To start with making the Lewis Structure of HCN, we will first determine the central atom. water molecules. hydrogen bonding, you should be able to remember And so once again, you could the number of carbons, you're going to increase the think about the electrons that are in these bonds hydrogen bonding is present as opposed to just Why can't a ClH molecule form hydrogen bonds? Wow! Ionic compounds - Forces between the positive and negative - Ionic forces are present in ionic compounds Covalent compounds Have no charges but can have what type of forces (2) and bonds (1)? dimethyl sulfoxide (boiling point = 189.9C) > ethyl methyl sulfide (boiling point = 67C) > 2-methylbutane (boiling point = 27.8C) > carbon tetrafluoride (boiling point = 128C). I am glad that you enjoyed the article. electronegative than hydrogen. The first compound, 2-methylpropane, contains only CH bonds, which are not very polar because C and H have similar electronegativities. A C60 molecule is nonpolar, but its molar mass is 720 g/mol, much greater than that of Ar or N2O. The same situation exists in And so like the And so even though And so the three So these are the weakest The picture above shows a pair of HCOOH molecules (a dimer) joined by a pair of hydrogen bonds. In water at room temperature, the molecules have a certain, thoughts do not have mass. Hydrogen bonding is also a dipole-dipole interaction, but it is such a strong form of dipole-dipole bonding that it gets its own name to distinguish it from the others. and we have a partial positive. Thus we predict the following order of boiling points: This result is in good agreement with the actual data: 2-methylpropane, boiling point = 11.7C, and the dipole moment () = 0.13 D; methyl ethyl ether, boiling point = 7.4C and = 1.17 D; acetone, boiling point = 56.1C and = 2.88 D. Arrange carbon tetrafluoride (CF4), ethyl methyl sulfide (CH3SC2H5), dimethyl sulfoxide [(CH3)2S=O], and 2-methylbutane [isopentane, (CH3)2CHCH2CH3] in order of decreasing boiling points. Since HCN is a polar molecular without hydrogen bonding present, the main intermolecular force is Dipole-Dipole (also present is London Dispersion Forces). While intermolecular forces take place between the molecules, intramolecular forces are forces within a molecule. you look at the video for the tetrahedral those electrons closer to it, therefore giving oxygen a So we have a polarized The intermolecular forces are entirely different from chemical bonds. Direct link to Marwa Al-Karawi's post London Dispersion forces . Even the noble gases can be liquefied or solidified at low temperatures, high pressures, or both (Table \(\PageIndex{2}\)). 1 / 37. The sharp change in intermolecular force constant while passing from . Identify the most significant intermolecular force in each substance. Ionic compounds have what type of forces? Since the ammonia ion has hydrogen atoms bonded to nitrogen, a very electronegative atom, the molecule is also polar since the nitrogen atom more strongly pulls on the electrons from the hydrogen atoms than the hydrogens themselves do. (a) CH4, (b) PF3, (c) CO2, (d) HCN, (e) HCOOH (methanoic acid). 2. Term. On average, the two electrons in each He atom are uniformly distributed around the nucleus. Titan, Saturn's largest moon, has clouds, rain, rivers and lakes of liquid methane. But it is there. Hence, Hydrogen Cyanide, HCN, has ten valence electrons. The four compounds are alkanes and nonpolar, so London dispersion forces are the only important intermolecular forces. This liquid is used in electroplating, mining, and as a precursor for several compounds. What is the predominant intermolecular force in HCN? Hydrogen bonding is the dominant intermolecular force in water (H2O). Draw the hydrogen-bonded structures. And it has to do with These forces mediate the interactions between individual molecules of a substance. And to further understand Hydrogen Cyanides physical properties, it is vital to know its Lewis structure and molecular geometry. e) Vapor Pressure As the intermolecular forces increase (), the vapor pressure decreases (). 2. Because, HCN is a linear molecu View the full answer Transcribed image text: What types of intermolecular forces are present for molecules of HCN? For hydrogen bonding to occur the molecule must contain N, O, or F, bonded to a hydrogen atom. the covalent bond. - Larger size means more electrons are available to form dipoles, List in order of least strongest to stongest And so there's going to be Because the electrons are in constant motion, however, their distribution in one atom is likely to be asymmetrical at any given instant, resulting in an instantaneous dipole moment. Viscosity Argon and N2O have very similar molar masses (40 and 44 g/mol, respectively), but N2O is polar while Ar is not. Molecules can have any mix of these three kinds of intermolecular forces, but all substances