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SHS, , General Chemistry 2, Quarter 3: Week 2 - Module 2B, Intermolecular Forces of Liquids and, Solids; Solids and their Properties

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STEM – General Chemistry 2, Grade 11 Quarter 3: Week 2 - Module 2B: Intermolecular Forces of Liquids, and Solids; Solids and their Properties, First Edition, 2021, , Copyright © 2021, La Union Schools Division, Region I, , All rights reserved. No part of this module may be reproduced in any form, without written permission from the copyright owners., , Development Team of the Module, , Author: Cristita C. Ferrer, PhD, MT II, Editor: SDO La Union, Learning Resource Quality Assurance Team, Illustrator: Ernesto F. Ramos Jr., P II, Management Team:, Atty. Donato D. Balderas, Jr., Schools Division Superintendent, Vivian Luz S. Pagatpatan, PhD, Assistant Schools Division Superintendent, German E. Flora, Ph.D, CID Chief, Virgilio C. Boado, Ph.D, EPS in Charge of LRMS, Rominel S. Sobremonte, EdD, EPS in Charge of Science, Michael Jason D. Morales, PDO II, Claire P. Toluyen, Librarian II

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General, Chemistry 2, Quarter 3 – Week 2 - Module 2B, Intermolecular Forces of Liquids, and Solids; Solids and their, Properties

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Target, , Solids have fixed volume and fixed shape (regardless of size and shape of, container), high density, cannot be appreciably compressed, and their molecules, vibrate in place., This module will provide you with information and activities that will help you, understand the concept about crystals specifically on the different structures and, properties of crystalline and amorphous solids., After going through this module, you are expected to:, describe the difference in structure of crystalline and amorphous solids, (STEM_GC11IMFIIIa-c-104)., , Jumpstart, , Before going on, let’s check how alert and focus you are as you, do the first activity., Have fun and good luck! Are you ready? Let’s start!, Activity 1: “Decode Me!”, Direction: Decode the clues using the alphabet (e.g.: 1 – A; 2 – B; 5 – E; 10, – J; 19 – S; and the like). Write your answers on a separate paper., 1., Clues: 9 - 15 - 14, (It is an atom or group of atoms that has a net positive or, negative charge.), 2., Clues: 19 - 15 - 12 - 9 - 4, (It is a phase of matter which is described to have very compact, molecules.)

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3., Clues: 3 - 18 - 25 - 19 - 20 - 1 - 12, (It is a form of matter in which the atoms, molecules, or ions are, arranged in a highly ordered three-dimensional lattice.), 4., Clues: 1 - 13 - 15 - 18 - 16 - 8 - 15 - 21 - 19, 19 - 15 - 12 - 9 - 4, (It is any non-crystalline solid in which the atoms and molecules are, not organized in a definite lattice pattern.), 5., Clues: 3 - 18 - 25 - 19 - 20 - 1 - 12, 12 - 1 - 2 - 20 - 9 - 3 - 5, (It is the regular repeating structure of a crystalline solid.), , That’s indeed a good start! Congratulations!, , Discover, , Solids can be categorized into two groups: the crystalline solids and the, amorphous solids. The differences in properties of these two groups of solids arise, from the presence or absence of long-range order of arrangements of the particles, in the solid and their behavior when heated., Classes of Solids, I. Amorphous Solid, The word amorphous means that the solid that does not always adopt, the same form. Amorphous solids have a random orientation of particles,, meaning its constituent particles are randomly arranged., Examples:, Glass, plastic, coal (asphalt), and rubber are considered supercooled liquids where molecules are arranged in a random manner similar to, the liquid state. These solids are the results of the melting, cooling, and, solidifying of liquids before the particles can achieve internal order, (like glass), or having large molecules that are tangled together (like rubber and plastic).

