In general, hydrogen sulfide is very toxic to obligate oxygen breathers. Water molecules can actually align themselves in the presence of an electrostatic force. Photo: doctor-a via Pixabay, CC0. Even if each B-F bond is polar, the net dipole moment iszerobecause adding the bond vectors cancels everything out.Check the full article Is BF3 polar or nonpolar?. I hope, I cleared your all doubts regarding the polarity of SO2 and also made you understand the fundamentals of the polar and non-polar bonds. As in the case of SO3, the dipole moment of each S-O bond cancels out. The molecular structure of any molecule is an important factor to determine the polarity of that molecule. Therefore, the dipole moment gets canceled out and results in a net-zero dipole moment. The electrons in hydrogen are more attracted to the electrons in oxygen because oxygen is more electronegative. Strictly speaking, H-S bonds are notcompletely non-polar. This table is just a general guide, however, with many exceptions. AsF5) to give the non-rigid -complex C6(CH3)6SO2+. Hydrogen sulfide in the body often acts a signaling molecule that regulates the amount of ATP production during cellular respiration. A polar covalent bond is a type of covalent link that is intermediate between pure covalent bonds and ionic bonds. Electrons in a polar covalent bond are shifted toward the more electronegative atom; thus, the more electronegative atom is the one with the partial negative charge. Required fields are marked *. H2SO4 works as an oxidizing and dehydrating agent. Hydrogen has an EN of 2.1 and oxygen has an EN value of 3.5. the difference between these two values is 1.4, so H-O bonds are considered polar, with a partial negative charge on the oxygen. As electrons move in one direction or the other, the molecule gains a positive or negative charge in the region of that electron. Any charges are distributed evenly across the molecule. In the case of ethane though, there is little to no difference in the amounts of electronegativity that exists between the carbon atoms and the hydrogen atoms, and little difference in the electronegativity that is found between the two carbon atoms. For instance, a molecule of water is polar in virtue of its H-O bonds. Set your categories menu in Theme Settings -> Header -> Menu -> Mobile menu (categories). The electronegativity of Sulfur is 2.58 whereas the electronegativity of Oxygen is 3.44. The side of the molecule containing both oxygen atoms is somewhat negatively charged. Disulfur monoxide or sulfur suboxide is an inorganic compound with formula S 2 O, one of the lower sulfur oxides.It is a colourless gas and condenses to give a roughly dark red coloured solid that is unstable at room temperature. Polar substances will dissolve more easily when combined with other polar molecules, and nonpolar substances dissolve more easily when combined with other nonpolar substances. However sulfur is less electronegative than oxygen. The Oxygen gas molecule O2 is an example of a nonpolar molecule. Temperature Has A Significant Influence On The Production Of SMP-Based Dissolved Organic Nitrogen (DON) During Biological Processes. Your email address will not be published. The number of, The electron geometry ofSO2is formed in the shape of a. Chemistry has a concept that is often summed up as like dissolves like. Sulfur dioxide is naturally released by volcanic activity, and it is also present in the atmosphere due to the combustion of fossil fuels. Pauling also contributed to many other fields besides chemistry. Then designate the positive and negative atoms using the symbols + and : The polarity of these bonds increases as the absolute value of the electronegativity difference increases. First draw the lewis structure: Electron geometry: trigonal bipyramidal. And if the electronegativity difference is lesser than 0.5, the bond is non-polar covalent. Figure 6.1.2: As the electronegativity difference increases between two atoms, the bond becomes more ionic. Save my name, email, and website in this browser for the next time I comment. Cesium is the least electronegative element with an electronegativity of 0.7. Sulfur monoxide is an inorganic compound with formula S O. they have a non-polar bond, or the polar bonds are symmetric, in the cases of carbon dioxide or carbon tetrachloride. Either way, there will be one part of the bond that has a slightly more positive charge and one part of the bond that has a slightly negative charge. SO3 is nonpolar and this is because of the trigonal planar shape of sulfur trioxide. A trigonal planar molecule (BF 3) may be nonpolar if all three peripheral atoms are the same, but a trigonal pyramidal molecule (NH 3) is polar because of the pair of electrons in the nitrogen atoms. If you have any questions let me know in the comment section and Ill get back to you as soon as possible. It is solid at just below room temperature and has a relatively narrow liquid range. Sulfidogenic bacteria use sulfur instead of oxygen for their metabolisms. It is because of the electronegativity difference. It's essential for predicting molecular geometry, molecule polarity, and reactivity in a compound. And also, it is important to keep in mind that two different atoms do not equally share the electron of each other. