Ice | Definition, Structure, Properties, Freezing Point, & Facts

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btn-circle shadow btn-blue " aria-label="Next"> <span class="material-icons md-24" data-icon="keyboard_arrow_right"></span> </button> </div> </div> </div> <main> <div class="md-page-wrapper"> <div id="content" class="md-content"> <div class="md-article-container template-desktop infinite-pagination"> <div class="infinite-scroll-container article last"> <article class="article-content container-lg qa-content px-0 pt-0 pb-40 py-lg-20 content md-expanded" data-topic-id="281026"> <div class="grid gx-0"> <div class="col-auto"> <div class="topic-left-rail md-article-drawer position-relative d-flex border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/science/ice">ice</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/science/ice">Introduction</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref65756"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/ice#ref65756">Structure</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref65757"><a class="w-100 link-gray-900" href="/science/ice#ref65757">The water molecule</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref65758"><a class="w-100 link-gray-900" href="/science/ice/The-ice-crystal">The ice crystal</a></li></ul></div></li><li data-target="#ref65759"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/ice/The-ice-crystal#ref65759">Properties</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref65760"><a class="w-100 link-gray-900" href="/science/ice/The-ice-crystal#ref65760">Mechanical properties</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref65761"><a class="w-100 link-gray-900" href="/science/ice/The-ice-crystal#ref65761">Thermal properties</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref65762"><a class="w-100 link-gray-900" href="/science/ice/The-ice-crystal#ref65762">Optical properties</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref65763"><a class="w-100 link-gray-900" href="/science/ice/The-ice-crystal#ref65763">Electromagnetic properties</a></li></ul></div></li></ul> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/science/ice/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/ice">Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/science/ice/images-videos">Images & Videos</a> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 "> <div class="slider-container js-slider-container overflow-hidden d-flex overflow-hidden text-nowrap ml-15"> <a href="https://cdn.britannica.com/09/125909-050-1AFFD851/iceberg-waters-Greenland.jpg" data-href="/media/1/281026/120202" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/09/125909-004-82A92500/iceberg-waters-Greenland.jpg" alt="iceberg" height="50" /> </a> <a href="https://cdn.britannica.com/91/151891-050-D4C0CD6F/Ice-cubes.jpg" data-href="/media/1/281026/160984" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/91/151891-004-DEAF2BE7/Ice-cubes.jpg" alt="ice cubes" height="50" /> </a> <a href="https://cdn.britannica.com/79/149179-050-DC23D823/snowflake-threads-wool-coat.jpg" 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Meier</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Professor of Geological Sciences, University of Colorado, Boulder; former Director, Institute of Arctic and Alpine Research.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Mark F. Meier</span>, <div class="editor-popover popover p-0"> <a class="d-block p-20 qa-editor-popup gtm-byline font-12 byline-contributor" href="/contributor/George-D-Ashton/4103" > <div class="editor-title font-16 font-weight-bold">George D. Ashton</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Chief, Research Division, U.S. Army Cold Regions Research and Engineering Laboratory, U.S. Army Corps of Engineers, Hanover, New Hampshire. Author of <i>River Ice</i> and others.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> George D. 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They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <a class="byline-edit-history" href="https://www.britannica.com/science/ice/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 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href="/science/iceberg" topicid="281212">iceberg</a></dd> <dd><a href="/science/c-axis" topicid="87357">c-axis</a></dd> <dd><a href="/science/columnar-ice" topicid="127175">columnar ice</a></dd> <dd><a href="/science/ice-crystal" topicid="839845">ice crystal</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/ice"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><div class="assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100" data-type="other"><div class="slider-container js-slider-container overflow-hidden d-flex"><div class="rw-track d-flex align-items-center"><div class="position-relative rw-slide col-100 px-20 "><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="160984" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/91/151891-050-D4C0CD6F/Ice-cubes.