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Amorphous solids do not have sharp melting points which means that, melting within a narrow temperature range. Instead, they soften first and melt, little by little over a wide temperature range., Amorphous solids (e.g. glass), like liquids, do not have long range order,, but may have a limited, localized order in their structures., FYI:, The word “amorphous” from the Greek “ámorphos”, meaning, “shapeless”)., Amorphous solids soften gradually when they are heated. They tend to, melt over a wide range of temperature. This behavior is a result of the, variation in the arrangement of particles in their structures, causing some, parts of the solid to melt ahead of other parts. Amorphous solids soften, gradually when they are heated. They tend to melt over a wide range of, temperature. This behavior is a result of the variation in the arrangement of, particles in their structures, causing some parts of the solid to melt ahead of, other parts., II. Crystalline Solid, It is a solid in which the constituent particles (atoms, ions, or, molecules) have an orderly arrangement, that is, it has regularly arranged, structure units with characteristic geometric forms. Thus, crystals show, regular shapes which reflect the arrangement of the particles with them., Crystalline solids are arranged in fixed geometric patterns or lattices., Examples of crystalline solids are ice and sodium chloride (NaCl), copper, sulfate (CuSO4), diamond, graphite, and sugar (C12H22O11). The ordered, arrangement of their units maximizes the space they occupy and are, essentially incompressible., FYI:, More than 90% of naturally occurring and artificially prepared solids are, crystalline. Minerals, sand, clay, limestone, metals, alloys, carbon (diamond and, graphite), salts (e.g.: NaCl and MgSO4), all have crystalline structures. They have, structures formed by repeating three dimensional patterns of atoms, ions, or, molecules. The repetition of structural units of the substance over long atomic, distances is referred to as long-range order., The structures of crystalline solids are built from repeating units called, crystal lattices. The surroundings of particles in the structure are uniform, and the, attractive forces experienced by the particles are of similar types and strength. These, attractive forces are broken by the same amount of energy, and thus, crystals become, liquids at a specific temperature (i.e., the melting point). At this temperature,, physical properties of the crystalline solids change sharply., Figure 1. Crystalline (left) and amorphous, quartz (right), Image Sources:, 1. http://f.tqn.com/y/chemistry/1/S/a, /d/quartz.jpg, 2. https://upload.wikimedia.org/wikipe, dia/commons/7/71/SilicaGel.jpg

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(a) Pyrite (fool’s gold), , (b) Fluorite, , (c) Amethyst, , Figure, 2., Examples, of, crystalline, solids, (Image, http://www.brainfuse.com/quizUpload/c_83128/crystalline1.GIF), , Charcoal, , Rubber bands, , Glass paper weights, , Source:, , Plastic lunch boxes, , Figure 3. Examples of non-crystalline solids (Image Sources:, http://1.imimg.com/data/P/9/MY-979264/activated, charcoal_10714160_250x250.jpg;, https://upload.wikimedia.org/wikipedia/commons/9/96/Glass_paperweight.jpg, http://healthychild.org/assets/esphoto_plastics_tupperware1-504x334.jpg), Types of Crystalline Solids, In terms of their structure units, crystalline solids may be divided into four, types:, 1. Metallic Crystals, These are the simplest type of structure since single metallic atoms are, the constituent units and can be thought of as three-dimensional arrays, of metal cations embedded into the matrix of negative charges. The merged, valence electrons act as a mobile electron cloud surrounding them., Bonding attractions extend uniformly in all directions. Generally speaking,, a metallic crystal is easily deformed. This explains why metals are, malleable and ductile., Metallic crystals are made of atoms that readily lose electrons to form, positive ions (cations), but no atoms in the crystal would readily gain, electrons. The metal atoms give up their electrons to the whole crystal,, creating a structure made up of an orderly arrangement of cations, surrounded by delocalized electrons that move around the crystal. The, crystal is held together by electrostatic interactions between the cations, and delocalized electron. These interactions are called metallic bonds. This, model of metallic bonding is called the “sea of electrons” model.