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Thus the molecule maintains its balance as a nonpolar molecule. Acetyl Group| 9 Key Points-Easy Explanation, CO2 Polar or Nonpolar| Simple Explanation , How Many Cups in a Gallon?| Cups to Pints, Quarts, and More, SO2 Lewis structure would comprise two atoms of oxygen (O) and one sulfur atom. Electronegativity is a measure of the tendency of an atom to attract electrons (or electron density) towards itself. H2S is a slightly polar molecule because of the small difference in electronegativity values of Hydrogen (2.2) and Sulfur (2.58) atoms. Metals tend to be less electronegative elements, and the group 1 metals have the lowest electronegativities. When you measure the amount of polarity of a molecule, the result is called the dipole moment. Having calculated the difference in electronic potential, we know that the Oxygen-Sulfur bond is polar. 4 electrons of sulfur bond with the two pairs of electrons from both oxygen atoms around sulfur. CO (Carbon monoxide) is polar in nature because of the difference in electronegativity of carbon (2.55) and oxygen (3.44) atoms. Because sulfur and oxygen are both non-metals, the formation of sulfur dioxide is a covalent bonding process. Sulfur dioxide SO 2, ammonia NH 3, carbon monoxide CO, ethanol C 2 H 5 OH, methanol CH 3 OH, hydrogen sulfide H 2 S, chloromethane CH 3 Cl, ozone O3, phosphorus trichloride (because it has trigonal pyramidal geometry) PCl 3 Nonpolar Molecules In a nonpolar molecule, there are no positive or negative poles formed in the molecule. The three pairs of bonding electrons are arranged in the plane at an angle of 120 degrees. This table is just a general guide, however, with many exceptions. The gas sulfur dioxide (SO2) has a polar character. If the atoms involved in a molecule share equal charge distribution, its net dipole moment is zero whereas the molecule which has a net dipole moment has unequal charge distribution as they are polar in nature. However, when there are two atoms of the same type that make up a bond, the electrons within the bond will shift position because the amount of pull that each atom has is equivalent and the electrons that each atom possesses will stay where they are. Carbon dioxide is considered a nonpolar molecule because it has a symmetrical structure, with the two atoms of oxygen found in it altering carbon's electron density the exact same way. Save my name, email, and website in this browser for the next time I comment. The human body can tolerate low concentrations of hydrogen sulfide for some time. In those nonpolar cases, the electrons shared by both atoms in a covalent bond shifts towards the atom with a greater value of electronegativity. Temperature Has A Significant Influence On The Production Of SMP-Based Dissolved Organic Nitrogen (DON) During Biological Processes. The rainwater mixed with Sulfur trioxide (SO3) is acid rain which is harmful to aquatic life as well as for humans. More of the electrons are attracted to the oxygen atoms, resulting in a net charge. In unit two, we compared atoms to puppies and electrons to bones in our analogy of how bonding works. There are five lone pairs of electrons in the molecule of SO2. Sulfur is a necessary trace element for living organisms, so the sulfur cycle is what keeps a constant supply of elemental sulfur for living organisms to use. Factors affecting the polarity of a chemical compound. When it is large, the bond is polar covalent or ionic. When concentrated or condensed, it converts to S 2 O 2 ( disulfur dioxide ). Im a mother of two crazy kids and a science lover with a passion for sharing the wonders of our universe. its level of toxicity is comparable to that of carbon monoxide (CO). If a molecule is non-polar, then the molecules either share the electrons evenly, e.g. As a result, we found a trigonal planer molecule of SO3 (Sulfur trioxide). In each bond, nitrogen is more electronegative than hydrogen. There are different degrees of polarity, and acetone is less polar than water, because only part of the acetone molecule has a polar bond. Containers may burst violently if exposed to fire or heat for a lengthy period of time. The calculated dipole moment of SO2 (sulfur dioxide) is 1.6 debyes. Some other molecules are shown in the figure below. First of all, it