Problem 66 - Chemistry: The Central Science

Question

Which of the following are ionic, and which are molecular? (a) \(\mathrm{PF}_{5}\), (b) \(\mathrm{NaI}\), (c) \(\mathrm{SCl}_{2}\), (d) \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\), (e) \(\mathrm{FeCl}_{3}\), (f) \(\mathrm{LaP}\), (g) \(\mathrm{CoCO}_{3}\), (h) \(\mathrm{N}_{2} \mathrm{O}_{4}\).

Step-by-Step Solution

Answer

(a) PF5: Molecular (b) NaI: Ionic (c) SCl2: Molecular (d) Ca(NO3)2: Ionic (e) FeCl3: Ionic (f) LaP: Ionic (g) CoCO3: Ionic (h) N2O4: Molecular

Step 1: Identify Metals and Nonmetals

Consult the periodic table and identify the metals and the nonmetals in each given substance. (a) PF5: P is a nonmetal, F is a nonmetal (b) NaI: Na is a metal, I is a nonmetal (c) SCl2: S is a nonmetal, Cl is a nonmetal (d) Ca(NO3)2: Ca is a metal, N is a nonmetal, O is a nonmetal (e) FeCl3: Fe is a metal, Cl is a nonmetal (f) LaP: La is a metal, P is a nonmetal (g) CoCO3: Co is a metal, C is a nonmetal, O is a nonmetal (h) N2O4: N is a nonmetal, O is a nonmetal

Step 2: Classify Ionic and Molecular Compounds

Determine whether each compound is ionic or molecular based on the types of elements present. (a) PF5: Molecular, as it consists only of nonmetals (P and F) (b) NaI: Ionic, as it consists of a metal (Na) and a nonmetal (I) (c) SCl2: Molecular, as it consists only of nonmetals (S and Cl) (d) Ca(NO3)2: Ionic, as it consists of a metal (Ca) and nonmetals (N and O) (e) FeCl3: Ionic, as it consists of a metal (Fe) and a nonmetal (Cl) (f) LaP: Ionic, as it consists of a metal (La) and a nonmetal (P) (g) CoCO3: Ionic, as it consists of a metal (Co) and nonmetals (C and O) (h) N2O4: Molecular, as it consists only of nonmetals (N and O)

Step 3: Results

Here are the classifications of the given compounds: (a) PF5: Molecular (b) NaI: Ionic (c) SCl2: Molecular (d) Ca(NO3)2: Ionic (e) FeCl3: Ionic (f) LaP: Ionic (g) CoCO3: Ionic (h) N2O4: Molecular

Key Concepts

Chemical Bonding

Chemical bonding refers to the force that holds atoms together in molecules or compounds. Two primary types of chemical bonding are ionic and covalent bonding. Ionic bonds form when electrons are transferred from one atom to another, usually between a metal and a nonmetal. This transfer results in the formation of positive and negative ions that attract each other. Examples include NaI and FeCl3, where metals donate electrons to nonmetals, creating strong electrostatic forces. Covalent bonds, on the other hand, occur when atoms share electrons. These bonds are usually found between nonmetallic elements. Molecules like PF5 and N2O4 form covalent bonds, as the nonmetals share electrons, allowing each atom to attain a full outer electron shell. Understanding the difference between ionic and covalent bonds is crucial for identifying compound types.

Metallic and Nonmetallic Elements

The distinction between metallic and nonmetallic elements is fundamental to chemical bonding. Metals, like sodium (Na) and calcium (Ca), are typically found on the left side of the periodic table. These elements tend to lose electrons easily, resulting in positive charges. Nonmetals, such as fluorine (F) and chlorine (Cl), are found on the right side of the periodic table. They gain electrons during chemical reactions, forming negatively charged ions. In compounds, metals and nonmetals behave differently. Metals tend to form ionic compounds by donating electrons to nonmetals, while nonmetals usually form covalent bonds by sharing electrons amongst themselves. For instance, in a compound like Ca(NO3)2, calcium donates electrons to the nitrate group, forming ionic bonds.

Periodic Table

The periodic table is an essential tool in understanding chemical elements and their interactions. Elements are organized based on atomic number, electron configuration, and recurring chemical properties. Metals, nonmetals, and metalloids are categories found on the periodic table. Each element's position reveals a lot about its chemical reactivity and bonding behavior. For example, the table helps quickly locate that sodium (Na) is a metal, whereas iodine (I) is a nonmetal. Their positions suggest that NaI will be an ionic compound because metals tend to lose electrons to nonmetals, forming ionic bonds. In summary, the periodic table not only organizes elements but also provides insight into predicting and understanding the nature of chemical bonds and compound types.