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Study the Table on the different observed properties about metallic, crystals given below., Observed Property, Dense, High melting point, , Inference about the Structure, Atoms are packed close together, Strong attractive forces hold the atoms in, the crystal, Good electrical conductor Charged particles move through the crystal, Good heat conductor, Particles can move through the crystal, Malleable and ductile, When the crystal is deformed or stress is, applied, the attractive forces are not broken, Lustrous, Light is easily absorbed and emitted back, Table 1. Observed properties of metallic crystals, Look carefully at the figure below. What do you observe?, , Figure 4. Positive ions surrounded by delocalized electrons (Image source:, http://wps.prenhall.com/wps/media/objects/3311/3391416/imag1108/AAAUBA, F0.JPG), This model is able to explain many physical properties of metals, such as, their high melting points, malleability, ductility, thermal and electrical conductivity,, and luster., a. High melting point – a large amount of energy is needed to melt the crystal, since the forces of attraction to be broken are numerous and extend, throughout the crystal, b. Dense – atoms are packed closely together. Metals exhibit close-packing, structures, a most economical way by which atoms utilize space, c. Electrical conductivity – then delocalized electrons move throughout the, crystal, d. Thermal or heat conductor – the delocalized electrons collide with each, other as they move through the crystal, and it is through these collisions, that kinetic energy is transferred, e. Malleability/ductility – when stress is applied to the metal, the metal, cations shift in position, but the mobile electrons simply follow the, movement of the cations. The attractive forces between cations and mobile, electrons are not broken

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f. Luster – the motion and collisions of electrons allow it to gain and lose, energy, some of these in the form of emitted light that is observed as luster, 2. Ionic Crystals, These crystals have ions as constituent particles meaning they are, made of ions (cations and anions). These ions form strong electrostatic, interactions that hold the crystal lattice together. The electrostatic attractions, are numerous and extend throughout the crystal since each ion is surrounded, by several ions of opposite charge, making ionic crystals hard and of high, melting points. A good example of this is sodium chloride crystal. The, oppositely charged Na+ and Cl- ions arranged in a regular three-dimensional, pattern of crystal lattice., Study the Table on the different observed properties about ionic, crystals given below., Observed Property, Hard, , Inference about the Structure, Strong attractive forces hold the crystal, together, High melting point, Strong attractive forces have to be broken to, melt the crystal, Poor electrical conductor No charged particles move through the, in the solid state, crystal, Good electrical conductor in Mobile charged particles are present in the, the molten state, molten state, Brittle, Deformation or shift of particles cause, attractive forces to be broken, Table 2. Observed properties of ionic crystals, Ionic substances can conduct electricity in the liquid or molten state or, when dissolved in water, indicating that in these states, charged particles are, able to move and carry electricity. However, the solid state is generally, nonconducting since the ions are in fixed positions in the crystal lattice and, are unable to move from one point to another., Ionic crystals are brittle, and would shatter into small pieces when, deformed or when pressure is applied on the crystal. The shifting of ions, causes repulsions between particles of like charges., , Figure 5. Shifting of ions cause repulsions in ionic crystal (Image, Source:https://encryptedtbn1.gstatic.com/images?q=tbn:ANd9GcRLoXX, kQsqpNSBX3vTHxDaQxfuKU-borNlufdFB2Vaoo882KCRe)