is important to know that oxygen-sulfur bonds are slightly polar, due to the fact that oxygen has a greater electronegative potential than sulfur. Don't see the answer that you're looking for? Many of us have a doubt regarding the polarity of SO2 (sulfur dioxide). When the difference is very small or zero, the bond is covalent and nonpolar. Bond polarities play an important role in determining the structure of proteins. The OSS angle is 112.7. SBr2 is very slightly polar because of its bent geometrical shape that retains some net dipole moment although the bond (S-Br) is nonpolar because of the very low electronegativity difference between the sulfur and bromine atoms, at last, the polarity in the SBr2 molecule is so low, it can also be considered as nonpolar in nature. My aim is to uncover unknown scientific facts and sharing my findings with everyone who has an interest in Science. The best way to view properties & trends of the elements, including electronegativity, is with our new super-cool interactive periodic table. Since hydrogen sulfide is naturally produced in the human body, the body does have mechanisms for removing hydrogen sulfide, though these mechanisms can be outpaced by a large enough dose. In addition, the presence of two lone pairs that are on the opposite side of the two Hydrogen atoms also makes the molecule more polar and causes a bent shape . Like water (H20), hydrogen sulfide is a hydrogen chalcogenidea compound made from hydrogen and a group 16 element (oxygen, sulfur, selenium, tellurium. It has two polar bonds that are symmetrically arranged. Apart from the dipole moment, the geometrical shape of the molecule also helps in determining the polarity of the molecule. Thus, hydrogen sulfide is one of the main constituents of the sulfur cycle. As a result of this, SO2 is polar. A polar bond is a type of covalent bond. In such cases as SO2, where more than one lone pair group is present, the geometrical shape of the molecule is slightly different as compared to the molecule where all groups are bonds. He developed many of the theories and concepts that are foundational to our current understanding of chemistry, including electronegativity and resonance structures. Structure and bonding [ edit] [23] Disulfur dioxide is a planar molecule with C2v symmetry. Being a nonpolar molecule, the molecule shares equal charge distribution. Because of the carbonyl group, acetone is a somewhat polar molecule. SO3 is a strong oxidizing agent because Sulfur has a +6 oxidation state which is the highest as compared to other atoms in the molecule. ISSN: 2639-1538 (online). Although it has an asymmetrical molecular geometry, the entire molecule is non-polar dues to the absence of any polar bonds. Strictly speaking, H-S bonds are not completely non-polar. The structure of carbon dioxide. T. 54, 2, 2020", "Isolation and Characterization of a Non-Rigid Hexamethylbenzene-SO, https://en.wikipedia.org/w/index.php?title=Sulfur_monoxide&oldid=1142886097, a terminal ligand, with a bent MOS arrangement, for example with, a terminal ligand, with a bent MSO arrangement, analogous to bent, This page was last edited on 4 March 2023, at 21:37. Is the compound sulfur trioxide polar or non polar? Furthermore, it's diprotic in nature which holds the capacity of releasing two . It is available in three forms: gaseous monomer, crystalline trimer, and solid polymer. I must confess I am jealous of the term atom; for though it is very easy to talk of atoms, it is very difficult to form a clear idea of their nature. Michael Faraday. One of the primary natural sources of hydrogen sulfide is the activity of sulfidogenic bacteria. And one question that arises here is why Sulphur is in the center? Most alkaline elements have a similar structure to C2H6, and for this reason, it is typically said that alkaline elements are nonpolar. ??? Polar molecules tend to stick together and line up in groups, which affects the properties of polar compounds like water. SCl 4 l. nitrogen trifluoride sulfur tetrachloride NF 3 m. P 2 O 3 n. carbon disulfide diphosphorus trioxide CS 2 o. Covalent bond between the elements can be either polar or non-polar. The compound SF3N has been synthesized. For this reason, its spectroscopic signature is very well understood. A dipole moment occurs when one end of the bond is positive, and the other end is negative. Be Careful When Speaking About Lead Pollution: The Good, The Bad, And The Ugly! Does The Arrow Of Time Apply To Quantum Systems? S 2 O occurs rarely in natural atmospheres, but can be made by a variety of laboratory procedures. Hydrogen sulfide is known for its pungent odor that is described as rotting eggs. The atom with the lowest electronegativity always comes in the center and that atom whose electronegativity is least among all