考研英语阅读分析详解例20
<p> <span word="One">One</span> <span word="of">of</span> <span word="the">the</span> <span word="simplest">simplest</span> <span word="and">and</span> <span word="best">best</span> <span word="known">known</span> <span word="kinds">kinds</span> <span word="of">of</span> <span word="crystal">crystal</span> <span word="is">is</span> <span word="the">the</span> <span word="ionic">ionic</span> <span word="salt">salt</span>, <span word="of">of</span> <span word="which">which</span> <span word="a">a</span> <span word="typical">typical</span> <span word="example">example</span> <span word="is">is</span> <span word="sodium">sodium</span> <span word="chloride">chloride</span>, <span word="or">or</span> <span word="ordinary">ordinary</span> <span word="table">table</span> <span word="salt">salt</span>. <span word="The">The</span> <span word="fundamental">fundamental</span> <span word="components">components</span> <span word="of">of</span> <span word="an">an</span> <span word="ionic">ionic</span> <span word="salt">salt</span> <span word="are">are</span> <span word="ions">ions</span>: <span word="atoms">atoms</span> <span word="or">or</span> <span word="molecules">molecules</span> <span word="that">that</span> <span word="have">have</span> <span word="become">become</span> <span word="electrically">electrically</span> <span word="charged">charged</span> <span word="by">by</span> <span word="gaining">gaining</span> <span word="or">or</span> <span word="losing">losing</span> <span word="one">one</span> <span word="more">more</span> <span word="electrons">electrons</span>. <span word="In">In</span> <span word="forming">forming</span> <span word="sodium">sodium</span> <span word="chloride">chloride</span>, <span word="for">for</span> <span word="example">example</span>, <span word="sodium">sodium</span> <span word="atoms">atoms</span> <span word="give">give</span> <span word="up">up</span> <span word="an">an</span> <span word="electron">electron</span> <span word="and">and</span> <span word="chlorine">chlorine</span> <span word="atoms">atoms</span> <span word="gain">gain</span> <span word="an">an</span> <span word="electron">electron</span> . <span word="The">The</span> <span word="ions">ions</span> <span word="are">are</span> <span word="attracted">attracted</span> <span word="to">to</span> <span word="one">one</span> <span word="another">another</span> <span word="by">by</span> <span word="their">their</span> <span word="opposite">opposite</span> <span word="charges">charges</span>, <span word="and">and</span> <span word="they">they</span> <span word="stack">stack</span> <span word="together">together</span> <span word="compactly">compactly</span>, <span word="like">like</span> <span word="tightly">tightly</span> <span word="packed">packed</span> <span word="spheres">spheres</span>.</p><p> <span word="Recently">Recently</span>, <span word="scientists">scientists</span> <span word="at">at</span> <span word="Michigan">Michigan</span> <span word="State">State</span> <span word="University">University</span> <span word="created">created</span> <span word="a">a</span> <span word="new">new</span> <span word="kind">kind</span> <span word="of">of</span> <span word="crystal">crystal</span> <span word="called">called</span> <span word="an">an</span> <span word="electride">electride</span>. <span word="In">In</span> <span word="electrides">electrides</span>, <span word="the">the</span> <span word="anions">anions</span> <span word="are">are</span> <span word="completely">completely</span> <span word="replaced">replaced</span> <span word="by">by</span> <span word="electrons">electrons</span>, <span word="which">which</span> <span word="are">are</span> <span word="trapped">trapped</span> <span word="in">in</span> <span word="naturally">naturally</span> <span word="formed">formed</span> <span word="cavities">cavities</span> <span word="within">within</span> <span word="a">a</span> <span word="framework">framework</span> <span word="of">of</span> <span word="regularly">regularly</span> <span word="stacked">stacked</span> <span word="cations">cations</span> . <span word="Electrides">Electrides</span> <span word="are">are</span> <span word="the">the</span> <span word="first">first</span> <span word="examples">examples</span> <span word="of">of</span> <span word="ionic">ionic</span> <span word="salts">salts</span> <span word="in">in</span> <span word="which">which</span> <span word="all">all</span> <span word="these">these</span> <span word="anionic">anionic</span> <span word="sites">sites</span> <span word="are">are</span> <span word="occupied">occupied</span> <span word="solely">solely</span> <span word="by">by</span> <span word="electrons">electrons</span>.