnetic spectra and the atomic emission spectra. The electromagnetic spectrum is a continuous spectrum of ________________________________________________________ colors because there is no portion of it that does not correspond ________________________________________________________ to a unique wavelength and frequency of light. The atomic ________________________________________________________ emission spectrum, also known as a line spectrum, consists of ________________________________________________________ distinct colored lines of different frequencies. ________________________________________________________ Chemistry: Matter and Change 61 Science Notebook