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electron domain geometry and molecular geometry

The equatorial position does a better job of this, since only two bonding pairs of electrons are at approximately $$90^\text{o}$$ away from three bonding pairs. General Chemistry: Electron Domain Geometry versus Molecular Geometry. 30 seconds . The electron-domain geometry and molecular geometry of iodine trichloride are _____ and _____, respectively. The Boron atom has only three pairs of valence shell electrons in $$\ce{BCl_3}$$. For reasons that will become clear, extension of this model implies that a better name is the Electron Domain (ED) Theory. Electron domain is used in VSEPR theory to determine the molecular geometry of a molecule. Missed the LibreFest? The second figure serves as a visual aid for the table. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. Therefore, our Electron Domain model assumptions are consistent with the observed geometry of $$\ce{SF_4}$$. The $$\ce{Cl-X-Cl}$$ bond angles in the two molecules shown in Figure 7.5 are identical, because the bond angle is determined by the repulsion of the two $$\ce{Cl}$$ atoms, which is identical in the two molecules. Thanks for writing such a complete ..And,I wantn’t to miss them.Thank you for sharing.. Good evening .. (a).there are no lone pairs on the central atom. A quick explanation of the molecular geometry of O2 including a description of the O2 bond angles. Figure 7.1: Molecular structures of common molecules. :) The electron-domain geometry and molecular geometry of iodine trichloride are _____ and _____, respectively. This agrees very closely with the observed bond angles. Actually, I am fond of reading online punjabi news. Sulfur tetrafluoride, $$\ce{SF_4}$$, is a particularly interesting example, shown in Figure 7.4. 7: Molecular Geometry and Electron Domain Theory, [ "article:topic", "Trigonal Planar", "trigonal bipyramidal", "Lewis structure model", "diatomic molecule", "polyatomic molecule", "lone pairs", "valence shell electron pair repulsion theory", "VSEPR", "electron domain theory", "ED", "expanded valence", "octahedron", "showtoc:no" ], 6: Covalent Bonding and Electron Pair Sharing, 8: Molecular Structure and Physical Properties, Observation 2: Molecules with Double or Triple Bonds, Observation 3: Distortions from Expected Geometries, valence shell electron pair repulsion theory, information contact us at info@libretexts.org, status page at https://status.libretexts.org. By contrast, in ethene, $$\ce{C_2H_4}$$, each $$\ce{H-C-H}$$ bond angle is $$116.6^\text{o}$$, and each $$\ce{H-C-C}$$ bond angle is $$121.7^\text{o}$$. I think this is an interesting read based on the molecular geometry principal. Create your own unique website with customizable templates. Write if the molecule is… Each carbon atom in this molecule is surrounded by four pairs of electrons, all of which are involved in bonding, i.e. We have developed the Electron Domain model to this point only for geometries of molecules with four pairs of valence shell electrons. The term electron geometry refers to the name of the geometry of the electron pair/groups/domains on the central atom, whether they are bonding electrons or non-bonding electrons. (See also Figure 7.1.) At a more detailed level, the geometry includes the lengths of all of these bonds, that is, the distances between the atoms which are bonded together, and the angles between pairs of bonds. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. These deviations will be discussed later.). Repeat this argument to find the expected arrangements for two, three, five, and six points on the surface of the ball. We begin by assuming a Lewis structure model for chemical bonding based on valence shell electron pair sharing and the octet rule. One way to understand this result is based on the mutual repulsion of the negative charges on the valence shell electrons. Predict the electron and molecular geometry for a molecule with 6 bindings domains and a single lone pair. Hence, phosphorus exhibits what is called an expanded valence in $$\ce{PCl_5}$$. For example, sulfur dioxide, SO2, electron-domain geometry is trigonal planar. It is the 3D arrangement of all the atoms in a particular molecule. Molecular Geometry 1 Molecular Geometry How can molecular shapes be predicted using the VSEPR theory? We find that the three points form an equilateral triangle in a plane with the center of the sphere, so Electron Domain is again in accord with the observed geometry. Looking at the table, when we go from AX2, AX3 and all the way down to AX2N2, we will find out that the bond angle is … It helps understand how different electron groups are arranged in a molecule. trigonal bipyramidal. In molecules with more than three atoms, there are many more possible geometries. Recall that each $$\ce{H-C-H}$$ bond angle is $$116.6^\text{o}$$ and each $$\ce{H-C-C}$$ bond angle is $$121.7^\text{o}$$, whereas the Electron Domain theory prediction is for bond angles exactly equal to $$120^\text{o}$$. The required geometry can again be found by trying to place five points on the surface of a sphere with maximum distances amongst these points. