Apr 8, 2015 ... Drawing Lewis Structures · They may be making single, double or even triple bonds to the central atom giving them 2, 4 or 6 electrons ...Lewis structure of acetic acid: Acetic acid, CH3COOH, can be written out with dots indicating the shared electrons, or, preferably, with dashes representing covalent bonds. Notice the lone pairs of electrons on the oxygen atoms are still shown. The methyl group carbon atom has six valence electrons from its bonds to the hydrogen atoms because …A Lewis structure uses chemical symbols to indicate each atom and its position in a molecular structure. Lines are drawn between atoms that are bonded together ...Learn how to write Lewis symbols and structures to describe the bonding in atoms, ions, and molecules. Follow the octet rule, use single, double, and triple bonds, and apply the …Oct 15, 2023 · A Lewis diagram, also known as a Lewis structure or electron dot diagram, is a visual representation of a molecule’s arrangement of atoms and valence electrons. Atoms are represented by their chemical symbols, and valence electrons are shown as dots around the symbols or as lines between symbols representing shared electron pairs. The dot structure for sulfur dioxide has sulfur with a double bond to an oxygen on the left, and two lone pairs of electrons on that oxygen, and the sulfur with a double bond to an oxygen on the right, and two lone pairs of electrons on that oxygen. And then we have a lone pair of electrons on our sulfur.Extra electrons are added to the Lewis dot structure if the molecule is an anion (amount of electrons added = magnitude of negative charge). To account for the ...Lewis Structure Finder. Added Jun 9, 2014 by WebTester in Chemistry. This widget gets the Lewis structure of chemical compounds. Send feedback | Visit Wolfram|Alpha. Get the free "Lewis Structure Finder" widget for your website, blog, Wordpress, Blogger, or iGoogle. Find more Chemistry widgets in Wolfram|Alpha.The strength of ionic bonding depends on the magnitude of the charges and the sizes of the ions. 10.3: Lewis Structures of Ionic Compounds- Electrons Transferred is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. The tendency to form species that have eight electrons in the valence shell is …Jul 7, 2020 · This chemistry video tutorial explains how to draw the lewis structure of NO2-, the Nitrite ion.How To Draw Lewis Structures: https://www.youtube... If you’re in the market for new curtains, there’s no better time to shop than during a John Lewis curtains sale. Known for their high-quality and stylish home decor, John Lewis off...The Lewis Structure for the Salt NaCl depicts two ions with complete octets in their outer shells of electrons. As a result, there is a positive charge on ...The Lewis structure of XeF 4 indicates six regions of high electron density around the xenon atom: two lone pairs and four bonds: These six regions adopt an octahedral arrangement (Figure \(\PageIndex{6}\)), which is the electron-pair geometry. To minimize repulsions, the lone pairs should be on opposite sides of the central atom (Figure ...Ch2S Lewis Structure. CH 2 S is an organic chemical and has an atomic mass of 46.092 Da. The Chemspider ID for CH 2 S is 71446. CH 2 S is known by other names like Methanethial, Méthanethione and carbon monosulfide.. Let us learn about the different aspects of CH 2 S like hybridization, formal charge, lewis structure and bond …Figure 5.3.1 5.3. 1 The figure above shows the electron shells of He (Helium), Cl (Chlorine), and K (Potassium) as well as their Lewis dot structures below. Notice how both the electron shell and the lewis dot structures have the same number of valence electrons. The lewis dot structure ignores the nucleus and all non-valence electrons ...It is actually possible to draw another Lewis structure for nitrous oxide, where there is a double bond between both sets of atoms, rather than a triple bond and a single bond (Figure 5-10C). This pair of Lewis structures is called a pair of “resonance structures,” which are discussed in the Resonance sidebar. Drawing of Lewis structures for polyatomic ions uses the same approach, but tweaks the process a little to fit a somewhat different set of circumstances. Lewis Structures for Polyatomic Ions. Recall that a polyatomic ion is a group of atoms that are covalently bonded together and which carry an overall electrical charge. The ammonium …Those are lewis dot structures. Let's learn how... Finally, you'll understand all those weird pictures of molecules with the letters and the lines and the dots! Those are lewis dot structures. Let ...A Final Example: Lewis Structures of Ions. Try drawing the lewis structure for the oxoanion sulfite, SO2−3. Sulfur is the