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3. Molecular Crystals, These crystals are those which have molecules as constituent particles, as well as structure units. The molecules present in this crystal are held, by weak van der Waals forces of attraction. The solid iodine (I2) molecules, in a crystalline form is a good example of this type., Molecular crystals are made of atoms, such as in noble gases, or, molecules, such as in sugar (C12H22O11), iodine (I2), and naphthalene, (C10H8). The atoms or molecules are held together by a mix of hydrogen, bonding/dipole-dipole and dispersion forces, and these are the attractive, forces that are broken when the crystal melts. Hence, most molecular, crystals have relatively low melting points., Study the Table on the different observed properties about ionic, crystals given below., Observed Property, Soft, , Inference about the Structure, Weak attractive forces hold the crystal, together, Low melting point, Weak attractive forces are broken when, crystals melt, Poor electrical conductor No charged particles move through the, in the solid and molten crystal, states, Poor heat conductor, No particles can move easily throughout the, crystal, Brittle, Deformation or shift of particles cause, attractive forces to be broken, Table 3. Observed properties of molecular crystals, The valence electrons of molecular substances are used in bonding, and, cannot move about the crystal structure. Hence, the crystals are, nonconducting. The absence of any mobile particles makes molecular crystals, unable to transmit heat fast. The crystals are brittle because the attractive, forces that hold the molecules in the crystal are highly directional and a shift, in positions of the molecules would break them., 4. Covalent Network Crystals, These are giant molecules of macromolecules which consist of very, large numbers of atoms linked by a network of covalent bonds. Asbestos,, mica, and graphite are good examples of covalent network crystals. Aside, from graphite, diamond is another crystalline form of carbon where its, atoms are linked by covalent bonds in three direction, thus, the entire, crystal becomes a single molecule., FYI:, There are some substances which have molecules or ions that can assume more, than one stable arrangement in the solid state. This property is called as, polymorphism., Allotropes are the different molecular forms or various crystal modifications of, a polymorphous element. The element carbon has allotropic forms – graphite,, diamond and buckminsterfullerene.

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Consider the Table on the different observed properties about covalent, network crystals given below., Observed Property, Hard, , Inference about the Structure, Strong attractive forces hold the crystal, together, Very high melting point, Strong attractive forces have to be broken, in order to melt crystals, Poor electrical conductor No charged particles move through the, in the solid and molten crystal, states, Poor heat conductor, No particles can move easily throughout the, crystal, Brittle, Deformation or shift of particles cause, attractive forces to be broken, Table 4. Observed properties of covalent network crystals, Diamonds are an example of a covalent network solid in which atoms are, covalently bonded with each other. They tend to be hard and have high melting, points. Silicon dioxide, SiO2 is an example of a covalent network solid in which atoms, are covalently bonded to each other. Notice that each silicon atom is bridged to its, neighbors by an oxygen atom., Graphite, an allotrope of carbon, differs in properties from other network, solids. It is soft and is used as a solid lubricant. It is also a good conductor of, electricity, indicating the presence of charged particles that move through the crystal., In graphite, each carbon atom is bonded to only three other carbon atoms, while in, diamond, each carbon atom is bonded to four others. In addition, graphite is made, up of layers of rings of carbon atoms. The broken lines connecting the layers are, weak dispersion forces., Remember Me!, Type of, Solid, Metallic, , Ionic, , Molecular, , Form of, Unit, Particles, Atoms, , Forces, Between, Particles, Metallic, bonds, , Positive and, negative, ions, , Electrostatic, attractions, , Atoms or, molecules, , London, dispersion, forces,, dipole-dipole, forces,, hydrogen, bonds, , Properties, , Examples, , Soft to very hard, low to, very high melting point,, excellent thermal and, electrical, conduction,, malleable and ductile, Hard and brittle, high, melting point, often poor, thermal and electrical, conduction, Fairly soft, moderately, high melting point, poor, thermal and electrical, conduction,, , All metallic, elements like, Cu, Fe, Al, Pt, Typical salts, like, NaCl,, Ca(NO3)2, Argon (Ar),, methane, (CH4),, sucrose, (C12O22O11),, Dry, (CO2), , ice, , TM

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Type of, Solid, Covalent, Network, , Form of, Unit, Particles, Atoms, connected, in a, network, of covalent, bonds, , Forces, Between, Particles, Covalent, bonds, , Properties, Very hard, very high, melting point, often, very poor thermal and, electrical conduction, , Examples, Diamond (C),, Quarts (SiO2), , Table 5. Comparison of the types of crystalline solids, Just Thinking!, What is the distinguishing feature of crystalline solids? How are the structures, of crystals determined?, The Crystal Lattice, Crystalline solids are characterized by a regular repeating structure called the, crystal lattice., It’s View Time!, Watch a video clip on growing crystals using the given link. This will help, visualize how some crystals are formed. https://www.youtube.com/watch?v=sdYS3J85Pw.