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. This is true for determining electron domain geometry (EDG). Thus, ethene and ethane have very different geometries, despite the similarities in their molecular formulae. To account for this structure, we first prepare a Lewis structure. This model also works well in predicting the bond angles in ethane. The geometry of a molecule is important in determining its properties like color, magnetism, reactivity, polarity, etc. For methane and ethane, these four electron pairs are all shared with adjacent bonded atoms, whereas in ammonia or water, one or two (respectively) of the electron pairs are not shared with any other atom. Let's go and check and make sure that that is true. As an example of a molecule with an atom with less than an octet of valence shell electrons, we consider boron trichloride, $$\ce{BCl_3}$$. As such, this model of molecular geometry is often referred to as the valence shell electron pair repulsion (VSEPR) theory. I was very impressed to read your article, very nice and helpful. Joseph Aidan It has 6 electron domains. "above" the sulfur) or on the equator of the bipyramid (i.e. The convention is to indicate the number of bonding electron pairs by the capital letter X, the number of lone electron pairs by the capital letter E, and the capital letter A for the central atom of the molecule (AX n E m). Assess the accuracy of the following reasoning and conclusions: Phosphorus Pentafluoride on Wikipedia. If two EDs are lone pairs, we have to decide among the following options: both axial, both equatorial, or one axial and one equatorial. A table of geometries using the VSEPR theory can facilitate drawing and understanding molecules. For example, the molecular geometry of water for is bent because of the lone pairs, while the EDG is tetrahedral. Molecular geometry, on the other hand, determines the shape of a molecule and it is the three-dimensional structure of atoms in a molecule. octahedral. Recall: The electron-domain geometry of a molecule depends on the number of electron groups (bonding pair electrons + lone pair electrons) surrounding the central atom. Second, $$\ce{SF_6}$$ is a fairly unreactive gaseous compound in which all six fluorine atoms are bonded to the central sulfur atom. The figure below illustrates the molecular geometries of AB x molecules in which all the electron domains are bonds- that is, there are no lone pairs on the central atom. All six atoms of ethene lie in the same plane. Therefore, the powerful tendency of the two electrons in the pair to repel one another must be significantly offset by the localization of these electrons between the two nuclei which share them. We can straightforwardly conclude from these observations that the lone pairs of electrons must produce a greater repulsive effect than do the bonded pairs. VSEPR is based on the idea that the “groups” or “clouds” of electrons surrounding an atom will adopt an arrangement that minimizes the repulsions between them. Electron geometry teaches us about the arrangement of different electron groups. To apply our Electron Domain model to understand this geometry, we must place six points, representing the six electron pairs about the central $$\ce{S}$$ atom, on the surface of a sphere with maximum distances between the points. The electron domain geometry for PF6- is octahedral and the molecular geometry is octahedral. Explain why arranging points on the surface of a sphere can be considered equivalent to arranging electron pairs about a central atom. It is interesting to note that some molecular geometries ($$\ce{CH_4}$$, $$\ce{CO_2}$$, $$\ce{HCCH}$$) are exactly predicted by the Electron Domain model, whereas in other molecules, the model predictions are only approximately correct. On the other hand, molecular geometry is determined by the arrangement of the bonds present in the molecule. The relationship between bonding, structure, and properties is comparatively simple in diatomic molecules, which contain two atoms only, e.g. The valence shell electron-pair repulsion (VSEPR) model is used to predict the shapes of molecules and polyatomic ions. Carson. Explain how a comparison of the geometries of $$\ce{H_2O}$$ and $$\ce{CH_4}$$ leads to a conclusion that lone pair electrons produce a greater repulsive effect than do bonded pairs of electrons. very