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/281026/160984"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/91/151891-050-D4C0CD6F/Ice-cubes.jpg?w=300"><img src="https://cdn.britannica.com/91/151891-050-D4C0CD6F/Ice-cubes.jpg?w=300" alt="ice cubes" data-width="1100" data-height="1600" loading="eager"></picture><div class="position-absolute top-10 left-10 assembly-slide-tag rounded-lg">1 of 2</div><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/91/151891-050-D4C0CD6F/Ice-cubes.jpg" data-href="/media/1/281026/160984">ice cubes</a><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div><div class="position-relative rw-slide col-100 px-20 "><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="155360" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/79/149179-050-DC23D823/snowflake-threads-wool-coat.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/281026/155360"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/79/149179-050-DC23D823/snowflake-threads-wool-coat.jpg?w=300"><img src="https://cdn.britannica.com/79/149179-050-DC23D823/snowflake-threads-wool-coat.jpg?w=300" alt="snowflake on a wool coat" data-width="709" data-height="600" loading="eager"></picture><div class="position-absolute top-10 left-10 assembly-slide-tag rounded-lg">2 of 2</div><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/79/149179-050-DC23D823/snowflake-threads-wool-coat.jpg" data-href="/media/1/281026/155360">snowflake on a wool coat</a><span>Individual snowflake on the threads of a wool coat.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div></div><button disabled="true" class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_left"></span></button><button disabled="true" class="next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_right"></span></button></div><p class="topic-paragraph"><strong><span id="ref541036"></span>ice</strong>, <a href="https://www.britannica.com/science/solid-state-of-matter" class="md-crosslink autoxref " data-show-preview="true">solid</a> substance produced by the <a href="https://www.britannica.com/topic/freezing-food-preservation" class="md-crosslink autoxref " data-show-preview="true">freezing</a> of <span id="ref541037"></span><a href="https://www.britannica.com/science/water-vapor" class="md-crosslink ">water vapour</a> or liquid <a href="https://www.britannica.com/science/water" class="md-crosslink " data-show-preview="true">water</a>. At temperatures below 0 <a href="https://www.britannica.com/technology/Celsius-temperature-scale" class="md-crosslink autoxref " data-show-preview="true">°C</a> (32 °F), water vapour develops into <a href="https://www.britannica.com/science/frost-meteorology" class="md-crosslink autoxref " data-show-preview="true">frost</a> at ground level and <span id="ref541038"></span><a href="https://www.britannica.com/plant/snowflake-plant" class="md-crosslink " data-show-preview="true">snowflakes</a> (each of which consists of a single ice crystal) in clouds. Below the same temperature, liquid water forms a solid, as, for example, <a href="https://www.britannica.com/science/river" class="md-crosslink " data-show-preview="true">river</a> ice, <a href="https://www.britannica.com/science/sea-ice" class="md-crosslink " data-show-preview="true">sea ice</a>, <a href="https://www.britannica.com/science/hail-meteorology" class="md-crosslink " data-show-preview="true">hail</a>, and ice produced commercially or in household refrigerators.</p><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">Ice occurs on <a href="https://www.britannica.com/place/Earth" class="md-crosslink " data-show-preview="true">Earth</a>’s continents and surface waters in a variety of <span id="ref534397"></span><a href="https://www.britannica.com/science/ice-formation" class="md-crosslink " data-show-preview="true">forms</a>. Most notable are the continental glaciers (<a href="https://www.britannica.com/science/ice-sheet" class="md-crosslink " data-show-preview="true">ice sheets</a>) that cover much of <a href="https://www.britannica.com/place/Antarctica" class="md-crosslink " data-show-preview="true">Antarctica</a> and <a href="https://www.britannica.com/place/Greenland" class="md-crosslink " data-show-preview="true">Greenland</a>. Smaller masses of <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="perennial" href="https://www.merriam-webster.com/dictionary/perennial" data-type="MW">perennial</a> ice called ice caps occupy parts of Arctic <a href="https://www.britannica.com/place/Canada" class="md-crosslink " data-show-preview="true">Canada</a> and other high-latitude regions, and <a href="https://www.britannica.com/science/mountain-landform" class="md-crosslink " data-show-preview="true">mountain</a> <a href="https://www.britannica.com/science/glacier" class="md-crosslink " data-show-preview="true">glaciers</a> occur in more restricted areas, such as mountain valleys and the flatlands below. Other occurrences of ice on land include the different types of ground ice associated with <a href="https://www.britannica.com/science/permafrost" class="md-crosslink " data-show-preview="true">permafrost</a>—that is, permanently frozen <a href="https://www.britannica.com/science/soil" class="md-crosslink " data-show-preview="true">soil</a> common to very cold regions. In the oceanic waters of the polar regions, <a href="https://www.britannica.com/science/iceberg" class="md-crosslink " data-show-preview="true">icebergs</a> occur when large masses of ice break off from glaciers or ice