central atom. There are twenty-six valence electrons. Six from sulfur. Eighteen from the three oxygens. We add two more electrons because we have a negative two charge. LP=26−8(3)2=1; Write a capital S.The conveniences of working at home are also its curses. There’s no commute giving you time to settle your thoughts on the way in to work, no lunch with co-workers. To get some str...Dec 7, 2019 · Lewis structures, also known as electron dot structures, are named after Gilbert N. Lewis, who described them in a 1916 article titled, "The Atom and the Molecule." Lewis structures depict the bonds between atoms of a molecule, as well as any unbonded electron pairs. You can draw a Lewis dot structure for any covalent molecule or coordination ... The Lewis structure of a compound can be generated by trial and error. We start by writing symbols that contain the correct number of valence electrons for the atoms in the molecule. We then combine electrons to form covalent bonds until we come up with a Lewis structure in which all of the elements (with the exception of the hydrogen atoms ... An outline of how to detemine the "best" Lewis structure for an example, NO 3- is given below: 1. Determine the total number of valence electrons in a molecule 2. Draw a skeleton for the molecule which connects all atoms using only single bonds. In simple molecules, the atom with the most available sites for bondng is usually placed central.Lewis structures are structural formulas for molecules and polyatomic ions that represent all valence electrons. Since valence electrons are typically represented as dots, these structural formulas sometimes …The Lewis structure of C2, the chemical formula for diatomic carbon, is written with two Cs connected by two straight lines. Each C also contains one pair of dots, for a total of t...A Lewis structure is a graphic representation of the electron distribution around atoms. The reason for learning to draw Lewis structures is to predict the number and type of bonds that may be formed around an atom. A Lewis structure also helps to make a prediction about the geometry of a molecule.Draw Lewis structures depicting the bonding in simple molecules. Compute formal charges for atoms in any Lewis structure. Use formal charges to identify the most reasonable Lewis structure for a given molecule. Identify the oxidation states of atoms in Lewis structures. 4.1: Lewis Dot Diagrams.Figure 5.3.1 5.3. 1 The figure above shows the electron shells of He (Helium), Cl (Chlorine), and K (Potassium) as well as their Lewis dot structures below. Notice how both the electron shell and the lewis dot structures have the same number of valence electrons. The lewis dot structure ignores the nucleus and all non-valence electrons ...Jan 25, 2023 · Lewis Structure of Carbon Dioxide ( C O 2). In ( C O 2), oxygen belongs to group 16 of the Periodic Table, and carbon belongs to group 14 of the Periodic Table. Hence, oxygen has 6 valence electrons, and carbon has 4 valence electrons. Step 1- In ( C O 2) we, have C = 4 × 1 = 4 valence electrons. O = 6 × 2 = 12 valence electrons. The Lewis structure is a diagrammatic representation of determining the position of valence electrons within an atom. Moreover, the diagram helps with determining how these valence electrons participate in the bond formation either by getting accepted or donated to another atom.This type of Lewis dot structure is represented by an atomic symbol and a series of dots. See the following examples for how to draw Lewis dot structures for common atoms involved in covalent bonding. Example 1. Draw the Lewis Dot Structure for the Hydrogen atom. Since Hydrogen is in Group I it has one (1) valence electron in its shell.A step-by-step explanation of how to draw the SF4 Lewis Dot Structure (Sulfur tetrafluoride).For the SF4 structure use the periodic table to find the total n...A Lewis structure is a diagram that shows the covalent bonds and lone electron pairs in a molecule. It is based on the octet rule, which states that each atom …The Lewis structure helps us identify the bond pairs and the lone pairs. Then, with the Lewis structure, we apply the valence-shell electron-pair repulsion (VSPER) theory to determine the molecular geometry and the electron-group geometry. To identify and have a complete description of the three-dimensional shape of a molecule, we need to know …RULES FOR LEWIS STRUCTURES · 1. Determine whether the compound is covalent or ionic. · 2. Determine the total number of valence electrons available to the ...The Lewis structure is used to represent the covalent bonding of a molecule or ion. Covalent bonds are a type of chemical bonding formed by the sharing of electrons in the valence shells of the atoms. Covalent