interesting topics, I hope the incoming comments and suggestion are equally positive. We should expect that the properties of molecules, and correspondingly the substances which they comprise, should depend on the details of the structure and bonding in these molecules. Electron Pair Geometry vs Molecular Geometry . "beside" the sulfur). The bond angles are compressed relative tothose in a perfect trigonal bipyramid due to lone pairs spreading out more in space than bonded pairs. Notice that, in the two molecules with no lone pairs, all bond angles are exactly equal to the tetrahedral angle, whereas the bond angles are only close in the molecules with lone pairs. SURVEY . Why? The concept that lone pair electrons produce a greater repulsive effect than do bonded pairs can be used to understand other interesting molecular geometries. Applying our Electron Domain model, we expect the five valence shell electron pairs to spread out optimally to minimize their repulsions. When search engines were during their infancy phase, these classic SEO techniques helped a lot of websites in ranking higher among their competitors. For example, we find that in water, $$\ce{H_2O}$$, the two hydrogens are bonded to the oxygen and each $$\ce{O-H}$$ bond length is $$95.72 \: \text{pm}$$ (where $$1 \: \text{pm} = 10^{-12} \: \text{m}$$). The VSEPR notation for these molecules are AX n. "A" represents the central atom and n represents the number of bonds with the central atom. SN (C) = 4 atoms + 0 lone pairs = 4 SN (N) = 3 atoms + 1 lone pair = 4 This corresponds to a tetrahedral electron geometry: However, their molecular geometries are different. very nice and helpful. Thus, in ammonia, the three bonded pairs of electrons are forced together slightly compared to those in methane, due to the greater repulsive effect of the lone pair. There are many types of geometries. The lone pairs must be taken account when determining molecular geometry. This observed geometry can be understood by re-examining the Lewis structure. Minimizing the repulsion between these two domains forces the oxygen atoms to directly opposite sides of the carbon, producing a linear molecule. Watch the recordings here on Youtube! Recall that, although there are four electron pairs about each carbon atom, two of these pairs form a double bond between the carbon atoms. Molecular geometries (linear, trigonal, tetrahedral, trigonal bipyramidal, and octahedral) are determined by the VSEPR theory. A little experimentation reveals that this can be achieved by placing the five points to form a trigonal bipyramid. A covalent chemical bond is formed when the two bonded atoms share a pair of valence shell electrons between them. To preserve the double bond, we must assume that the two electron pairs in the double bond remain in the same vicinity. A bit of experimentation reveals that these four points must sit at the corners of a tetrahedron, an equilateral triangular pyramid, as may be seen in Figure 7.2a. We can assume, however, that a pair of electrons shared by two atoms must be located somewhere between the two nuclei, otherwise our concept of "sharing" is quite meaningless. These unshared electron pairs are called lone pairs. Classic SEO techniques are the ones which were extensively used in the earlier days of SEO. It’s a Very helpful article for me. Ethane, $$\ce{C_2H_6}$$, has a geometry related to that of methane. Give a physical reason why this might be expected. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. In this case, however, the fluorine atoms and the lone pair could be arranged in two different ways with two different resultant molecular structures. The main difference between electron geometry and molecular geometry is that electron geometry is found by taking both lone electron pairs and bonds in a molecule whereas molecular geometry is found using only the bonds present in the molecule. Hence, Electron Domain theory accounts for the geometry of $$\ce{PCl_5}$$. We find that each fluorine atom is singly bonded to the sulfur atom, and that there is a lone pair of electrons on the sulfur. (a) A tetrahedron is formed by placing four points on a sphere as far apart from one another as possible. Here again, there are four pairs of valence shell electrons about the central atoms. As such, it is reasonable to conclude that the bond angles are determined by the mutual repulsion of these electron pairs, and are thus expected to be $$109.5^\text{o}$$, which is close but not exact. For molecules of the general formula ABn, n can be greater than four _____. What determines which geometry will be observed in a particular molecule? Focusing for the moment on methane, the four pairs of electrons must be equivalent to one another, since the four $$\ce{C-H}$$ bonds are equivalent, so we can assume that the electron pairs are all the same distance from the central carbon atom. These ideas can be extended by more closely examining the geometry of ethene, $$\ce{C_2H_4}$$. Part A). We'll look at the molecular geometry … These molecules are clearly not tetrahedral, like $$\ce{CH_4}$$, since neither contains the requisite five atoms to form the tetrahedron. We expect from our Electron Domain model that those four pairs should be arrayed in a tetrahedron, without regard to whether they are bonding or lone-pair electrons. If the carbon atom is at the center of this tetrahedron and the four electron pairs placed at the corners, then the hydrogen atoms also form a tetrahedron about the carbon. The two carbons are bonded together, and each is bonded to three hydrogens. Solution for Draw the lewis structure, determine the electron domain geometry, and predict the molecular geometry for the followings. Thus, with five electron pairs around the central atom, we expect the electrons to arrange themselves in a trigonal bipyramid, similar to the arrangement in $$\ce{PCl_5}$$ in Figure 7.3. answer choices . We conclude that our model can be extended to understanding the geometries of molecules with double (or triple) bonds by treating the multiple bond as two electron pairs confined to a single domain. The table of molecular geometries can be found in the first figure. In these cases, the molecular geometry is the same as the electron domain geometry. Lone pair electrons apparently generate a greater repulsion, thus slightly reducing the angles between the bonded pairs of electrons. Molecular geometry, on the other hand, helps us understand the entire atom and its arrangement. Molecular geometry is the name of the geometry used to describe the shape of a molecule. The last two molecules in the examples above (CH4 and NH3) are both tetrahedral. <a href=http://www.chemin10.com> chemistry tutor online </a> <a href=http://www.chemin10.com> online chemistry tutoring </a> how to download books from computer to nook. thanks very much.... i really got what i wanted thank. BrF 3 contains three bonded and two nonbonded electron domains, giving a trigonal pyramidal e-domain geometry and a T shaped molecular geometry. (c). For homework help in math, chemistry, and physics: www.tutor-homework.com. I'm looking forward for more helpful articles from you. This model also accounts, at least approximately, for the bond angles of $$\ce{H_2O}$$ and $$\ce{NH_3}$$. Tags: Question 14 . Viewed sideways, this structure looks something like a seesaw. If one ED is a lone pair, then the lone pair takes an equatorial position and the molecule has a seesaw geometry. How can we position four electron pairs at a fixed distance from the central atom but as far apart from one another as possible? This is, as illustrated in Figure 7.2b, the correct geometry of a methane molecule. Question: Give The Electron-domain And Molecular Geometries For The Following Molecules And Ions. Once we have developed an understanding of the relationship between molecular structure and chemical bonding, we can attempt an understanding of the relationship of the structure and bonding in a polyatomic molecule to the physical and chemical properties we observe for those molecules. Using a styrofoam or rubber ball, prove to yourself that a tetrahedral arrangement provides the maximum separation of four points on the surface of the ball. In molecules in crystalline form, the geometry of the molecule is revealed by irradiating the crystal with x-rays and analyzing the patterns formed as the x-rays diffract off of the crystal.). A number of atoms, including $$\ce{C}$$, $$\ce{N}$$, $$\ce{O}$$, $$\ce{P}$$, and $$\ce{S}$$, can form double or triple bonds as needed to complete an octet. The electron-domain geometry and the molecular geometry of a molecule of the general formula ABn will always be the same if _____. (The measurement of these geometric properties is difficult, involving the measurement of the frequencies at which the molecule rotates in the gas phase. Thus there must be 10 valence shell electrons around the phosphorus atom. Although this model accounts for the observed geometries, why should lone pair electrons generate a greater repulsive effect? In applying Electron Domain theory to understand this geometry, we must place three points on the surface of a sphere with maximum distance between the points. Moreover, the bond angle in water, with two lone pairs, is less than the bond angles in ammonia, with a single lone pair. Then attaching the hydrogens (two for oxygen, three for nitrogen) produces a prediction of bond angles of $$109.5^\text{o}$$, very close indeed to the observed angles of $$104.5^\text{o}$$ in $$\ce{H_2O}$$ and $$107^\text{o}$$ in $$\ce{NH_3}$$. Part A The electron-domain geometry and molecular geometry of ammonia are _____ and _____, respectively. The molecular geometry of PF 5 is trigonal bipyramidal with symmetric charge distribution. The geometry of a molecule includes a description of the arrangements of the atoms in the molecule. Furthermore, $$\ce{H_2O}$$ is a bent molecule, with the $$\ce{H-O-H}$$ angle equal to $$104.5^\text{o}$$. The geometry of $$\ce{BCl_3}$$ is also given in Figure 7.2: it is trigonal planar, with all four atoms lying in the same plane, and all $$\ce{Cl-B-Cl}$$ bond angles equal to $$120^\text{o}$$. A trigonal bipyramid forms when there are five electron domains. The term electron-pair geometry is the name of the geometry of the electron-pair/groups/domains on the central atom, whether they are bonding or non-bonding. (b) The dotted lines illustrate that the hydrogens form a tetrahedron about the carbon atom. In applying Electron Domain theory to understand this geometry, we must place three points on the surface of a sphere with maximum distance between the points. First, $$\ce{PCl_5}$$ is a stable gaseous compound in which the five chlorine atoms are each bonded to the phosphorus atom. VSEPR Notation. Oracle & SQL), Environmental Science, Ecology, & Conservation, Algebra / Trigonometry, Precalculus, Plane Geometry, College Algebra, Pre-calculus (w/o Trig), Foundations of Math, Finite Math, Mathematics - Developmental or Learning Support Math & Math for Nursing, Electrical & Biomedical Engineering (including Electronics). Experiments reveal that the geometry of $$\ce{PCl_5}$$ is that of a trigonal bipyramid: three of the chlorine atoms form an equilateral triangle with the $$\ce{P}$$ atom in the center, and the other two chlorine atoms are on top of and below the $$\ce{P}$$ atom. Q. In general, atoms of Groups IV through VII bond so as to complete an octet of valence shell electrons. We consider two such molecules illustrated in Figure 7.3. I hate Mastering Chem, so I hope this helps. Each $$\ce{H-C-H}$$ angle is $$109.5^\text{o}$$ and each $$\ce{H-C-C}$$ angle is $$109.5^\text{o}$$. This chemistry video tutorial provides a basic introduction into molecular geometry and vsepr theory. With 2 electron domains, we would predict, that carbon dioxide is a linear molecule. Explain why these statements are not inconsistent. (It is worth noting that these angles are not exactly equal to $$109.5^\text{o}$$, as in methane. Quick note: in the last sentence of your second paragraph, you state that the lone pairs are not considered when determining molecular geometry. I am sure this has relevance to many of us out there. $$\ce{HCl}$$ or $$\ce{O_2}$$. However, the arrangement of these electron pairs, and thus the bonded atoms, about each carbon is not even approximately tetrahedral. there are no lone pairs. If the electron pairs in the triple bond are treated as a single domain, then each carbon atom has only two domains each. Figure 7.2: The tetrahedral structure of methane. However, only $$\ce{CH_4}$$ is considered a tetrahedral molecule. Since there is 4 electron domains which are all single bonds without any lone pairs, the molecular geometry is tetrahedral. When you draw a Lewis structure for a molecule on paper, you are making a two-dimensional representa-tion of the atoms.In reality however, molecules are not flat—they are three-dimensional.The true shape of a molecule is important because it determines many physical and … We find that the three points form an equilateral triangle in a plane with the center of the sphere, so Electron Domain is again in accord with the observed geometry. The lone pair on the nitrogen is important and if it wasn’t there, we would have a hypothetic … Count the domains* around the S. You’ll find 4. two are bonds and two are lonepairs. Note that two of the fluorines form close to a straight line with the central sulfur atom, but the other two are approximately perpendicular to the first two and at an angle of $$101.5^\text{o}$$ to each other. To account for the observed angle, we begin with our valence shell electron pair sharing model, and we note that, in the Lewis structures of these molecules, the central atom in each bond angle of these molecules contains four pairs of valence shell electrons. Given this assumption, separating the three independent groups of electron pairs about a carbon atom produces an expectation that all three pairs should lie in the same plane as the carbon atom, separated by $$120^\text{o}$$ angles. Ammonia, $$\ce{NH_3}$$, is a pyramid-shaped molecule, with the hydrogens in an equilateral triangle, the nitrogen above the plane of the triangle, and a $$\ce{H-N-H}$$ angle equal to $$107^\text{o}$$. A polyatomic molecule contains more than two