tends to make the highest number of bonds in that molecule. As per the studies already done, the bond formed between two atoms is polar covalent if the electronegativity difference lies between 0.5 and 1.6. Sulfur dioxide has a pungent smell, often likened to the smell of a match that has just been lit. Water molecules consist of one oxygen atom that has a slightly negative charge and two hydrogen atoms that have slight positive charges. You can also read our other article on whether SO2 is polar or non-polar. Each sulfur atom has one lone pair, while each oxygen atom has two. Sulfur Dioxide (SO2) Hydrogen Sulfide (H2S) Nonpolar molecules A molecule may be nonpolar either when there is an equal sharing of electrons between the two atoms of a diatomic molecule or because of the symmetrical arrangement of polar bonds in a more complex molecule. Nonpolar molecules usually will dissolve well in nonpolar solvents, but tend to be insoluble in water. It has a molecular weight of 98.079 g/mol. The monoxide is formed as an unstable colourless gas by an electric discharge in a mixture of sulfur dioxide and sulfur vapour at low pressure; upon cooling, it condenses to an orange-red solid. All of the oxygen atoms make symmetry around the Sulfur atom. This is determined with the concept of electro-negativity. Nonpolar molecules are generally symmetrical, like the tetrahedral molecule carbon tetrachloride. Your email address will not be published. The oxygen side of the molecule has a slight negative charge, while the side with the hydrogen atoms has a slight positive charge. The polarity of a molecule is directly proportional to the difference between the electronegativities of the atoms involved in the molecule. Click on the molecule's name to see the answer, but first try to do it yourself! While SF6 is non-toxic when used properly, toxic byproducts can be produced during electrical discharges within SF6-filled equipment, posing a threat to the health of workers who come into contact with them. But the three bonds are at 120 degrees with each other and the overall polarity of SO3 gets canceled out. Most alkaline elements have a similar structure to C2H6, and for this reason, it is typically said that alkaline elements are nonpolar. The symptoms of hydrogen sulfide poisoning are similar to those of carbon monoxide poisoning; fatigue, dizziness, inability to concentrate, loss of memory, and irritability. B 2 F 3 r. carbon tetrachloride diboron trifluoride CCl 4 s. P 4 O 10 t. hydrazine tetraphosphorus decoxide N 2 H 4 u. Ammonia (NH3)isa polar molecule. In this article, I will share my information regarding the polarity of SO3 (sulfur trioxide). Hydrogen sulfide is poisonous to humans in large amounts. Then we will use VSEPR to determine the shape of the molecule and look at how the shape of the molecule allows us to determine if the entire molecule is polar or nonpolar. There is no symmetry which could cancel out the dipole charge. H2S is a slightly polar molecule because of its bent shaped geometrical structure and the small difference between the electronegativity of Hydrogen (2.2) and Sulfur (2.58) that results in a non zero dipole moment. . Essentially, polarity in chemistry is a measure of how evenly distributed electrons in a molecule are. Electronegativity, on the other hand, describes how tightly an atom attracts electrons in a bond. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Sulfur dioxide is a poisonous gas that is hazardous to human health.It can irritate the eyes, nose, throat, and lungs skin and mucous membranes.Its excessive amounts might irritate and induce inflammation in the respiratory system.Sulfur dioxide emissions in the air can lead to the creation of other sulfur oxides (SOx).SOxcan react with other compounds in the atmosphere to form small particles.These small particles may penetrate deeply into the lungs, and their sufficient quantity can contribute to health problems. The molar mass of sulfur dioxideis 64.066 g/mol. Table \(\PageIndex{1}\) shows these bonds in order of increasing polarity. SF 5 Cl - Sulfur Monochloride Pentafluoride. In fact, a large amount of hydrogen sulfide is produced via the separation of it from natural gas deposits. In contrast, water is polar because the OH bond moments do not cancel out. Its a colorless, poisonous, inorganic gas with a noxious odor similar to nitric acid. The lone pair repulsion among the Oxygen and Sulfur forms a bent shape and the angle between the bonds is found to be around 119-120 degrees. Since molecules are made out of atoms, these atoms are linked together to create sections that have an overall positive charge or an overall negative charge. Ionic bonds, like those in table salt (NaCl), are due to electrostatic attractive forces between their positive (Na+) and negative