a gentle introduction to the structure of water

A Gentle Introduction to the Structure of Water

68 PowerPlant Chemistry 2007, 9(2)

Stephen Lower

ABSTRACT

Basic chemical theory predicts that a substancewhose molecules are made up of just three lightweightatoms could not possibly exist as a liquid under ordi-nary conditions. This is just one of the "anomalous"properties that the structural unit H2O confers on theliquid we know as water, and which enable thisremarkable substance to play a central role in shapingboth our planet and the living organisms on it.

This article attempts to show how the nature of water-the-molecule leads to higher-level structural elementsthat give water-the-substance its unique properties.The essential role of water in the human body hascaused some science-naive seekers-of-health to strayinto the realm of pseudoscience; sales of miraclewater-treatment devices, homeopathic remedies andvarious fictional "structured" waters are now a thrivingindustry.

INTRODUCTION

Water has long been known to exhibit many physical prop-erties that distinguish it from other small molecules ofcomparable mass. Chemists refer to these as the "anom-alous" properties of water, but they are by no means mys-terious; all are entirely predictable consequences of theway the size and nuclear charge of the oxygen atom con-spire to distort the electronic charge clouds of the atoms ofother elements when these are chemically bonded to theoxygen.

A covalent chemical bond consists of a pair of electronsshared between two atoms. In the water molecule H2O, thesingle electron of each H is shared with one of the sixouter-shell electrons of the oxygen, leaving four electronswhich are organized into two nonbonding pairs. Thus theoxygen atom is surrounded by four electron pairs thatwould ordinarily tend to arrange themselves as far fromeach other as possible in order to minimize repulsionsbetween these clouds of negative charge. This would ordi-narily result in a tetrahedral geometry in which the anglebetween electron pairs (and therefore the H—O—H bond

angle) is 109°. However, because the two nonbondingpairs remain closer to the oxygen atom, these exert astronger repulsion against the two covalent bonding pairs,effectively pushing the two hydrogen atoms closertogether. The result is a distorted tetrahedral arrangementin which the H—O—H angle is 104.5° (Figure 1).

Because molecules are smaller than light waves, they can-not be observed directly, and must be "visualized" by alter-native means. The two computer-generated images of theH2O molecule shown in Figure 2 come from calculationsthat model the electron distribution in molecules. The outerenvelopes show the effective "surface" of the molecule asdefined by the extent of the electron cloud.

The H2O molecule is electrically neutral, but the positiveand negative charges are not distributed uniformly. This isshown clearly by the gradation in color from green to pur-ple in Figure 2 at the right. The electronic (negative)charge is concentrated at the oxygen end of the molecule,owing partly to the nonbonding electrons (solid blue circlesin Figure 3), and to oxygen's high nuclear charge, whichexerts stronger attractions on the electrons. This chargedisplacement constitutes an electric dipole, representedby the arrow at the bottom; you can think of this dipole asthe electrical "image" of a water molecule.

As we all learned in school, opposite charges attract, sothe partially positive hydrogen atom on one water mole-cule is electrostatically attracted to the partially negativeoxygen on a neighboring molecule. This process is called(somewhat misleadingly) hydrogen bonding. Notice thatthe hydrogen bond shown in Figure 4 by the dashed line issomewhat longer (117 pm) than the covalent O—H bond(99 pm). This means that it is considerably weaker; it is soweak, in fact, that a given hydrogen bond cannot survivefor more than a tiny fraction of a second.


© 2007 by PowerPlantChemistry GmbH. All rights reserved. Figure 1: Water molecule – a covalent bond.

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69PowerPlant Chemistry 2007, 9(2)

HOW CHEMISTS THINK ABOUT WATER

The nature of liquid water and how the H2O moleculeswithin it are organized and interact are questions that haveattracted the interest of chemists for many years. There isprobably no liquid that has received more intensive study,and there is now a huge literature on this subject.

The following facts are well established:

• H2O molecules attract each other through the specialtype of dipole-dipole interaction known as hydrogenbonding.

• A hydrogen-bonded cluster in which four H2Os arelocated at the corners of an imaginary tetrahedron is anespecially favorable (low-potential energy) configura-tion, but...

• The molecules undergo rapid thermal motions on a timescale of picoseconds (10–12 s), so the lifetime of anyspecific clustered configuration will be fleetingly brief.