atoms. We can make a prediction of what its molecular geometry will be, here is the Lewis structure. The answer is trigonal bipyramidal, T-shaped, respectively- I do not understand the approach PLEASE EXPLAIN HOW . The $$\ce{F}$$ atoms form an octahedron about the central $$\ce{S}$$ atom: four of the $$\ce{F}$$ atoms form a square with the $$\ce{S}$$ atom at the center, and the other two $$\ce{F}$$ atoms are above and below the $$\ce{S}$$ atom. The three $$\ce{Cl}$$ atoms form an equilateral triangle. HCN Electron-domain Geometry Linear Trigonal Planar Tetrahedral Trigonal Bipyramidal Octahedral Part B). What is the molecular geometry of ClF 5? Note, however, that we do not describe the geometries of $$\ce{H_2O}$$ and $$\ce{NH_3}$$ as "tetrahedral", since the atoms of the molecules do not form tetrahedrons, even if the valence shell electron pairs do. A little reflection reveals that this question is equivalent to asking how to place four points on the surface of a sphere spread out from each other as far apart as possible. EXPERIMENT 9 MOLECULAR GEOMETRY OF SIMPLE COMPOUNDS Objectives: To determine the types of bonds and the geometrie structure for a set of molecules and jons, Equipment Molecular model kit obtained from the lab assistant The VSEPR (Valence-Shell Electron-Pair Repulsion) model is based on the electrostatic repulsion between like charges. Forcing these domains to opposite sides from one another accurately predicts $$180^\text{o}$$ $$\ce{H-C-C}$$ bond angles. Similar reasoning using Electron Domain theory as applied to triple bonds correctly predicts that acetylene, $$\ce{HCCH}$$, is a linear molecule. Applied in this form, Electron Domain theory can help us understand the linear geometry of $$\ce{CO_2}$$. The actual molecular structure in Figure 7.4 shows clearly that the lone pair goes on the equatorial position. It is for this reason that we refer to the model as Electron Domain theory. It helps understand the entire atom and its arrangement. Thank you ... Good post,This was exactly what I needed to read today! As stated above, molecular geometry and electron-group geometry are the same when there are no lone pairs. The observed geometry of $$\ce{SF_6}$$, as shown in Figure 7.2, is highly symmetric: all bond lengths are identical and all bond angles are $$90^\text{o}$$. At a simple level, the molecular structure tell us which atoms are bonded to which. We thus assume the nuclear structure of the atom, and we further assume the existence of a valence shell of electrons in each atom which dominates the chemical behavior of that atom. The valence shell electron pairs about the central atom in each of the molecules $$\ce{H_2O}$$, $$\ce{NH_3}$$, and $$\ce{CH_4}$$ are arranged approximately in a tetrahedron. A molecule can have a different shape when  referring to its, Assembly Language Programming & Microprocessors, Database Programming (incl. I admire all the helpful data you've shared in your articles. In current form, the Electron Domain model does not account for the observed geometry of $$\ce{C_2H_4}$$, in which each $$\ce{H-C-H}$$ bond angle is $$116.6^\text{o}$$ and each $$\ce{H-C-C}$$ bond angle is $$121.7^\text{o}$$ and all six atoms lie in the same plane. We know that double bonds are generally stronger and have shorter lengths than single bonds, and triple bonds are stronger and shorter than double bonds. The result of this greater repulsion is a slight "pinching" of the $$\ce{H-C-H}$$ bond angle to less than $$120^\text{o}$$. K. FosterLaboratory TechnicianAcademic Support CenterSouthwest TN Community CollegeI tutor courses in Math, Physics, and Chemistry. Based on VSEPR Theory (Valence Shell Electron Pair Repulsion Theory) the electron clouds on atoms and lone pair of electrons around the Cl will repel each other. As a common example, $$\ce{CO_2}$$ is a linear molecule. Thanks for sharing information that is actually helpful. What geometries are actually observed? However, each molecule does contain a central atom surrounded by four pairs of valence shell electrons. However, with a triatomic molecule (three atoms), there are two possible geometries: the atoms may lie on a line, producing a linear molecule, or not, producing a bent molecule. Assess the accuracy of the following reasoning and conclusions: Once finding out, you will see that the AX2N2 has a ‘Bent Molecular Geometry.’ H2O, which is a three atom molecule, comes with the angular shape.. H2O Bond Angles. Great blog, enjoyed browsing through the site, Excellent! We conclude that molecular geometry is determined by minimizing the mutual repulsion of the valence shell electron pairs. Thus more free to move about the central atom, these lone pair electrons must have a more significant repulsive effect on the other pairs of electrons.