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Explore, , To explore and master these concepts, here is an, enrichment activity prepared for you! Keep going! You can do, it! Enjoy!, , Enrichment Activity 1: “Check Me If You Can!”, Direction: Indicate the strongest force holding the crystals together in the, following substances by putting a check on the appropriate box. Write your answer, on a separate paper., Type of Crystal, Substance, , Metallic, , Ionic, Dispersion, Forces, , e.g.: Pb, I2, 1. Kr, , Covalent, Network, , Molecular, DipoleDipole, Forces, , Hydrogen, Bonds, , ∕, ∕, , 2. HF, 3. NO, 4. Al, 5. K2S, 6. HCl, 7. KMnO4, 8. Cgraphite, 9. Ag, 10. CaO, , You are really doing great! That’s amazing!

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Deepen, To deeply and practically apply our lesson in your, real-life situation, do the next task., , Performance Task:, Goal: To write a four to six paragraph essay about a crystal of your choice by, answering the following questions:, 1. How is the crystal formed?, 2. Is it beneficial or harmful to man or both? Discuss how it is beneficial or, harmful to man., 3. If it is something harmful, what can be done to avoid its formation? If it is, something beneficial, how can its formation be promoted?, Note: Write your essay on a short bond paper. Cite your sources, following the APA format. Choose the crystal from the given list, below:, a., b., c., d., e., f., g., , Oxides of magnesium and calcium produced from hard water, Calcium oxalate or calcium phosphate in kidney stones, Uric acid in gout, Barium sulfate in x-ray imaging, Silica in desiccants, Gemstones used for jewelry, Salts in food industry, e.g. table salt, monosodium glutamate,, potassium nitrate, h. Metals or alloys used in conductors, Role: You are an essayist, Audience: Teachers and classmates, Situation: You are invited to share your insights about the formation of crystals, and their benefits and harmful effects. Moreover, share how you will, promote the crystal if it is beneficial or how you will convince your, audience not to use the crystal if it is harmful., Product/Performance: An essay about your selected crystal and a three to five, minute, video, presentation, sharing, your, insights. The, presentation, should, include, appropriate, photographs,, video, music, graphs, and other visual aids. The final project should, be submitted using Google Form, Google Drive, or flashdrive., Standard: Criteria for your task is shown in the given rubric on the next page:

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Rubric for Essay: High School, CRITERIA, , Focus/ Main, Point, , Support, , Organization, & Format, (Paragraphs,, Transitions), Language, Use, Style &, Conventions, (Sentence, structure,, word choice,, grammar,, spelling,, punctuation), , Originality, (Expression, of the theme, in a creative, way), , Highly, Proficient, (4), The essay is, focused,, purposeful, and, reflects, clear, insight, and, ideas., Persuasively, supports main, point with welldeveloped, reasons and/or, examples, Effectively, organizes ideas, to, build, a, logical, coherent, argument, Effective, and, creative use of, elements, of, style to enhance, meaning Uses, correct, grammar,, spelling,, punctuation, throughout with, very few errors, Distinctive, experimentation, with language, and usage to, enhance, concepts, Applies higher, order thinking, and, creative, skills to relay, complex ideas, , Proficient, (3), , Developing, (2), , Beginning, (1), , The essay is, focused on the, topic, and, includes, relevant ideas., , The essay is, focused on topic, and, includes, few, loosely, related ideas., , The, essay, poorly, addresses topic, and, includes, irrelevant ideas., , Supports main, point, with, developed, reasons and/or, examples, , Supports main, point with some, underdeveloped, reasons and/or, examples, , Provides little or, no support for, the main point, , Organizes ideas, to, build, an, argument, , Some, organization of, ideas to build, an argument, , Little, or, no, organization of, ideas to build, an argument, , Appropriate use, of elements of, style, Uses, correct, grammar,, spelling,, and, punctuation, with few errors, , Some use of, elements, of, style Contains, frequent errors, in, grammar,, spelling,, and, punctuation, , Little or no use, of elements of, style, Many, errors, in, grammar,, spelling,, and, punctuation,, makes reader’s, comprehension, difficult, , Sufficient, experimentation, with language, and usage to, enhance, concepts, Applies, basic, creative skills to, relay ideas, , Very, little, experimentation, to, enhance, concepts Does, not, exhibit, creativity, , No, experimentation, nor, enhancement of, concepts, No, adherence, to, the theme, , Adapted from https://www.kpu.ca/sites/default/files/NEVR/High%20School%20Rubrics.pdf, , SCORE

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Rubric for Video Presentation: High School, CRITERIA, , Concept, , Script/, Storyboard, , Content/, Organization, , Highly, Proficient, (4), Has, a, clear, picture of what, he/she is trying, to, achieve., Adequate, description, of, what he/she is, trying to do and, generally, how, his/her work will, contribute to the, final project., The, storyboard, illustrates, the, video, presentation, structure, with, thumbnail, sketches of each, scene. Notes of, proposed, transition, special, effects,, sound, and title tracks, incl: text, color,, placement,, graphics,, etc., Notes, about, proposed, dialogue/, narration text are, included., The, content, includes a clear, statement, of, purpose or theme, and is creative,, compelling, and, clearly written. A, rich variety of, supporting, information in the, video contributes, to, the, understanding of, the project’s main, idea. Events and, messages, are, presented in a, logical, order., Includes properly, cited sources., , Proficient, (3), , Developing, (2), , Beginning, (1), , Has a fairly clear, picture of what, he/she is trying, to achieve., Can, describe, what he/she is, trying, to, do, overall but has, trouble, describing, how, his/her work will, contribute to the, final project., The, storyboard, includes, thumbnail, sketches of each, video scene and, includes text for, each segment of, the presentation,, descriptions, of, background, audio for each, scene, and notes, about proposed, shots, and, dialogue., , Has brainstormed, his/her concept,, but no clear focus, has, emerged., Goals/final, product, not, clearly defined., , Little effort has, been spent on, brainstorming, and refining a, concept. Unclear, on the goals and, how the project, objectives will be, met., , The, thumbnail, sketches on the, storyboard, are, not, in, logical, sequence and do, not, provide, complete, descriptions, of, the video scenes,, audio, background,, or, notes about the, dialogue., , There, is, no, evidence, of, a, storyboard, or, script., , Information, is, presented as a, connected theme, with, accurate,, current, supporting, information that, contributes, to, understanding, the project’s main, idea. Details are, logical, and, persuasive, information, is, effectively used., The, content, includes a clear, point of view with, a progression of, ideas, and, supporting, information., Includes properly, cited sources., , The content does, not present a, clearly, stated, theme, is vague,, and some of the, supporting, information does, not seem to fit the, main, idea, or, appears, as, a, disconnected, series of scenes, with no unifying, main, idea., Includes, few, citations and few, facts., , Content lacks a, central, theme,, clear point of view, and, logical, sequence, of, information., Much, of, the, supporting, information, is, irrelevant to the, overall message., The, viewer is, unsure what the, message, is, because there is, little persuasive, information and, only one or two, facts about the, topic, are, articulated., Information, is, incorrect, out of, date,, or, incomplete., No, citations, included., , SCORE