at . Acetone contains a polar C=O double bond oriented at about 120 to two methyl groups with nonpolar CH bonds. These attractive interactions are weak and fall off rapidly with increasing distance. Direct link to SuperCipher's post A double bond is a chemic, Posted 7 years ago. 12.6: Intermolecular Forces: Dispersion, DipoleDipole, Hydrogen Bonding, and Ion-Dipole is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. H Bonds, 1. Ans. A polar compound dissolves another POLAR COMPOUND better than a nonpolar, Benzene (C6H6) dissolves better in H20 or CCl4, Dipole - Dipole primarily hydrogens for methane. And what some students forget A. this intermolecular force. Since HCN is a polar molecular. different poles, a negative and a positive pole here. coming off of the carbon, and they're equivalent In this video we'll identify the intermolecular forces for HCN (Hydrogen cyanide). can you please clarify if you can. intermolecular forces, and they have to do with the The hydrogen bond is the strongest intermolecular force. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. we have a carbon surrounded by four Interactions between these temporary dipoles cause atoms to be attracted to one another. In N 2, you have only dispersion forces. This molecule has an H atom bonded to an O atom, so it will experience hydrogen bonding. Therefore dispersion forces and dipole-dipole forces act between pairs of HCN molecules. For each of the molecules below, list the types of intermolecular force which act between pairs of these molecules. (Despite this seemingly low value, the intermolecular forces in liquid water are among the strongest such forces known!) first intermolecular force. ex. Due to the fact that the polar bonds do not cancel in the remaining molecules, they exhibit dipole - dipole interactions: these are stronger than London dispersion forces. The answer lies in the highly polar nature of the bonds between hydrogen and very electronegative elements such as O, N, and F. The large difference in electronegativity results in a large partial positive charge on hydrogen and a correspondingly large partial negative charge on the O, N, or F atom. dispersion forces. Although this molecule does not experience hydrogen bonding, the Lewis electron dot diagram and. Despite quite a small difference in Carbon and Nitrogens electronegativities, it is considered a slightly polar bond as Nitrogen will try to pull the electrons to itself. (a) If the acceleration of the cart is a=20ft/s2a=20 \mathrm{ft} / \mathrm{s}^2a=20ft/s2, what normal force is exerted on the bar by the cart at BBB ? The hydrogen is losing a Intermolecular Forces: The forces of attraction/repulsion between molecules. around the world. Click the card to flip . 2. The strengths of London dispersion forces also depend significantly on molecular shape because shape determines how much of one molecule can interact with its neighboring molecules at any given time. Intermolecular forces play a crucial role in this phase transformation. And because each In 1930, London proposed that temporary fluctuations in the electron distributions within atoms and nonpolar molecules could result in the formation of short-lived instantaneous dipole moments, which produce attractive forces called London dispersion forces between otherwise nonpolar substances. London dispersion forces and dipole-dipole forces are collectively known as van der Waals forces. Now that we have completed the valence shell for Hydrogen let us do the same for the Carbon atom. Substances with high intermolecular forces have high melting and boiling points. Asked for: order of increasing boiling points. And this just is due to the And due to the difference in electronegativities between Carbon and Hydrogen, the vector represents charge will be drawn from Hydrogen to Carbon. Direct link to Susan Moran's post Hi Sal, Intermolecular forces Forces between molecules or ions. It does contain F, but it does not contain any hydrogen atoms so there is no possibility of forming hydrogen bonds. As a result, the strongest type of intermolecular interaction between molecules of these substances is the London dispersion force . And so the boiling I am a 60 year ol, Posted 7 years ago. In contrast, each oxygen atom is bonded to two H atoms at the shorter distance and two at the longer distance, corresponding to two OH covalent bonds and two OH hydrogen bonds from adjacent water molecules, respectively. 2. I learned so much from you. And that's where the term Intramolecular Forces: The forces of attraction/repulsion within a molecule. As this molecule has a linear molecular geometry, HCN has bond angles of 180 degrees. 