Before You Read Review scientific law Define the following terms describes a relationship in nature that is supported by many experiments theory an explanation supported by many experiments; is still subject to new experimental data, can be modified, and is considered successful if it can be used to make predictions that are true element a pure substance that cannot be separated into simpler substances by physical or chemical means law of definite proportions law of multiple proportions states that regardless of the amount, a compound is always composed of the same elements in the same proportion by mass states that when different compounds are formed by a combination of the same elements, different masses of one element combine with the same mass of the other element in a ratio of small whole numbers Describe three things that you already know about the atom 1 Accept all reasonable responses 2 3 43
Section 41 Early Theories of Matter I&E 1d, 1k, 1n 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 Think about what you already know about this subject List three things you expect to learn about while reading the section 1 Accept all reasonable responses 2 3 New Dalton s atomic theory Use your text to define each term a theory proposed by John Dalton in 1808, based on numerous scientific experiments, which marked the beginning of the development of modern atomic theory atom the smallest particle of an element that retains the properties of the element Academic accurate having a measured value close to the accepted value conclude making a judgment based on the information obtained reveal 44 Define the following term to make something known Early Theories of Matter
Section 41 Early Theories of Matter (continued) The Philosophers Use with pages 87 89 Summarize the effect that Aristotle had on the atomic theory proposed by Democritus Aristotle rejected Democritus ideas because it did not agree with his ideas on nature He did not believe that the nothingness of empty space could exist He denied the existence of atoms People accepted Aristotle s conclusions for 2,000 years, and the ideas of Democritus were not developed John Dalton Use with pages 89 90 List the main points of Dalton s atomic theory 1 All matter is composed of extremely small particles called atoms 2 All atoms of a given element are identical in size, mass, and chemical properties Atoms of one element are different from those atoms of any other element 3 Atoms cannot be created, divided into smaller particles, or destroyed 4 Different atoms combine in simple whole-number ratios to form compounds 5 In a chemical reaction, atoms are separated, combined, or rearranged Discuss Dalton s ideas by completing the following paragraph After years of studying chemical reactions, Dalton was able to accurately determine the mass ratios of the elements involved in the reactions His conclusions resulted in the atomic theory, atoms in chemical reactions rearrange, but are not created, which helped to explain that separate, combine, or destroyed, or divided 45
Section 41 Early Theories of Matter (continued) Compare and contrast the atomic theories of Democritus and Dalton Mark an under each name if a statement in the table applies to that person s theory Statement All matter is made of tiny pieces Democritus Dalton Matter is made of empty space through which atoms move Atoms cannot be divided Atoms cannot be created Atoms cannot be destroyed Different atoms combine in whole-number ratios to form compounds Defining the Atom Use with pages 90 91 The properties of atoms vary based on shape, size, and movement Different kinds of atoms come in different sizes and shapes Explain an atom by completing the following statements The atom is the smallest particle that retains the properties of the element When a group of atoms unit bond together, the result is known as a molecule and act as a R EAL-W ORLD CONNECTION The experiments of the alchemists revealed the properties of some metals and provided the foundation for the science of chemistry Although not successful, alchemy proved beneficial to science Explain how this example can be applied to modern research Accept all reasonable responses Possible answer: Even research and experiments that do not succeed add to our body of knowledge and provide useful information to later researchers 46 Early Theories of Matter
Section 42 Subatomic Particles and the Nuclear Atom Chemistry 1e, 1h, 11g; I&E 1n Scan Section 2 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 Think about what you already know about this subject Write three facts you discovered about subatomic particles 1 Accept all reasonable responses 2 3 New cathode ray Use your text to define each term ray of radiation emitting from the cathode end of a tube used by researchers to study mass and charge electron negatively charged particles that are part of all forms of matter tiny, dense, centrally located region within the atom that contains all of an atom s positive charge and virtually all of its mass proton a subatomic particle carrying a charge equal to but opposite that of an electron; that is, a positive charge of 1+ neutron a subatomic particle with a mass nearly equal to that of a proton, but that has no electrical charge Academic concentrate Define the following term to build up or combine substances at one location or into one mass 47
Section 42 Subatomic Particles and the Nuclear Atom Discovering the Electron (continued) Summarize the information you learned from cathode ray experiments Use Figure 4-8 for reference Use with pages 92 94 Cathode Ray Experiment Cathode ray is deflected toward the positively charged plate by an electric field Altering the gas in the tube and the material used for the cathode have no effect Proves: Cathode ray is deflected in a magnetic field Proves: Particles in the ray Cathode rays have a are part of all matter negative charge Indicates: Cathode ray is composed of charged particles Identify the major discoveries about subatomic particles made by the 19 th century 1 Cathode rays were actually a stream of charged particles 2 The particles carried a negative charge 3 There were particles smaller than atoms 48 Subatomic Particles and the Nuclear Atom
Section 42 Subatomic Particles and the Nuclear Atom The Nuclear Atom Use with pages 94 95 Describe Rutherford s model of the atom by completing the following statements 1 Most of an atom consists of empty space through held 2 The electrons are 3 The volume of Use with pages 96 97 moving rapidly within the atom by their attraction space larger is many times electrons to the positively charged Completing the Atom The Discovery of Protons and Neutrons (continued) through which the electrons move than the volume of the Organize the properties of subatomic particles by completing the table below Use Table 4-1 for reference Electron Proton Neutron e p n0 Location surrounding the in in Relative electrical charge 1 1 0 Symbol Summarize what you have learned about subatomic particles by completing the following paragraph Atoms have a spherical is made up of protons neutrons that have no 9997% charge The makes up atom of the mass of an atom Most of an positively electrons charged The attraction of an atom that have a positive charge and made up of negatively charged by their shape The is traveling around the electrons are held in place to the positive charge of the The mass of the protons and neutrons are almost each other while the mass of the electrons is equal to extremely small 49