shelves and drift away. The freezing of <a href="https://www.britannica.com/science/seawater" class="md-crosslink " data-show-preview="true">seawater</a> in these regions results in the formation of sheets of sea ice known as <a href="https://www.britannica.com/science/pack-ice" class="md-crosslink autoxref " data-show-preview="true">pack ice</a>. During the winter months similar ice bodies form on <a href="https://www.britannica.com/science/lake" class="md-crosslink " data-show-preview="true">lakes</a> and rivers in many parts of the world. This article treats the structure and properties of ice in general. Ice in lakes and rivers, glaciers, icebergs, pack ice, and permafrost are treated separately in articles under their respective titles. For a detailed account of the widespread occurrences of glacial ice during Earth’s past, <em>see</em> the articles <a href="https://www.britannica.com/science/geochronology" class="md-crosslink " data-show-preview="true">geochronology</a> and <a href="https://www.britannica.com/science/climate-meteorology" class="md-crosslink " data-show-preview="true">climate</a>. <em>See also</em> <a href="https://www.britannica.com/science/continental-landform" class="md-crosslink " data-show-preview="true">glacial landform</a> for the effects of glaciation.</p><span class="marker MOD2 mod-inline"></span></section> <span class="marker h2"></span><section data-level="1" id="ref65756"> <h2 class="h1">Structure</h2> <section data-level="2" id="ref65757"> <h2 class="h2">The <span id="ref534399"></span><a href="https://www.britannica.com/science/water" class="md-crosslink " data-show-preview="true">water</a> molecule</h2> <span class="marker PREMOD3 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="193668" data-asm-type="video"><div class="md-assembly-wrapper card-media" data-type="video" video-id="179991"><a data-id="179991" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/seawater-water-points/-193668"><img src="https://cdn.britannica.com/91/179991-138-CE02C903/seawater-water-points.jpg?w=800&h=450&c=crop" alt="Which has a lower freezing point, salt water or fresh water?" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/Lrz2m1E5.m3u8" } ], "image": "https://cdn.britannica.com/91/179991-138-CE02C903/seawater-water-points.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/BZ0dv3fR", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/iiCTMY18.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="179991">Which has a lower freezing point, salt water or fresh water?</span><span>Learn why fresh water and seawater have different freezing points.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/science/ice/images-videos">See all videos for this article</a></figcaption></figure></div></div><p class="topic-paragraph">Ice is the solid state of water, a normally liquid substance that freezes to the solid state at temperatures of 0 °C (32 °F) or lower and expands to the <a href="https://www.britannica.com/science/gas-state-of-matter" class="md-crosslink autoxref " data-show-preview="true">gaseous state</a> at temperatures of 100 °C (212 °F) or higher. Water is an extraordinary substance, anomalous in nearly all its physical and chemical properties and easily the most complex of all the familiar substances that are single-chemical <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="compounds" href="https://www.merriam-webster.com/dictionary/compounds" data-type="MW">compounds</a>. Consisting of two atoms of <span id="ref534400"></span><a href="https://www.britannica.com/science/hydrogen" class="md-crosslink " data-show-preview="true">hydrogen</a> (H) and one atom of <span id="ref534401"></span><a href="https://www.britannica.com/science/oxygen" class="md-crosslink " data-show-preview="true">oxygen</a> (O), the water <a href="https://www.britannica.com/science/molecule" class="md-crosslink autoxref " data-show-preview="true">molecule</a> has the <a href="https://www.britannica.com/science/chemical-formula" class="md-crosslink autoxref " data-show-preview="true">chemical formula</a> H<sub>2</sub>O. These three atoms are covalently bonded (i.e., their nuclei are linked by attraction to shared electrons) and form a specific structure, with the oxygen atom located between the two hydrogen atoms. The three atoms do not lie in a straight line, however. Instead, the hydrogen atoms are bent toward each other, forming an angle of about 105°.</p><span class="marker MOD3 mod-inline"></span> <span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">The three-dimensional structure of the water molecule can be pictured as a tetrahedron with an oxygen nucleus centre and four legs of high electron probability. The two legs in which the <span id="ref534402"></span><a href="https://www.britannica.com/science/hydrogen-bonding" class="md-crosslink " data-show-preview="true">hydrogen</a> nuclei are present are called <span id="ref534403"></span><a href="https://www.britannica.com/science/bonding-orbital" class="md-crosslink ">bonding orbitals</a>. Opposite the bonding orbitals and directed to the opposite corners of the tetrahedron are two legs of negative <a href="https://www.britannica.com/science/electric-charge" class="md-crosslink autoxref " data-show-preview="true">electrical charge</a>. Known as the <span id="ref534404"></span><a href="https://www.britannica.com/science/lone-pair" class="md-crosslink ">lone-pair</a> orbitals, these are the keys to water’s peculiar behaviour, in that they attract the hydrogen nuclei of <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="adjacent" href="https://www.merriam-webster.com/dictionary/adjacent" data-type="MW">adjacent</a> water molecules to form what are called hydrogen bonds. These bonds are not especially strong, but, because they orient the water molecules into a specific configuration, they significantly affect the properties of water in its solid, liquid, and gaseous states.