bonds are stronger than the electrostatic interactions of ionic bonds, but keep in mind that we are not considering ionic …The Lewis structure shows two single sigma bonds between the oxygen and hydrogen atoms. Besides that, these bonds leave the oxygen atom with two lone pairs of electrons. The H 2 O molecule’s hybridization is sp 3 because it has one s orbital and three p orbitals that combine to form four hybrid orbitals. Polarity of H 2 O. Water H 2 O is a polar …With 5 + 6 = 11 valence electrons, there is no way to draw a Lewis structure that gives each atom an octet of electrons. Molecules such as NO, NO 2, and ClO 2 require a more sophisticated treatment of bonding. Example 1: The \(NO\) Molecule; Draw the Lewis structure for the molecule nitrous oxide (NO). Solution. 1.Example: Lewis structure of the nitrite ion · Step one: Choose a central atom. · Step two: Count valence electrons. · Step three: Place ion pairs. · Ste...In the Lewis structures listed here, M and X represent various elements in the third period of the periodic table. Write the formula of each compound using the chemical symbols of each element: (a) (b) (c) (d) Write the Lewis structure for the diatomic molecule P 2, an unstable form of phosphorus found in high-temperature phosphorus vapor.Jan 25, 2023 · Lewis Structure of Carbon Dioxide ( C O 2). In ( C O 2), oxygen belongs to group 16 of the Periodic Table, and carbon belongs to group 14 of the Periodic Table. Hence, oxygen has 6 valence electrons, and carbon has 4 valence electrons. Step 1- In ( C O 2) we, have C = 4 × 1 = 4 valence electrons. O = 6 × 2 = 12 valence electrons. Before directly jumping into the lewis structure of SO2, let’s have a quick discussion regarding the importance of lewis structure and the steps to draw it. Lewis structure is the distribution of the electrons around the atoms of a compound. This structure helps us to know about the kind of bonds and the number of bonds that form …Lewis structures are simplistic views of molecular structure. They are based on the idea that the key to covalent bonding is electron sharing and having each atom achieve a …It is possible to draw a structure with a double bond between a boron atom and a fluorine atom in BF 3, satisfying the octet rule, but experimental evidence indicates the bond lengths are closer to that expected for B–F single bonds. This suggests the best Lewis structure has three B–F single bonds and an electron deficient boron.Learn the Kelter strategy to draw Lewis structures for molecules using the octet rule and the valence electrons of the atoms. Follow the step-by-step guide …In 1916, American chemist, Gilbert N. Lewis, introduced bond lines to electron dot structures. These structures, also known as lewis structures or electron dot structures, are drawings that visually demonstrate how electrons are shared and arranged around atoms. The electrons denoted as dots are called lone pairs and belong to an individual atom. 13. Draw the Lewis Structure for PCl 5. Sometimes, there are two or more Lewis Structures that can be drawn. For example, there are two equivalent Lewis structures for NO 2-, as shown below. Check to make sure that each is a correct Lewis structure! The possible structures are called resonance structures and are drawn with a double headed arrow ... Apr 8, 2015 ... Drawing Lewis Structures · They may be making single, double or even triple bonds to the central atom giving them 2, 4 or 6 electrons ...Working through an Example Lewis Structure Question. Our example is a question on drawing the structure of formaldehyde or H 2 CO. When the question is first opened, a box with a plus symbol is shown below the question. Just click or tap on the plus symbol to open the drawing tool. By default you start with a diatomic molecule with two place ...Steps. Use these steps to correctly draw the HCN Lewis structure: #1 First draw a rough sketch #2 Mark lone pairs on the atoms #3 Calculate and mark formal charges on the atoms, if required #4 Convert lone pairs of the atoms, and minimize formal charges #5 Repeat step 4 if needed, until all charges are minimized, to get a stable Lewis structureIn short, these are the steps you need to follow for drawing a Lewis structure: 1. Write the correct skeletal structure for the molecule. * Hydrogen atoms are always terminal (only one bond) * Put more electronegative elements in terminal positions. 2. Sum the valence electrons from all the atoms. 3.Notice that a tetrahedral molecule such as CCl4 CCl 4 is nonpolar Figure ( 4.12.1 4.12. 1. Another non polar molecule shown below is boron trifluoride, BF 3. BF 3 is a trigonal planar molecule and all three peripheral atoms are the same. Figure 4.12.1 4.12. 