2. a molecule would be something like Video Discussing Dipole Intermolecular Forces. Direct link to Ernest Zinck's post You can have all kinds of, Posted 7 years ago. The predicted order is thus as follows, with actual boiling points in parentheses: He (269C) < Ar (185.7C) < N2O (88.5C) < C60 (>280C) < NaCl (1465C). Because hydrogen bonds are considered as a type of dipole-dipole force, some books will just list dispersion forces and hydrogen bonds as relevant to methanoic acid. And even though the The strongest intermolecular forces in each case are: "CHF"_3: dipole - dipole interaction "OF"_2: London dispersion forces "HF": hydrogen bonding "CF"_4: London dispersion forces Each of these molecules is made up of polar covalent bonds; however in order for the molecule itself to be polar, the polarities must not cancel one another out. Of the compounds that can act as hydrogen bond donors, identify those that also contain lone pairs of electrons, which allow them to be hydrogen bond acceptors. to form an extra bond. Start typing to see posts you are looking for. What kind of attractive forces can exist between nonpolar molecules or atoms? Now, if you increase As a result, the boiling point of neopentane (9.5C) is more than 25C lower than the boiling point of n-pentane (36.1C). Arrange n-butane, propane, 2-methylpropane [isobutene, (CH3)2CHCH3], and n-pentane in order of increasing boiling points. And so we say that this All right. Direct link to Harrison Sona Ndalama's post Why can't a ClH molecule , Posted 7 years ago. As a result, one atom will pull the shared electron pairs towards itself, making it partially negative and the other atom partially positive. Types of intramolecular forces of attraction Ionic bond: This bond is formed by the complete transfer of valence electron (s) between atoms. Consequently, even though their molecular masses are similar to that of water, their boiling points are significantly lower than the boiling point of water, which forms four hydrogen bonds at a time. They occur in nonpolar molecules held together by weak electrostatic forces arising from the motion of electrons. Hence Hydrogen Cyanide has linear molecular geometry. them into a gas. Weaker dispersion forces with branching (surface area increased), non polar (d) HCN is a linear molecule; it does have a permanent dipole moment; it does contain N, however the nitrogen is not directly bonded to a hydrogen. For example, it requires 927 kJ to overcome the intramolecular forces and break both OH bonds in 1 mol of water, but it takes only about 41 kJ to overcome the intermolecular attractions and convert 1 mol of liquid water to water vapor at 100C. has a dipole moment. Consider a pair of adjacent He atoms, for example. Hydrogen has one valence electron, and it only needs one more electron to complete its valence shell as it is an exception to the octet rule. And this one is called d) KE and IF comparable, and very small. Yes. Direct link to Jack Friedrich's post At 7:40, he says that the, Posted 7 years ago. Direct link to awemond's post Suppose you're in a big r, Posted 5 years ago. molecule is polar and has a separation of Any molecule that has a difference of electronegativities of any dipole moment is considered as polar. In general, however, dipoledipole interactions in small polar molecules are significantly stronger than London dispersion forces, so the former predominate. And here is why: Carbon has an electronegativity of 2.5, Hydrogens electronegativity is 2.1, and Nitrogen has an electronegativity of 3. You'll get a detailed solution from a subject matter expert that helps you learn core concepts. so a thought does not have mass. molecules together would be London And so let's look at the In the video on for hydrogen bonding are fluorine, Dipole-dipole will be the main one, and also will have dispersion forces. So this is a polar dipole-dipole interaction. bond angle proof, you can see that in Direct link to Venkata Sai Ram's post how can a molecule having, Posted 9 years ago. 11. number of attractive forces that are possible. Similarly, as Nitrogen is more electronegative than Carbon, the vector will be towards Nitrogen from Carbon. Intermolecular forces are electrostatic in nature; that is, they arise from the interaction between positively and negatively charged species. Direct link to smasch2109's post If you have a large hydro, Posted 9 years ago. Keep reading! Intermolecular So the methane molecule becomes Although CH bonds are polar, they are only minimally polar. In fact, the ice forms a protective surface layer that insulates the rest of the water, allowing fish and other organisms to survive in the lower levels of a frozen lake or sea. H20, NH3, HF Dipole-dipole forces require that the molecules have a permanent dipole moment, so determine the shape of each molecule (draw a Lewis structure, then use VSEPR theory) and see if the shape allows a permanent dipole moment. Which of the following is not a design flaw of this experiment? Hydrogen Cyanide is a colorless, flammable, and poisonous chemical liquid. Now, you need to know about 3 major types of intermolecular forces. is that this hydrogen actually has to be bonded to another Isobutane C4H10. so it might turn out to be those electrons have a net Gabriel Forbes is right, The Cl atom is a lot larger than N, O, or F. Does london dispersion force only occur in certain elements? molecule as well. Cg = kPg. Intermolecular forces, often abbreviated to IMF, are the attractive and repulsive forces that arise between the molecules of a substance. 