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CRITERIA, , Highly, Proficient, (4), Video, was, completed, and, had all required, elements., The, video was well, edited and moves, smoothly, from, scene to scene, with proper use of, transitions. Audio, and, other, enhancements, were well used., , Proficient, (3), , Developing, (2), , Video, was Video was made,, completed, and but had very little, contained, all if any editing., required, items. Many poor shots, Editing was not remain., Video, done as well as it was, very, should, have fragmented and, been. Some poor choppy with little, Quality, shots, remain. to, no, audio, Movie, is, still reinforcement., somewhat, choppy., Audio, and, other, enhancements, were utilized, but, not for maximum, effect., Video, was Video, was Video, was, submitted, on submitted 1 or 2 submitted 3 or 4, Timeliness, time., days after the days after the, deadline., deadline., Adapted from lambenglishmontana.wikispaces.com/file/view/RubricVideo.doc, , Beginning, (1), , SCORE, , There was no, video, or was, totally unedited, with, no, transitions, or, audio support of, any kind., , Video, was, submitted 5 or, more days after, the deadline., , Gauge, , You are now on the last part of your module. To, assess how much you have understood the lesson, you are, asked to answer a 15-point Multiple Choices type of test., Keep going! Good luck!, Direction: Write the CAPITAL letter of the correct answer on a separate paper., (15 points), 1. Which of the following types of crystals is described to have orderly-arranged, constituent particles?, A. amorphous, B. crystalline, C. ionic, D. molecular, 2. Which of the following types of crystal is described to have randomly-arranged, constituent particles?, A. amorphous, B. crystalline, C. ionic, D. molecular, 3. Which of the following statements DOES NOT describe crystalline solids?, A. They show regular shapes., B. Its structures are regularly arranged., C. They do not have sharp melting points., D. The ordered arrangement of their units maximizes the space they occupy.

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*For numbers 4 to 7, refer to the given choices below:, A. covalent network, , B. ionic, , C. metallic, , D. molecular, , 4. In which type of crystalline solid does gold, Au, belong?, 5. In which type of crystalline solid does iodine molecule, I2, belong?, 6. In which type of crystalline solid does potassium sulfide, K2S, belong?, 7. In which type of crystalline solid does graphite belong?, 8. Which of the following properties DOES NOT describe metallic crystalline, solids?, A. brittle, B. ductile, C. malleable, D. good conductor of heat, 9. Which of the following properties characterizes covalent network crystalline, solids?, A. brittle, B. high melting point, C. poor conductor of electricity, D. with cations and anions very, 10. Which of the following phrases about molecular crystalline solid is FALSE?, A. fairly soft, B. poor thermal conduction, C. made up of atoms or molecules, D. very high electrical conduction, 11. Which of the following phrases about ionic crystalline solid is TRUE?, A. very hard, B. good thermal conduction, C. high melting point, D. very high electrical conduction, 12. Why is metallic crystalline solid a good conductor of electricity?, A. Atoms are packed close together., B. Particles can move through the crystal., C. The charged particles move through the crystal., D. Strong attractive forces hold the atoms in the crystal., 13. Why is ionic crystalline solid characterized to be hard?, A. No charged particles move through the crystal., B. Strong attractive forces hold the crystal together., C. Mobile charged particles are present in the molten state., D. Strong attractive forces have to be broken to melt the crystal., 14. Why is molecular crystalline solid characterized to have low melting point?, A. No charged particles move through the crystal., B. Weak attractive forces hold the crystal together., C. No particles can move easily throughout the crystal, D. Weak attractive forces are broken when crystals melt., 15. Why is covalent network crystal characterized to be hard?, A. No charged particles move through the crystal., B. Strong attractive forces hold the crystal together., C. No particles can move easily throughout the crystal., D. Strong attractive forces have to be broken in order to melt crystals., , Congratulations!!! You did very well in this module!!!

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Answer Key