1 Some examples of nonpolar molecules based on molecular geometry (BF 3 and CCl 4 ).Bromine Lewis Dot Structure - Bromine is a chemical element with the atomic number 35 and the symbol Br. It is the third-lightest halogen and, at room temperature, is a volatile red-brown liquid that readily evaporates to form a similarly coloured vapour.Worked example: Lewis diagram of formaldehyde (CH₂O) The Lewis diagram of a molecule can be constructed using the following stepwise procedure: (1) Find the number of valence electrons in the molecule. (2) Draw single bonds between bonded atoms. (3) Distribute the remaining electrons throughout the molecule, keeping in mind the duet and octet ...LEARNING OBJECTIVES. Write Lewis symbols for neutral atoms and ions. Draw Lewis structures depicting the bonding in simple molecules. Thus far in this chapter, we have discussed the various types of bonds that form between atoms and/or ions. In all cases, these bonds involve the sharing or transfer of valence shell electrons between atoms. Gilbert N. Lewis introduced a diagrammatic system to represent the valence shell electrons in an atom. It helps us a lot while doing chemical bonding. He used dots to represent the valence electrons. He used lines to indicate bond between two electrons. Here's an example of carbon, with its valence electrons using Lewis dot structure. Gilbert Lewis represented the valence electrons using ... The number of electrons drawn in the structure. The number of electrons in a Lewis Structure should be equal to the number of valence electrons in the given ...Valence electronic structures can be visualized by drawing Lewis symbols (for atoms and monatomic ions) and Lewis structures (for molecules and polyatomic ions). Lone pairs, unpaired electrons, and single, double, or triple bonds are used to indicate where the valence electrons are located around each atom in a Lewis structure. Lewis structures, also known as electron dot structures, are named after Gilbert N. Lewis, who described them in a 1916 article titled, "The Atom and the Molecule." Lewis structures depict the bonds between atoms of a molecule, as well as any unbonded electron pairs. You can draw a Lewis dot structure for any covalent molecule or …Lesson 4: Dot structures and molecular geometry. Drawing dot structures. Drawing Lewis diagrams. Worked example: Lewis diagram of formaldehyde (CH₂O) Worked example: Lewis diagram of the cyanide ion (CN⁻) Worked example: Lewis diagram of xenon difluoride (XeF₂) Exceptions to the octet rule. Counting valence electrons.Lewis structures are simplistic views of molecular structure. They are based on the idea that the key to covalent bonding is electron sharing and having each atom achieve a …Jan 30, 2023 · A Lewis Structure is a very simplified representation of the valence shell electrons in a molecule. It is used to show how the electrons are arranged around individual atoms in a molecule. Electrons are shown as "dots" or for bonding electrons as a line between the two atoms. A step-by-step explanation of how to draw the CO3 2- Lewis Dot Structure (Carbonate ion).For the CO3 2- structure use the periodic table to find the total nu...In Lewis structure 2, a central xenon with 2 lone pairs is line bonded to fluorines to the left and right and line bonded to chlorines above and below. In both structures each fluorine and chlorine has 3 lone pairs. Based on the Lewis diagrams, which of the following correctly compares the polarities of compounds 1 and 2? Choose 1 answer: Choose 1 answer: …Placing one bonding pair of electrons between the O atom and each H atom gives H:O:H, with 4 electrons left over. Each H atom has a full valence shell of 2 electrons. Adding the remaining 4 electrons to the oxygen (as two lone pairs) gives the following structure: This is the Lewis structure we drew earlier.The Lewis structures of some molecules do not agree with the observed structures. For such a molecule, several dot structures may be drawn. All the dot structures contribute to the real structure. The more stable structures contribute more than less stable ones. For resonance structures, the skeleton of the molecule (or ion) …Jan 11, 2023 · 12.1: Lewis Structures. Page ID. Chemical bond refers to the forces holding atoms together to form molecules and solids. This force is of an electric nature, and the attraction between electrons of one atom to the nucleus of another atom contributes to what is known as chemical bonds. NCl3 Lewis Structure, Geometry, Hybridization, and Polarity. NCl3 is the chemical formula for Nitrogen trichloride. Also, called trichloramine it is a halogen nitride that is yellow and oily with a pungent smell. It is known as a strong explosive because being unstable in the pure form and sensitive