3. partial negative over here. Therefore only dispersion forces act between pairs of CO2 molecules. I've drawn the structure here, but if you go back and Thus, London dispersion forces are responsible for the general trend toward higher boiling points with increased molecular mass and greater surface area in a homologous series of compounds, such as the alkanes (part (a) in Figure \(\PageIndex{4}\)). - Electrons are in motion around the nucleus so an even distribution is not true all the time. and we have a partial positive, and then we have another Volatile substances have low intermolecular force. A) 10.71 B) 6.27 C) 4709 D) 12.28 E) 8.83 A) About Priyanka To read, write and know something new every day is the only way I see my day! Every molecule experiences london dispersion as an intermolecular force. Although Hydrogen is the least electronegative, it can never take a central position. The molecules are said to be nonpolar. Represented by the chemical formula, HCN is one of those molecules that has an interesting Lewis structure. difference in electronegativity for there to be a little Dispersion Dispersion factors are stronger and weaker when? electrons in this double bond between the carbon Whereas Carbon has four valence electrons and Nitrogen has five valence electrons. The solvent then is a liquid phase molecular material that makes up most of the solution. 3. about these electrons here, which are between the partially charged oxygen, and the partially positive 5. The dispersion force is present in all atoms and molecules, whether they are polar or not. H-bonds, Non polar molecules Because organic chemistry can perform reactions in non-aqueous solutions using organic solvents. So at room temperature and And so since room temperature The University of New South Wales ABN 57 195 873 179. The substance with the weakest forces will have the lowest boiling point. the carbon and the hydrogen. The figure above shown CH4 in two views: one shows it as it is commonly drawn, with one H at the top and three H's at the bottom. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. intermolecular force. an intramolecular force, which is the force within a molecule. It should therefore have a very small (but nonzero) dipole moment and a very low boiling point. Doubling the distance (r 2r) decreases the attractive energy by one-half. The distribution of charges in molecules results in a dipole, which leads to strong intermolecular forces. And so in this case, we have methane molecule here, if we look at it, And that small difference And once again, if I think Question options: dispersion, dipole, ion-dipole, hydrogen bonding I know that oxygen is more electronegative In larger atoms such as Xe, however, the outer electrons are much less strongly attracted to the nucleus because of filled intervening shells. And since oxygen is how can a molecule having a permanent dipole moment induce some temporary dipole moment in a neighbouring molecule. Why do strong intermolecular forces produce such anomalously high boiling points and other unusual properties, such as high enthalpies of vaporization and high melting points? electronegative atoms that can participate in Direct link to Ernest Zinck's post Hydrogen bonding is also , Posted 5 years ago. We're talking about an C. The same type of strawberries were grown in each section. in this case it's an even stronger version of Here's your hydrogen showing However, #"HF"# exhibits hydrogen bonding - a stronger force still that is similar to the dipole - dipole interaction - whilst #"CHF"_3# does not. The slender 2 -slug bar ABA BAB is 3ft3 \mathrm{ft}3ft long. polarized molecule. a quick summary of some of the If you have a large hydrocarbon molecule, would it be possible to have all three intermolecular forces acting between the molecules? Neopentane is almost spherical, with a small surface area for intermolecular interactions, whereas n-pentane has an extended conformation that enables it to come into close contact with other n-pentane molecules. On the other hand, atoms that do not have any electronegativity difference equally share the electron pairs. The type of intermolecular forces (IMFs) exhibited by compounds can be used to predict whether two different compounds can be mixed to form a homogeneous solution (soluble or miscible). Legal. dipole-dipole interaction, and therefore, it takes The strength of intermolecular force from strongest to weakest follows this order: Hydrogen bonding > Dipole-dipole forces > London dispersion forces. little bit of electron density, therefore becoming The only intermolecular It is covered under AX2 molecular geometry and has a linear shape. A molecule is said to be polar if there is a significant electronegativity difference between the bonding atoms. The CO bond dipole therefore corresponds to the molecular dipole, which should result in both a rather large dipole moment and a high boiling point. Thanks. When electrons move around a neutral molecule, they cluster at one end resulting in a dispersion of charges. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Kinds of Intermolecular Forces. Set your categories menu in Theme Settings -> Header -> Menu -> Mobile menu (categories). bit extra attraction. Make sure to label the partial charges and interactions x Clear sketch Submit response T Switch to text response This problem has been solved! Suppose you're in a big room full of people wandering around. And an intermolecular therefore need energy if you were to try And so you would was thought that it was possible for hydrogen Intermolecular forces, also known as intermolecular interactions, are the electrostatic forces of attraction between molecules in a compound. situation that you need to have when you 1. Direct link to Ernest Zinck's post In water at room temperat, Posted 7 years ago. It occurs when a polar molecule consisting of partially positive hydrogen (H) atom is attracted to a partially negative atom of another molecule. A strawberry grower divides a large field into three sections: the first bordering a grove of trees, the second in the middle, and the third bordering an interstate. And, of course, it is. No hydrogen bonding, however as the H is not bonded to the N in. When you are looking at a large molecule like acetic anhydride, you look at your list of intermolecular forces, arranged in order of decreasing strength. Water has a stronger intermolecular force than isopropyl alcohol since it takes longer to evaporate. A) dipole-dipole attraction - B) ion-dipole attraction C) ionic bonding D) hydrogen bonding E) London dispersion forces. Predict which compound in the following pair has the higher boiling point: - Forces between the positive and negative. those extra forces, it can actually turn out to be The most significant intermolecular force for this substance would be dispersion forces. The three compounds have essentially the same molar mass (5860 g/mol), so we must look at differences in polarity to predict the strength of the intermolecular dipoledipole interactions and thus the boiling points of the compounds. As a result, it is relatively easy to temporarily deform the electron distribution to generate an instantaneous or induced dipole. and the oxygen. The way to recognize when Polar covalent bonds behave as if the bonded atoms have localized fractional charges that are equal but opposite (i.e., the two bonded atoms generate a dipole). If you're seeing this message, it means we're having trouble loading external resources on our website. And so, of course, water is P,N, S, AL, Ionization energy increasing order (c) CO2 is a linear molecule; it does not have a permanent dipole moment; it does contain O, however the oxygen is not bonded to a hydrogen. Polar molecules have what type of intermolecular forces? It has two poles. There are two additional types of electrostatic interaction that you are already familiar with: the ionion interactions that are responsible for ionic bonding, and the iondipole interactions that occur when ionic substances dissolve in a polar substance such as water. Source: Dipole Intermolecular Force, YouTube(opens in new window) [youtu.be]. forces are the forces that are between molecules. In contrast, the energy of the interaction of two dipoles is proportional to 1/r3, so doubling the distance between the dipoles decreases the strength of the interaction by 23, or 8-fold. 56 degrees Celsius. If ice were denser than the liquid, the ice formed at the surface in cold weather would sink as fast as it formed. The overall order is thus as follows, with actual boiling points in parentheses: propane (42.1C) < 2-methylpropane (11.7C) < n-butane (0.5C) < n-pentane (36.1C). And let's analyze Therefore dispersion forces, dipole-dipole forces and hydrogen bonds act between pairs of HCOOH molecules. Note that various units may be used to express the quantities involved in these sorts of computations. The LibreTexts libraries arePowered by NICE CXone Expertand 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. dipole-dipole interaction that we call hydrogen bonding. Usually you consider only the strongest force, because it swamps all the others. We also have a To summarize everything in this article, we can say that: To read, write and know something new every day is the only