A variety of techniques including infrared absorption, neu-tron scattering, and nuclear magnetic resonance havebeen used to probe the microscopic structure of water.The information garnered from these experiments andfrom theoretical calculations has led to the development ofaround twenty "models" that attempt to explain the struc-ture and behavior of water. More recently, computer simu-lations of various kinds have been employed to explorehow well these models are able to predict the observedphysical properties of water.

This work has led to a gradual refinement of our viewsabout the structure of liquid water, but it has not producedany definitive answer. There are several reasons for this,but the principal one is that the very concept of "structure"(and of water "clusters") depends on both the timeframeand volume under consideration. Thus, questions of thefollowing kinds are still open:

• How do you distinguish the members of a "cluster" fromadjacent molecules that are not in that cluster?

• Since individual hydrogen bonds are continually break-ing and re-forming on a picosecond time scale, dowater clusters have any meaningful existence overlonger periods of time? In other words, clusters are tran-sient, whereas "structure" implies a molecular arrange-ment that is more enduring. Can we then legitimatelyuse the term "clusters" in describing the structure ofwater?

• The possible locations of neighboring molecules arounda given H2O are limited by energetic and geometric con-siderations, thus giving rise to a certain amount of"structure" within any small volume element. It is notclear, however, to what extent these structures interactas the size of the volume element is enlarged. And asmentioned above, to what extent are these structuresmaintained for periods longer than a few picoseconds?

The view first developed in the 1950s that water is a col-lection of "flickering clusters" of varying sizes (Figure 5)has gradually been abandoned as being unable to accountfor many of the observed properties of the liquid. The cur-rent thinking, influenced greatly by molecular modelingsimulations beginning in the 1980s, is that on a very shorttime scale (less than a picosecond), water is more like a"gel" consisting of a single, huge hydrogen-bonded clus-ter. On a 10–12 s – 10–9 s time scale, rotations and otherthermal motions cause individual hydrogen bonds to breakand re-form in new configurations, inducing ever-changinglocal discontinuities whose extent and influence dependon the temperature and pressure. It is quite likely that oververy small volumes, localized ( H2O)n polymeric clustersmay have a fleeting existence, and many theoretical calcu-lations have been made showing that some combinations

Figure 2: Electron distribution in the water molecule(computer-generated images).

Figure 3: Water molecule – a dipole.

See http://www.lsbu.ac.uk/water/molecule.htmlfor more information on the above model.

Figure 4: Hydrogen bonding.

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are more stable than others. While this might prolong theirlifetimes, it does not appear that they remain intact longenough to be detected as directly observable entities inordinary bulk water at normal pressures.

Think of liquid water as a seething mass of H2O moleculesin which hydrogen-bonded clusters are continually form-ing, breaking apart, and re-forming. Theoretical modelssuggest that the average cluster may encompass as manyas 90 H2O molecules at 0 °C, so that very cold water canbe thought of as a collection of ever-changing ice-likestructures. At 70 °C, the average cluster size is probablyno greater than about 25.

Professor Martin Chaplin of the London South BankUniversity has reviewed much of the existing literature onwater clustering, and has recently proposed an icosohe-dral clustering model (see also http://www.lsbu.ac.uk/water/intro.html) in which twenty 14-molecule tetrahedralunits form an icosohedron containing a total of 280 H2Ounits. This model is consistent with X-ray diffraction dataand is able to explain all of the unusual properties of water(Figure 6).

It must be emphasized that no stable clustered unit orarrangement has ever been isolated or identified in purebulk liquid water. A 2006 report (see http://www.lbl.gov/Science-Articles/Archive/PBD-water-controversy.html)suggests that a simple tetrahedral arrangement is the onlylong-range structure that persists at time scales of apicosecond or beyond.

Water clusters are of considerable interest as models forthe study of water and water surfaces, and many articleson them are published every year. Some notable workreported in 2004 extended our view of water to the fem-tosecond time scale. The principal finding was that 80 %

of the water molecules are bound in chain-like fashion toonly two other molecules at room temperature, thus sup-porting the prevailing view of a dynamically changing, dis-ordered water structure.

Liquid & Solid Water

Ice, like all solids, has a well-defined structure: each watermolecule is surrounded by four neighboring H2O s(Figure 7). Two of these are hydrogen-bonded to the oxy-gen atom on the central H2O molecule, and each of thetwo hydrogen atoms is similarly bonded to another neigh-boring H2O.

The hydrogen bonds are represented by the dashed linesin the two-dimensional schematic diagram. In reality, thefour bonds from each O atom point toward the four cor-ners of a tetrahedron centered on the O atom. This basicassembly repeats itself in three dimensions to build the icecrystal.