charged (Cl-) ions. So in essence, sulfur dioxide is polar while carbon dioxide is nonpolar because the individual movements of the bonds in carbon dioxide cancel one another out, yet in the case of sulfur dioxide, the angular nature of the molecule means that there is an imbalance between the poles that it has both a negative and positive side and therefore the molecule is polar. Just like with the carbon dioxide example, you not only have to take the types of atoms in a molecule of sulfur dioxide into account, you also have to take the structure of the molecule into account. Have a question? Because of the linear symmetry of the molecule, the negative charges around the oxygen atoms cancel out. This is what it means for a molecule to be polar; it has a partially charged dipole across its structure on account of the uneven spatial distribution of electrons. Save my name, email, and website in this browser for the next time I comment. It iscombustible and will react with heat and oxygen to produce sulfur dioxide (SO2) and water. Its mechanisms of action are similar to that of carbon monoxide. Thus, bonding in potassium nitrate is ionic, resulting from the electrostatic attraction between the ions K+ and \(\ce{NO3-}\), as well as covalent between the nitrogen and oxygen atoms in \(\ce{NO3-}\). Bonds between two nonmetals are generally covalent; bonding between a metal and a nonmetal is often ionic. For example, potassium nitrate, KNO3, contains the K+ cation and the polyatomic \(\ce{NO3-}\) anion. Sulfur Dioxide (American English), also known as Sulfur Dioxide (Commonwealth English), is a bond between sulfur and oxygen atoms. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Your email address will not be published. Note that noble gases are excluded from this figure because these atoms usually do not share electrons with others atoms since they have a full valence shell. However, the lone pair present on the Sulfur atom causes repulsion with the lone pair present on the Oxygen atoms resulting in the V-shape/bent-shaped SO2 molecule. For example, in the case of SO2, Oxygen has a higher electronegativity than Sulfur and it makes it polar. He chose an arbitrary relative scale ranging from 0 to 4. But due to symmetrical shape, the electronegativity difference gets canceled out. Each element has an electronegativity which is a measure of how hard they pull on electrons. Sulfur dioxide is considered a polar molecule. In a nonpolar molecule, there are no positive or negative poles formed in the molecule. In addition, due to the presence of unbonded electrons on the sulfur and oxygen atoms, SO2 has a bent shape. The electronegativity difference between sulfur (2.58) and oxygen (3.44) atoms makes it a polar molecule. Hydrogen sulfide is a triatomic (3-atom) molecule that consists of a central sulfur atom and 2 terminal hydrogen atoms. The SO2+ moiety can essentially move barrierless over the benzene ring. The electronegativity difference between sulfur (2.58) and oxygen (3.44) atoms makes it a polar molecule. The more strongly an atom attracts the electrons in its bonds, the larger its electronegativity. So even though H-S bonds are technically a little bit polar, most of the time it is safe to treat them as if they are non-polar. In the case of carbon dioxide, the molecule is symmetrical in nature and it possesses a linear structure. Also, polar solvents tend to dissolve polar solutes, and non-polar solvents dissolve non-polar solutes. Save my name, email, and website in this browser for the next time I comment. When trying to determine the polarity of a molecule, you can use a three-step process to analyze it. It is a bit denser than air and is explosive in the presence of oxygen and heat. Much like H2O, sulfur is found in the middle of the molecule, with bent bonds connecting the sulfur to the oxygen. If the difference is less than 0.5, it is considered functionally non-polar. Pauling derived the first electronegativity values by comparing the amounts of energy required to break different types of bonds. Carbon monoxide is produced in ou environment through various means like the . I am Savitri,a science enthusiast with a passion to answer all the questions of the universe. If the electrons are shared equally between the atoms then its a non-polar covalent bond. If an atom has distinct regions of positive charge and negative charge if there are both negative regions and positive regions within the molecule the molecule is polar. Basically, when we look at the lewis structure of the SO3, we see that 3 Oxygen atoms are spread around the single Sulfur atom and as a result of 2 lone pairs on each Oxygen atom they repel each other. I think you mean alkanes. This means that water is a polar molecule. Is BF3 polar or nonpolar? This unequal distribution