way I see my day! The rest two electrons are nonbonding electrons. more energy or more heat to pull these water 4. Like Hydrogen will have one electron, Carbon will have four electrons, and Nitrogen will have five electrons around its atom like this: If you look at the structure closely, you will realize that Hydrogen can share one electron with the Carbon atom and become stable. And so there could be fact that hydrogen bonding is a stronger version of nonpolar as a result of that. Let's look at another Helium is nonpolar and by far the lightest, so it should have the lowest boiling point. This effect is similar to that of water, where . Source: Dispersion Intermolecular Force, YouTube(opens in new window) [youtu.be]. HCN has a total of 10 valence electrons. molecules of acetone here and I focus in on the And then place the remaining atoms in the structure. Or is it just hydrogen bonding because it is the strongest? force, in turn, depends on the CO2, CH4, Noble gases (have dispersion forces between atoms when come together, don't make compounds), Hydrogen bonds are between molecules of H and, Between H and N,O, or F intermolecular forces. and we get a partial positive. those electrons closer to it, giving the oxygen a partial And it's hard to tell in how intermolecular force. The ease of deformation of the electron distribution in an atom or molecule is called its polarizability. Direct link to tyersome's post Good question! It is covered under AX2 molecular geometry and has a linear shape. Molecules in liquids are held to other molecules by intermolecular interactions, which are weaker than the intramolecular interactions that hold the atoms together within molecules and polyatomic ions. dipole-dipole interaction. This effect, illustrated for two H2 molecules in part (b) in Figure \(\PageIndex{3}\), tends to become more pronounced as atomic and molecular masses increase (Table \(\PageIndex{2}\)). Doubling the distance therefore decreases the attractive energy by 26, or 64-fold. Because molecules in a liquid move freely and continuously, molecules always experience both attractive and repulsive dipoledipole interactions simultaneously, as shown in Figure \(\PageIndex{2}\). document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This molecule is made up of three different atoms: Hydrogen, The molecular Geometry of any given molecule helps understand its three-dimensional structure and the arrangement of atoms in a molecule, and its shape. How do you calculate the dipole moment of a molecule? these two molecules together. Now we can use k to find the solubility at the lower pressure. On average, however, the attractive interactions dominate. Identify the compounds with a hydrogen atom attached to O, N, or F. These are likely to be able to act as hydrogen bond donors. C, Be, Ca, Sr, B, Kr, Properties of Solids, Liquids, and Gases, Sol. 1. start to share electrons. London Dispersion Forces. positive and a negative charge. Well, that rhymed. What kind of intermolecular forces act between a hydrogen cyanide (HCN) molecule and an oxide (02-) anion? of valence electrons in Hydrogen + No. KBr (1435C) > 2,4-dimethylheptane (132.9C) > CS2 (46.6C) > Cl2 (34.6C) > Ne (246C). - Interaction is weak and short-lived, The strength of London dispersion depends on, - Strength of attractions depend on the molar mass of the substance. And therefore, acetone Place the Hydrogen and Nitrogen atoms on both terminal sides of the Carbon like this: Once you have arranged the atoms, start placing the valence electrons around individual atoms. And it is, except to pull them apart. Electrostatic interactions are strongest for an ionic compound, so we expect NaCl to have the highest boiling point. Direct link to Sastha Rajamanikandan's post At 1:27, he says "double , Posted 5 years ago. The strongest intermolecular forces in each case are: Each of these molecules is made up of polar covalent bonds; however in order for the molecule itself to be polar, the polarities must not cancel one another out. And so that's different from Dipoledipole interactions arise from the electrostatic interactions of the positive and negative ends of molecules with permanent dipole moments; their strength is proportional to the magnitude of the dipole moment and to 1/r3, where r is the distance between dipoles. (b) PF3 is a trigonal pyramidal molecule (like ammonia, the P has a single lone pair of electrons); it does have a permanent dipole moment. In contrast, the hydrides of the lightest members of groups 1517 have boiling points that are more than 100C greater than predicted on the basis of their molar masses. Hey Horatio, glad to know that. Which combination of kinetic energy (KE) and intermolecular forces (IF) results in formation of a solid? And as per VSEPR theory, molecules covered under AX2 have a linear molecular geometry. London dispersion and hydrogen bonds.