to heat, shock, light, and any organic compound.In Lewis structure 2, a central xenon with 2 lone pairs is line bonded to fluorines to the left and right and line bonded to chlorines above and below. In both structures each fluorine and chlorine has 3 lone pairs. Based on the Lewis diagrams, which of the following correctly compares the polarities of compounds 1 and 2? Choose 1 answer: Choose 1 answer: …The NSF Lewis structure refers to the representation of the molecular structure of a compound containing nitrogen, sulfur, and fluorine atoms. It is a diagram that shows the arrangement of valence electrons and the bonds between atoms in an NSF molecule.The Lewis structure helps us understand the electron distribution and …Lewis structures are simplistic views of molecular structure. They are based on the idea that the key to covalent bonding is electron sharing and having each atom achieve a …In a Lewis Structure, electrons are represented as “dots” surrounding the central metal atom. The central metal is denoted by using its chemical symbol from the …Worked example: Lewis diagram of formaldehyde (CH₂O) The Lewis diagram of a molecule can be constructed using the following stepwise procedure: (1) Find the number of valence electrons in the molecule. (2) Draw single bonds between bonded atoms. (3) Distribute the remaining electrons throughout the molecule, keeping in mind the duet and octet ...A Lewis structure is a graphic representation of the electron distribution around atoms. The reason for learning to draw Lewis structures is to predict the number and type of bonds that may be formed around an atom. A Lewis structure also helps to make a prediction about the geometry of a molecule.Sometimes one Lewis Structure is not Enough . Some molecules or ions cannot be adequately described by a single Lewis structure. For example, drawing one Lewis structure for ozone (O 3) gives us a misleading picture of the actual bonding in the molecule.If we draw a Lewis structure for O 3 (ozone), we get this:. This structure …Jan 9, 2024 · The Lewis structure of OCS is as follows: O=C=S. In this structure, the carbon atom is in the center, bonded to both the oxygen and sulfur atoms. The oxygen and sulfur atoms each have a lone pair of electrons. The carbon-oxygen double bond and the carbon-sulfur double bond are represented by lines. A Lewis structure is a way to show the shape of a molecule. Dots show where electrons are around the atoms, and lines or pairs of dots show where covalent bonds connect the atoms. By drawing a Lewis dot structure, you can find the lone electron pairs in molecules, which helps you figure out how chemical bonds form.Jan 9, 2024 · In this article, “sulfuric acid lewis structure”, drawing the lewis structure of sulfuric acid with detailed explanations are discussed below. Sulfuric acid is an ionic compound with H+ and SO42- ion. Sulfur and oxygen have 8 and 16 electrons respectively. Among these electrons, only valance electrons or nonbonding electrons are shown ... Jul 31, 2023 · The most commonly used hand-drawn depiction is the Lewis structure:a diagram that represents atomic nuclei and core electrons by chemical symbols and valence electrons as dots or lines. A Lewis structure is built by combining Lewis diagrams (Section D3.4) of the constituent atoms. In the Lewis structures listed here, M and X represent various elements in the third period of the periodic table. Write the formula of each compound using the chemical symbols of each element: (a) (b) (c) (d) Write the Lewis structure for the diatomic molecule P 2, an unstable form of phosphorus found in high-temperature phosphorus vapor. This chemistry video tutorial explains how to draw the lewis structure of the nitrate ion NO3-.How To Draw Lewis Structures: https://www.youtube....Drawing Lewis Structures. The Lewis model of molecular electronic structure describes how atoms bond to each other. It enables us to predict whether a molecule is likely to exist, how strong it's bonds are and the number of lone pairs it has. This then enables us to work out the shape. This is a whiteboard animation tutorial on how to draw Lewis structures of molecules. This is my second tutorial in the series. The first video includes Le...
Mar 14, 2023 · This type of Lewis dot structure is represented by an atomic symbol and a series of dots. See the following examples for how to draw Lewis dot structures for common atoms involved in covalent bonding. Example 1. Draw the Lewis Dot Structure for the Hydrogen atom. Since Hydrogen is in Group I it has one (1) valence electron in its shell. . Monster high 2