When ice melts to form liquid water, the uniform three-dimensional tetrahedral organization of the solid breaksdown as thermal motions disrupt, distort, and occasionallybreak hydrogen bonds. The methods used to determinethe positions of molecules in a solid do not work with liq-uids, so there is no unambiguous way of determining thedetailed structure of water. Figure 8 is probably typical ofthe arrangement of neighbors around any particular H2Omolecule, but very little is known about the extent to whichan arrangement like this gets propagated to more distantmolecules.

Figure 9 shows three-dimensional views of a typical localstructure of liquid water and of ice. Notice the greateropenness of the ice structure, which is necessary toensure the strongest degree of hydrogen bonding in a uni-



Figure 5: Water cluster diagram. Figure 6: Chaplin's clustering model.

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form, extended crystal lattice. The more crowded and jum-bled arrangement in liquid water can be sustained only bythe greater amount of thermal energy available above thefreezing point.

The Anomalous Properties of Water

Water is almost unique among the more than 15 millionknown chemical substances in that its solid form is lessdense than the liquid.

Figure 10 shows how the volume of water varies with thetemperature; the large increase (about 9 %) on freezingshows why ice floats on water and why pipes burst whenthey freeze. The expansion between –4 °C and 0 °C is dueto the formation of larger clusters. Above 4 °C, thermalexpansion sets in as thermal vibrations of the O—H bondsbecome more vigorous, tending to shove the moleculesfarther apart.

The other widely cited anomalous property of water is itshigh boiling point. As Figure 11 shows, a molecule as light

as H2O "should" boil at around –90 °C; that is, it shouldexist in the world as a gas rather than a liquid, if hydrogenbonding were not present. Notice that hydrogen bonding isalso observed with fluorine and nitrogen.

There are many other anomalies of water – some of themrather esoteric (see http://www.lsbu.ac.uk/water/anmlies.html).

Surface Tension and Wetting

Have you ever watched an insect walk across the surfaceof a pond (Figure 12)? The water strider takes advantageof the fact that the water surface acts like an elastic filmthat resists deformation when a small weight is placed onit. (If you are careful, you can also "float" a small paper clipor steel staple on the surface of water in a cup.) This is alldue to the surface tension of the water. A molecule withinthe bulk of a liquid experiences attractions to neighboringmolecules in all directions, but since these average out tozero, there is no net force on the molecule. For a moleculeat the surface, the situation is quite different; it experiences

Figure 7: Ice structure (a two-dimensional schematicdiagram).

Figure 8: Arrangement of neighbors around anyparticular H2O molecule.

Figure 9: Three-dimensional views of a typical local structure of liquid water (right) and of ice (left).

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forces only sideways and downward, and this is what cre-ates the stretched-membrane effect.

The distinction between molecules located at the surfaceand those deep inside is especially prominent in H2O,owing to the strong hydrogen-bonding forces. The differ-ence between the forces experienced by a molecule at thesurface and one in the bulk liquid gives rise to the liquid'ssurface tension.

Figure 13 highlights two H2O molecules, one at the sur-face, and the other in the bulk of the liquid. The surfacemolecule is attracted to its neighbors below and to eitherside, but there are no attractions pointing in the 180° solidangle above the surface. As a consequence, a molecule atthe surface will tend to be drawn into the bulk of the liquid.But since there must always be some surface, the overalleffect is to minimize the surface area of a liquid. The geo-metric shape that has the smallest ratio of surface area tovolume is the sphere, so very small quantities of liquidstend to form spherical drops. As the drops get bigger, theirweight deforms them into the typical tear shape.

Wetting Take a plastic mixing bowl from yourkitchen, and splash some water around in it. You will prob-ably observe that the water does not cover the inside sur-face uniformly, but remains dispersed into drops. Thesame effect is seen on a dirty windshield; turning on thewipers simply breaks hundreds of drops into thousands.By contrast, water poured over a clean glass surface willwet it, leaving a uniform film.

When a liquid is in contact with a solid surface, its behav-ior depends on the relative magnitudes of the surface ten-sion forces and the attractive forces between the mole-cules of the liquid and of those comprising the surface(Figure 14). If an H2O molecule is more strongly attractedto its own kind, then surface tension will dominate,increasing the curvature of the interface. This is what hap-pens at the interface between water and a hydrophobicsurface such as a plastic mixing bowl or a windshieldcoated with oily material. A clean glass surface, by con-trast, has OH– groups sticking out of it which readily attachto water molecules through hydrogen bonding; this causesthe water to spread out evenly over the surface, or to wet

Figure 10: Specific volume of water as a function oftemperature.