</p><p> <span word="Unlike">Unlike</span> <span word="other">other</span> <span word="types">types</span> <span word="of">of</span> <span word="anions">anions</span>, <span word="anionic">anionic</span> <span word="electrons">electrons</span> <span word="do">do</span> <span word="not">not</span> <span word="behave">behave</span> <span word="as">as</span> <span word="if">if</span> <span word="they">they</span> <span word="were">were</span> <span word="simple">simple</span> <span word="charged">charged</span> <span word="spheres">spheres</span>. <span word="In">In</span> <span word="particular">particular</span>, <span word="because">because</span> <span word="of">of</span> <span word="their">their</span> <span word="low">low</span> <span word="mass">mass</span> <span word="and">and</span> <span word="their">their</span> <span word="tendency">tendency</span> <span word="to">to</span> <span word="interact">interact</span> <span word="with">with</span> <span word="one">one</span> <span word="another">another</span> <span word="over">over</span> <span word="great">great</span> <span word="distances">distances</span>, <span word="they">they</span> <span word="cannot">cannot</span> <span word="be">be</span> <span word="pinned">pinned</span> <span word="down">down</span> <span word="to">to</span> <span word="any">any</span> <span word="one">one</span> <span word="location">location</span>. <span word="Instead">Instead</span>, <span word="they">they</span> <span word="wander">wander</span> <span word="close">close</span> <span word="to">to</span> <span word="and">and</span> <span word="among">among</span> <span word="the">the</span> <span word="atoms">atoms</span> <span word="lining">lining</span> <span word="the">the</span> <span word="cavity">cavity</span> <span word="and">and</span> <span word="interact">interact</span> <span word="with">with</span> <span word="electrons">electrons</span> <span word="in">in</span> <span word="nearby">nearby</span> <span word="cavities">cavities</span>, <span word="perhaps">perhaps</span> <span word="changing">changing</span> <span word="places">places</span> <span word="with">with</span> <span word="them">them</span>.</p><p> <span word="The">The</span> <span word="properties">properties</span> <span word="of">of</span> <span word="an">an</span> <span word="electride">electride</span> <span word="depend">depend</span> <span word="largely">largely</span> <span word="on">on</span> <span word="the">the</span> <span word="distance">distance</span> <span word="between">between</span> <span word="the">the</span> <span word="cavities">cavities</span> <span word="that">that</span> <span word="hold">hold</span> <span word="trapped">trapped</span> <span word="electrons">electrons</span>. <span word="When">When</span> <span word="the">the</span> <span word="trapped">trapped</span> <span word="electrons">electrons</span> <span word="are">are</span> <span word="far">far</span> <span word="apart">apart</span>, <span word="they">they</span> <span word="do">do</span> <span word="not">not</span> <span word="interact">interact</span> <span word="strongly">strongly</span>, <span word="and">and</span> <span word="so">so</span> <span word="behave">behave</span> <span word="somewhat">somewhat</span> <span word="like">like</span> <span word="an">an</span> <span word="array">array</span> <span word="of">of</span> <span word="isolated">isolated</span> <span word="negative">negative</span> <span word="charges">charges</span>. <span word="When">When</span> <span word="they">they</span> <span word="are">are</span> <span word="closer">closer</span> <span word="together">together</span>, <span word="they">they</span> <span word="begin">begin</span> <span word="to">to</span> <span word="display">display</span> <span word="properties">properties</span> <span word="associated">associated</span> <span word="with">with</span> <span word="large">large</span> <span word="ensembles">ensembles</span> <span word="of">of</span> <span word="identical">identical</span> <span word="particles">particles</span>. <span word="When">When</span> <span word="they">they</span> <span word="are">are</span> <span word="still">still</span> <span word="closer">closer</span>, <span word="the">the</span> <span word="ensemble">ensemble</span> <span word="properties">properties</span> <span word="dominate">dominate</span> <span word="and">and</span> <span word="the">the</span> <span word="electrons">electrons</span> <span word="delocalize">delocalize</span>: <span word="they">they</span> <span word="are">are</span> <span word="no">no</span> <span word="longer">longer</span> <span word="tightly">tightly</span> <span word="bound">bound</span> <span word="within">within</span> <span word="individual">individual</span> <span word="cavities">cavities</span> <span word="but">but</span> <span word="are">are</span> <span word="more">more</span> <span word="or">or</span> <span word="less">less</span> <span word="free">free</span> <span word="to">to</span> <span word="pass">pass</span> <span word="through">through</span> <span word="the">the</span> <span word="spaces">spaces</span> <span word="within">within</span> <span word="the">the</span> <span word="framework">framework</span> <span word="of">of</span> <span word="positive">positive</span> <span word="ions">ions</span>.</p>
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