Acetate (CH3COO-) ion Lewis dot structure, molecular geometry or shape, electron geometry, bond angles, hybridization, charges, polar vs nonpolar. CH 3 COO – represents the acetate anion, a polyatomic ion, the conjugate base of acetic acid (CH3COOH). Acetate salts are widely used in various biochemical processes.The Lewis structure helps us identify the bond pairs and the lone pairs. Then, with the Lewis structure, we apply the valence-shell electron-pair repulsion (VSPER) theory to determine the molecular geometry and the electron-group geometry. To identify and have a complete description of the three-dimensional shape of a molecule, we need to know …3.1: Lewis Structures. Chemical bond refers to the forces holding atoms together to form molecules and solids. This force is of an electric nature, and the attraction between electrons of one atom to the nucleus of another atom contributes to what is known as chemical bonds.What is the Lewis Structure of BaCl2? The Lewis structure of BaCl2 helps us to understand about the valence electrons that are involved in bonding in this molecule. This molecule has linear shape. This molecule contains barium and chlorine atoms. The Lewis structure of BaCl2 presents that Ba has two valence electrons, and Cl has …In 1916, American chemist, Gilbert N. Lewis, introduced bond lines to electron dot structures. These structures, also known as lewis structures or electron dot structures, are drawings that visually demonstrate how electrons are shared and arranged around atoms. The electrons denoted as dots are called lone pairs and belong to an individual atom. Apr 8, 2018 ... This organic chemistry video tutorial explains how to draw lewis structures using a simple method. Organic Chemistry - Basic Introduction: ...If you’re in the market for a new or used car in Hays, KS, chances are you’ve come across Lewis Ford Toyota. With a reputation for quality vehicles and exceptional customer service...CS lewis structure is a diatomic structure consisting of only two elements i.e. carbon atom and sulphur atom. Both C and S atoms are belongs to the 4th and 16th group of periodic table respectively. Thus both C and S atoms have 4 and 6 valence electrons in their outer valence shell orbitals. Valence electrons on C atom = 04.Drawing of Lewis structures for polyatomic ions uses the same approach, but tweaks the process a little to fit a somewhat different set of circumstances. Lewis Structures for Polyatomic Ions. Recall that a polyatomic ion is a group of atoms that are covalently bonded together and which carry an overall electrical charge. The ammonium …As Yusuf Hasan mentioned, the struggles to write a "nice" Lewis structure for this species hints at high reactivity, so I think this is the main lesson of trying to write a Lewis structure. Which of the Lewis structure is best at approximating the real situation becomes secondary, and it makes sense to move on from a Lewis structure model to ...Since the overall formal charge is zero, the above Lewis structure of CO 2 is most appropriate, reliable, and stable in nature.. Molecular Geometry of CO 2. CO 2 molecular geometry is based on a linear arrangement. The presence of a sigma bond and valence electron pairs repelling each other force them to move to the opposite side of the carbon …Lewis structure of acetic acid: Acetic acid, CH3COOH, can be written out with dots indicating the shared electrons, or, preferably, with dashes representing covalent bonds. Notice the lone pairs of electrons on the oxygen atoms are still shown. The methyl group carbon atom has six valence electrons from its bonds to the hydrogen atoms because …Lewis diagrams. Google Classroom. You might need: Periodic table. Ethanethiol, C A 2 H A 6 S , is a clear liquid with a strong odor. The compound is often added to otherwise odorless fuels such as natural gas to help warn of gas leaks. The skeletal structure of ethanethiol is shown below.4.7: Drawing Lewis Structures is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by LibreTexts. Molecules can be represented using Lewis structures, which show how electrons are arranged around the atoms in a molecule as bonded pairs of electrons (bonds) and lone pairs of electrons. These ….Figure 5.3.1 5.3. 1 The figure above shows the electron shells of He (Helium), Cl (Chlorine), and K (Potassium) as well as their Lewis dot structures below. Notice how both the electron shell and the lewis dot structures have the same number of valence electrons. The lewis dot structure ignores the nucleus and all non-valence electrons ...The strength of ionic bonding depends on the magnitude of the charges and the sizes of the ions. 10.3: Lewis Structures of Ionic Compounds- Electrons Transferred is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. The tendency to form species that have eight electrons in the valence shell is ….