of charges among both nitrogen and hydrogen atoms makes NH3 a polar molecule. Determine whether each of the following molecules or ions is polar or nonpolar. Learn to determine if CO (Carbon monoxide) is polar or non-polar based on the Lewis Structure and the molecular geometry (shape).We start with the Lewis Structure and look and the polarity of the individual bonds in Carbon monoxide based on the electronegativity difference between atoms. SO 3 p. disulfur dichloride sulfur trioxide S 2 Cl 2 q. For more detailed information regarding geometry, hybridization, and lewis structure of SO2, you should also refer to the article on the lewis structure of SO2. Your email address will not be published. In the liquid state, it is colorless as well as odorless and in the solid-state, it can be seen as crystalline form. That's the short answer regarding carbon dioxide's non-polarity. whereas the portion that has the sulfur atom has a slightly positive charge. The atomic number of oxygen is 8, as a result, there are 6 electrons in the vacant shell of oxygen. The greater the difference in electronegativity, the more polarized the electron distribution and the larger the partial charges of the atoms. Therefore, there is a permanent dipole moment. Intermolecular Forces Is Ammonium Ion (NH4+) Polar or Nonpolar? We all should understand that when two atoms form a bond, they basically share electrons from each other. After bonding in the SO3 molecule, the three pairs of Sulfur makes a double bond with the one pair of all three atoms of Oxygen surrounding the Sulfur atom. However, to determine if SO3 is polar we need to look at the molecular geometry or shape of the molecule.. He hopes to work on projects which bridge the sciences and humanities. Therefore, unequal charge distribution occurs after the bonding of the SO2 molecule. At the end of this reaction, the sulfate ions are reduced into hydrogen sulfide which is released into the environment. The molecule is polar covalent. However, these polyatomic ions form ionic compounds by combining with ions of opposite charge. The lone pair present on Sulfur and lone present on Oxygen atoms cause repulsion between each other. Though initially a pungent odor, the body quickly acclimates to the smell, which can make people unaware of its presence. What influences how electrons are shifted around is the bonds that exist between molecules. For example, the H and F atoms in HF have an electronegativity difference of 1.9, and the N and H atoms in NH3 a difference of 0.9, yet both of these compounds form bonds that are considered polar covalent. Paul Flowers (University of North Carolina - Pembroke),Klaus Theopold (University of Delaware) andRichard Langley (Stephen F. Austin State University) with contributing authors. The shape of H2S is bent similar to water, which is very polar. The electron affinity of an element is a measurable physical quantity, namely, the energy released or absorbed when an isolated gas-phase atom acquires an electron, measured in kJ/mol. Disulfur monoxide Cite Download Contents 1 Structures 2 Names and Identifiers 3 Chemical and Physical Properties 4 Related Records 5 Chemical Vendors 6 Literature 7 Patents 8 Classification 9 Information Sources 1 Structures 1.1 2D Structure Find Similar Structures Get Image Download Chemical Structure Depiction PubChem 1.2 3D Conformer PubChem What exactly does being a poor molecule mean? . It is also the product of processes in volcanoes and natural gas formations. Geometrical Shape: The geometrical shape of the SO3 is a trigonal planar where Sulfur is the center atom and the oxygen atom surrounds the sulfur atom at an angle of 120 degrees each. Sulfur and oxygen have a difference in electronegativity due to which polarity arises in the S-O bond but the three S-O bonds lie at 120 degrees angle with each other cancels out the overall polarity and resulting in the formation of SO3 as a nonpolar molecule. It is only found as a dilute gas phase. Thus, if you want to check if a molecule is polar or not. Updates? Covalent bonds can be polar or non-polar. Figure \(\PageIndex{1}\): The electronegativity values derived by Pauling follow predictable periodic trends with the higher electronegativities toward the upper right of the periodic table. Your email address will not be published. In SO2 molecules, the electronegative potential of oxygen is higher than that of sulfur. SO2 is polar in nature because of the difference in electronegativity between sulfur and oxygen atoms. Step 1: Draw the Lewis structure, Step 2: Draw the 3D molecular structure w/ VSEPR rules, Step 3: Use symmetry to determine if the molecule is polar or non-polar. Similarities between Sulfur and Oxygen atoms, Dissimilarities between oxygen and sulfur, Ionic Compounds| Properties, and Examples.