Classify each compound as ionic or molecular. a. CO 2 b. NiCl 2 c. Nal d. PCl 3

All right. Hi everyone. So this question is asking us of the following compounds. Part one which ones exist as molecules and two, which ones manifest as extended structures spanning three dimensions. Here we have sodium chloride, carbon dioxide, silicone dioxide and boron tr fluoride. So let's go ahead and start with sodium chloride. Now recall that sodium chloride is an ionic compound in which sodium has a positive charge and chloride has a negative charge. No, because of this opposite charge, then both ions are going to be attracted to each other via electrostatic forces. So what that does is it creates a very regular three dimensional lattice structure because if sodium is a white circle and chloride is a black circle, then this pattern creates. But this attraction creates a sort of alternating pattern. It creates a very regular alternating pattern in which two ions of the same charge never actually interact with each other forming a very regular three dimensional lattice. Therefore, sodium chloride falls under the category described in part two here because sodium chloride manifests as an extended structure spanning three dimensions because of this electrostatic attraction. Now, by contrast, right, and carbon dioxide has linear geometry in which carbon is in the center and it has two double bonds, the two atoms of oxygen. Now, because of this linear geometry, carbon dioxide is actually nonpolar and not only is it non polar and carbon dioxide exists predominantly as a gas, right. So because of this individual molecules of carbon dioxide don't form an extended structure in the gaseous state. So while carbon dioxide is a covalent molecular compound, it doesn't form an extended structure with other molecules of co two because they're in the gaseous state, right. So there's simply too much distance between them for them to create a larger structure. So carbon dioxide primarily exists as a molecule. Now, by contrast, we have silicone dioxide and silicon dioxide exists not only as a solid but as a covalent network solid, which explains why it's found in courts, for example, right, because silicon dioxide does actually form an extended three dimensional network structure in which each atom of silicone is bound to four oxygen atoms in a tetrahedral structure. So for example, right, we've got one atom of silicone in the center and it's going to be found or bound to four different atoms of oxygen which are further bound to other atoms of silicone. And so what that does is create this sort of three dimensional lattice. Therefore, silicone dioxide does manifest as an extended structure spanning three dimensions. Now, BF three on the other hand, or boron trifle is another covalent molecular compound in which an animal boron is bound to three atoms of fluorine. Now it is trigonal planar and it is therefore, or it's trigonal planar and also nonpolar. And recall also that individual molecules of boron tr fluoride do not tend to have an extended structure, meaning that they tend to retain this configuration as BF three and they don't tend to create larger three dimensional structures the way that silicone dioxide can't, right. So boron tr fluoride predominantly exists as simply BF three and not as part of a larger network and there you have it. So here is our final answer, right. Of the four compounds listed the ones that exist as molecules are carbon dioxide and boron tr fluoride. Whereas the ones that manifest as extended structures spanning three dimensions are sodium chloride and silicone dioxide. So with that being said, thank you so very much for watching. And I hope you found this helpful.

Ch.3 - Molecules and Compounds

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Ch.3 - Molecules and Compounds

Problem 31

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Chapter 3, Problem 31

Classify each compound as ionic or molecular. a. CO₂ b. NiCl₂ c. Nal d. PCl₃

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Identify the types of elements involved in each compound. Ionic compounds typically consist of metals and nonmetals, while molecular (covalent) compounds consist of nonmetals only.

For compound a (CO2): Recognize that both carbon (C) and oxygen (O) are nonmetals. Therefore, CO2 is a molecular compound.

For compound b (NiCl2): Identify that nickel (Ni) is a metal and chlorine (Cl) is a nonmetal. This combination indicates that NiCl2 is an ionic compound.

For compound c (NaI): Note that sodium (Na) is a metal and iodine (I) is a nonmetal. This suggests that NaI is an ionic compound.

For compound d (PCl3): Observe that both phosphorus (P) and chlorine (Cl) are nonmetals. Thus, PCl3 is a molecular compound.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ionic Compounds

Ionic compounds are formed when atoms transfer electrons, resulting in the formation of charged ions. Typically, these compounds consist of a metal and a non-metal, where the metal loses electrons to become a positively charged cation, and the non-metal gains electrons to become a negatively charged anion. The electrostatic attraction between these oppositely charged ions holds the compound together.

Molecular Compounds

Molecular compounds are formed when two or more non-metal atoms share electrons through covalent bonds. These compounds consist of discrete molecules, where the atoms are held together by shared pairs of electrons. Molecular compounds often have lower melting and boiling points compared to ionic compounds and can exist in various states (solid, liquid, gas) at room temperature.

Electronegativity and Bonding

Electronegativity is a measure of an atom's ability to attract and hold onto electrons in a bond. In classifying compounds, understanding the difference in electronegativity between the atoms involved helps determine whether a bond is ionic or covalent. A large difference in electronegativity typically indicates an ionic bond, while a small difference suggests a covalent bond, which is crucial for identifying whether a compound is ionic or molecular.