Figure 11: Boiling point of water and some otherhydrides.

Figure 12: Water measurer (Hydrometra stagnorum). Figure 13: Surface tension of water.

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it. A liquid will wet a surface if the angle at which it makescontact with the surface is more than 90°. The value of thiscontact angle can be predicted from the properties of theliquid and solid separately.

If we want water to wet a surface that is not ordinarily wet-table, we add a detergent to the water to reduce its surfacetension. A detergent is a special kind of molecule in whichone end is attracted to H2O molecules but the other end isnot; the latter ends stick out above the surface and repeleach other, canceling out the surface tension forces due tothe water molecules alone.

"PURE" WATER

To a chemist, the term "pure" has meaning only in the con-text of a particular application or process. The distilled orde-ionized water we use in the laboratory contains dis-solved atmospheric gases and occasionally some silica,but their small amounts and relative inertness make theseimpurities insignificant for most purposes. When water ofthe highest obtainable purity is required for certain types ofexacting measurements, it is commonly filtered, de-ion-ized, and triple-vacuum distilled. But even this "chemicallypure" water is a mixture of isotopic species: there are twostable isotopes of both hydrogen (1H and 2H, oftendenoted by D) and oxygen (16O and 18O), which give rise tocombinations such as H2

18O, HDO, etc., all of which arereadily identifiable in the infrared spectra of water vapor.(Interestingly, the ratio of 18O/16O in water varies enoughfrom place to place that it is now possible to determine thesource of a particular water sample with some precision.)And to top this off, the two hydrogen atoms in water con-tain protons whose magnetic moments can be parallel or

antiparallel, giving rise to ortho- and para-water, respec-tively. The two forms are normally present in an ortho/pararatio of 3:1.

It has recently been found (Yamashita et al., 2003) thatfreshly distilled water takes a surprisingly long time toequilibrate with the atmosphere, that it undergoes largefluctuations in pH and redox potential, and that theseeffects are greater when the water is exposed to a mag-netic field. The reasons for this behavior are not clear, butone possibility is that dissolved O2 molecules, which areparamagnetic, might be involved.

Drinking Water

Our ordinary drinking water, by contrast, is never chemi-cally pure, especially if it has been in contact with sedi-ments. Groundwaters (from springs or wells) always con-tain ions of calcium and magnesium, and often iron andmanganese as well; the positive charges of these ions arebalanced by the negative ions carbonate/bicarbonate, andoccasionally some chloride and sulfate. Groundwaters insome regions contain unacceptably high concentrations ofnaturally occurring toxic elements such as selenium andarsenic.

One might think that rain or snow would be exempt fromcontamination, but when water vapor condenses out ofthe atmosphere, it always does so on a particle of dust,which releases substances into the water, and even thepurest air contains carbon dioxide, which dissolves to formcarbonic acid. Except in highly polluted atmospheres, theimpurities picked up by snow and rain are too minute to beof concern.

Various governments have established upper limits on theamounts of contaminants allowable in drinking water; thebest known of these are the U.S. Environmental ProtectionAgency Drinking Water Standards (see http://www.epa.gov/safewater/contaminants/index.html).

One occasionally hears that waters containing unusuallysmall amounts of minerals, and distilled water particularly,are unhealthy because they "leach out" required mineralsfrom the body. Such claims are unfounded; the fact is thatcell walls contain one-way channels that utilize metabolicenergy to actively transport needed ions against what isoften a substantial concentration gradient (see http://www.northland.cc.mn.us/biology/Biology1111/animations/active1.html). (See http://www.biologie.uni-hamburg.de/b-online/e22/22d.htm for more information on this.)

STRUCTURED WATER AND BIOWATER

As we explained above, bulk liquid water consists of aseething mass of various-sized chain-like groups thatflicker in and out of existence on a time scale of picosec-onds. But in the vicinity of a solid surface or of another



Figure 14: Wetting of surfaces.

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molecule or ion that possesses an unbalanced electriccharge, water molecules can become oriented and some-times even bound into relatively stable structures.