</p><span class="marker MOD4 mod-inline"></span> <span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">In the <a href="https://www.britannica.com/science/liquid-state-of-matter" class="md-crosslink autoxref " data-show-preview="true">liquid state</a>, most water molecules are associated in a <span id="ref534405"></span><a href="https://www.britannica.com/science/polymer" class="md-crosslink " data-show-preview="true">polymeric</a> structure—that is, chains of molecules connected by weak hydrogen bonds. Under the influence of thermal agitation, there is a constant breaking and reforming of these bonds. In the gaseous state, whether <a href="https://www.britannica.com/science/steam" class="md-crosslink autoxref " data-show-preview="true">steam</a> or water vapour, water molecules are largely independent of one another, and, apart from collisions, interactions between them are slight. Gaseous water, then, is largely monomeric—i.e., consisting of single molecules—although there occasionally occur dimers (a union of two molecules) and even some trimers (a combination of three molecules). In the solid state, at the other extreme, water molecules interact with one another strongly enough to form an ordered crystalline structure, with each oxygen atom collecting the four nearest of its neighbours and arranging them about itself in a rigid lattice. This structure results in a more open assembly, and hence a lower <a href="https://www.britannica.com/science/density" class="md-crosslink autoxref " data-show-preview="true">density</a>, than the closely packed assembly of molecules in the liquid <a href="https://www.britannica.com/science/phase-state-of-matter" class="md-crosslink autoxref " data-show-preview="true">phase</a>. For this reason, water is one of the few substances that is actually less <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="dense" href="https://www.britannica.com/dictionary/dense" data-type="EB">dense</a> in solid form than in the liquid state, dropping from 1,000 to 917 kilograms per cubic metre. It is the reason why ice floats rather than sinking, so that, during the winter, it develops as a sheet on the surface of lakes and rivers rather than sinking below the surface and accumulating from the bottom.</p><a class="link-module shadow-sm d-block qa-quiz-module" href="/quiz/water-and-its-varying-forms" data-link-module-iframe-link=""> <img loading="lazy" src="https://cdn.britannica.com/02/157502-131-7C5D3A67/water-glass-background.jpg" alt="water glass on white background. (drink; clear; clean water; liquid)" class="rounded-sm mr-15" width="70" /> <div class="line-clamp clamp-5"> <div class="module-title bg-green">Britannica Quiz</div> <div class="font-weight-semi-bold mt-5">Water and its Varying Forms</div> </div> </a><div class="one-good-fact-module"> </div><span class="marker MOD5 mod-inline"></span> <span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">As water is warmed from the <a href="https://www.britannica.com/science/freezing-point" class="md-crosslink autoxref " data-show-preview="true">freezing point</a> of 0 to 4 °C (from 32 to 39 °F), it contracts and becomes denser. This initial increase in density takes place because at 0 °C a portion of the water consists of open-structured molecular arrangements similar to those of ice crystals. As the temperature increases, these structures break down and reduce their volume to that of the more closely packed polymeric structures of the liquid state. With further warming beyond 4 °C, the water begins to expand in volume, along with the usual increase in intermolecular <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="vibrations" href="https://www.britannica.com/dictionary/vibrations" data-type="EB">vibrations</a> caused by <a href="https://www.britannica.com/science/thermal-energy" class="md-crosslink autoxref " data-show-preview="true">thermal energy</a>.</p><span class="marker MOD6 mod-inline"></span> </section> </section><span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article></div> </div></div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":2,"pageId":281026,"pageLength":905,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-130/js/libs/jquery-3.5.0.min.js?v=3.130.38"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-130/dist/topic-page.js?v=3.130.38' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"D","adLeg":"D","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":true} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Ice | Definition, Structure, Properties, Freezing Point, & Facts | Britannica