Water in Ionic Hydration Shells

Water molecules interact strongly with ions, which areelectrically charged atoms or molecules. Dissolution ofordinary salt (NaCl) in water yields a solution containing theions Na+ and Cl–. Owing to its high polarity, the H2O mole-cules closest to the dissolved ion are strongly attached toit, forming what is known as the inner or primary hydrationshell. Positively charged ions such as Na+ attract the neg-ative (oxygen) ends of the H2O molecules, as shown inFigure 15. The ordered structure within the primary shellcreates, through hydrogen bonding, a region in which thesurrounding waters are also somewhat ordered; this is theouter hydration shell, or cybotactic region.

Some recent experiments (see http://www-als.lbl.gov/als/science/sci_archive/67orbitmix.html) have revealed adegree of covalent bonding between the d-orbitals of tran-sition metal ions and the oxygen atoms of water moleculesin the inner hydration shell.

Bound Water in Biological Systems

It has long been known that the intracellular water veryclose to any membrane or organelle (sometimes called vic-inal water) is organized very differently from bulk water,and that this structured water plays a significant role ingoverning the shape (and thus biological activity) of largefolded biopolymers. It is important to bear in mind, how-

ever, that the structure of the water in these regions isimposed solely by the geometry of the surrounding hydro-gen bonding sites.

Water can hydrogen-bond not only to itself, but also to anyother molecules that have -OH or -NH2 units hanging off ofthem. This includes simple molecules such as alcohols,surfaces such as glass, and macromolecules such as pro-teins. The biological activity of proteins (of which enzymesare an important subset) is critically dependent not only ontheir composition but also on the way these huge mole-cules are folded; this folding involves hydrogen-bondedinteractions with water, and also between different parts ofthe molecule itself. Anything that disrupts these intramole-cular hydrogen bonds will denature the protein and destroyits biological activity. This is essentially what happenswhen you boil an egg; the bonds that hold the egg whiteprotein in its compact folded arrangement break apart sothat the molecules unfold into a tangled, insoluble masswhich, like Humpty Dumpty, cannot be restored to its orig-inal form. Note that hydrogen bonding need not alwaysinvolve water; thus the two parts of the DNA double helixare held together by H—N—H hydrogen bonds.

Figure 16, taken from the work of William Royer Jr. of theUniversity of Massachusetts Medical School, shows thewater structure (small circles) that exists in the spacebetween the two halves of a kind of dimeric hemoglobin.The thin dotted lines represent hydrogen bonds. Owing tothe geometry of the hydrogen-bonding sites on the hemeprotein backbones, the H2O molecules within this regionare highly ordered; the local water structure is stabilized bythese hydrogen bonds, and the resulting water cluster inturn stabilizes this particular geometric form of the hemo-

Figure 15: Water hydration shells. Figure 16: Intracellular water in biopolymers.

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globin dimer. More diagrams, with commentary, can befound on Prof. Royer's Web site at http://www.umassmed.edu/bmp/faculty/royer.cfm?start=Figures.

In 2003, some chemists in India (Neogi, S., Bharadvaj, P.K., 2005) found that a suitable molecular backbone(Figure 17) can even cause water molecules to form a"thread" that can snake its way though the more openspace of the larger molecules. What all of these examplesshow is that water can have highly organized local struc-tures when it interacts with molecules capable of imposingthese structures on the water.

"Clustered," "Unclustered" and Other Structure-Altered Waters

The "alternative" health market is full of goofy products(see http://www.chem1.com/CQ/clusqk.html) which pur-port to alter the structure of water by stabilizing groups ofH2O molecules into permanent clusters of 4–8 molecules,or alternatively, to break up what they claim are the largerclusters (usually 10–15 molecules) that they say normallyexist in water. The object in either case is to promote theflow of water into the body's cells ("cellular hydration")(see http://www.chem1.com/CQ/aquaporin.html for com-ments on this). This is of course utter nonsense; there is no

credible scientific evidence for any of these claims, manyof which verge on the bizarre. There are even some scien-tifically absurd U.S. Patents (http://www.chem1.com/CQ/clusterpats.html) for the manufacture of so-called"Clustered Water™." At least 20 nostrums of this kind areoffered to the scientifically naive public through hundredsof Web sites and late-night radio "infomercials." None ofthese claims is supported by credible evidence (Figure 18).

Does Water Have "Memory"?

According to modern-day proponents of homeopathy, itmust. Homeopathic remedies are made by diluting solu-tions of various substances so greatly that not even a sin-gle molecule of the active substance can be expected tobe present in the final medication. Now that even thehomeopaths have come to accept this fact, they explainthat the water somehow retains the "imprint" or "memory"of the original solute.

Some references (mostly skeptical) on homeopathy maybe found at http://www.phy.syr.edu/courses/modules/PSEUDO/pseu do_main.html#homeopathy.

In 1985, the late Jacques Benveniste, a French biologist,conducted experiments that purported to show that a cer-tain type of cellular immune response could be broughtabout by an anti-immunoglobulin agent that had beendiluted to such an extent that it is highly unlikely that evenone molecule of this agent remained in the aqueous solu-tion. He interpreted this to indicate that water could some-how retain an impression, or "memory," of a solute thathad been diluted out of existence. This result was immedi-ately taken by believers in homeopathy as justification fortheir dogma that similarly diluted remedies could be effec-tive as alternative medical agents. The consensus amongchemists is that any temporary disruption of the waterstructure by a dissolved agent would disappear within afraction of a nanosecond after its removal by dilution,owing to the vigorous thermal motions of the water mole-cules. Benveniste's results have never been convincinglyreplicated by other scientists (see http://www.angelfire.com/falcon/starbird/technopagan/index.blog?entry_id=300227).

REFERENCES

Yamashita, M., Duffield, C., Tiller, W. A., Langmuir 2003,19(17), 6851.

Neogi, S., Bharadvaj, P. K., Inorg. Chem. 2005, 44(4), 816.

The Mystery, Art and Science of Water http://witcombe.sbc.edu/water/chemistryproperties.htmlThis site provides a wonderful view of water in all the manyways it impacts upon the multiple facets of our culture.Highly recommended.

Figure 17: Water structure (small circles) that exists in thespace between the two halves of a kind ofdimeric hemoglobin.

Figure 18:

From the history ofan "alternative"health market.

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Water Structure and Propertieshttp://www.lsbu.ac.uk/water/index2.htmlThis is a Web site developed by Martin Chaplin at SouthBank University in England. It is a scientifically sound, welllaid-out collection of articles on water and its structurewhich should answer any of your questions.

Does Hot Water Freeze Faster Than Cold Water?http://www.answerbag.com/q_view/11063

Liu, K., Cruzan, J. D., Saykally, R. J., Science 1996, 271,929.A summary of experimental data on the structures, ener-getics and dynamics of small clusters, and comparisonswith theoretical predictions.

"Water Buckyballs": Chemical, Catalytic and CosmicImplications, 1998. http://www.watercluster.comThis rather technical paper by Keith Johnson of theMassachusetts Institute of Technology explores the quan-tum theory and far-IR spectra of water clusters and specu-lates on their role in cosmochemistry.

The Structure of Ideal Liquid Waterhttp://web.archive.org/web/20021207085952/http://www.morenos.com/waterstructure.htmlA well-organized but rather technical Web site by GregoryMoreno. It includes an extensive bibliography of scientificarticles on water structure from 1915 through 1992.

Cell-Associated Water (Eds.: W. Drost-Hansen, J. Clegg),1979. Academic Press, New York, NY, U.S.A.This is a collection of 11 papers given at a conference in1976. It predates the availability of modern laser-basedmethods of examining water structure, but contains a lot ofindirect observations and nuclear magnetic resonanceresults.

Water on Earth: The Hydrosphere and the Oceanshttp://www.chem1.com/acad/webtext/geochem/05txt.htmlThis site, from the author's former course in EnvironmentalChemistry, presents a general survey.

Why is Water Blue?http://www.dartmouth.edu/~etrnsfer/water.htm(reproduced from Braun, C. L., Smirnov, S. N., J. Chem.Edu. 1993, 70(8), 612)It's all about O–H bond stretching! A more technical site.

And finally, for a darker view of water, see the Ban DHMOpage at http://www.dhmo.org/.

THE AUTHOR

Stephen Lower (B.S., Physical Chemistry, University ofCalifornia, Berkeley, CA, Ph.D., Physical Chemistry, Uni-versity of British Columbia, Vancouver, Canada) is a retiredmember of the Chemistry Department at Simon FraserUniversity in Vancouver, Canada. He now does consultingwork for educational publishers and manages Web sitesdevoted to chemistry education and water-related pseu-doscience.

CONTACT

Stephen LowerDepartment of ChemistrySimon Fraser UniversityBurnaby BC V5A 1S6Canada

E-mail: [email protected]

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a gentle introduction to the structure of water

Documents

water molecule h2o

nature of water

anglebetween electron

electron pairs thatwould

essential role of water

thesingle electron

electron distribution

electron cloud