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Ch.8 - Basic Concepts of Chemical Bonding
Chapter 8, Problem 45c

In the following pairs of binary compounds, determine which one is a molecular substance and which one is an ionic substance. Use the appropriate naming convention (for ionic or molecular substances) to assign a name to each compound: (c) PbCl4 and RbCl.

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Identify the types of elements in each compound: PbCl4 contains lead (Pb) and chlorine (Cl), while RbCl contains rubidium (Rb) and chlorine (Cl). Lead is a metal and chlorine is a nonmetal; similarly, rubidium is a metal and chlorine is a nonmetal.
Determine the type of bonding and compound classification: Metals bonding with nonmetals typically form ionic compounds due to the transfer of electrons from the metal to the nonmetal. Therefore, both PbCl4 and RbCl are likely to be ionic compounds.
Check the nature of the metal: Pb (lead) can form more than one type of ion (Pb2+ and Pb4+), which is typical in ionic compounds with transition and post-transition metals. Rb (rubidium) forms a single type of ion (Rb+), typical of alkali metals in ionic compounds.
Assign the correct names using ionic naming conventions: For PbCl4, since lead can have multiple oxidation states, specify the oxidation state of lead in the name. For RbCl, rubidium forms only one common ion, so no specification of the charge is needed.
Final names: PbCl4 is named lead(IV) chloride, indicating that lead is in the +4 oxidation state. RbCl is named rubidium chloride, indicating the +1 oxidation state of rubidium.

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Key Concepts

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

Ionic vs. Molecular Compounds

Ionic compounds are formed from the electrostatic attraction between positively and negatively charged ions, typically between metals and nonmetals. In contrast, molecular compounds consist of molecules formed by covalent bonds, where atoms share electrons, usually between nonmetals. Understanding the distinction helps in identifying the nature of the compounds in question.
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Naming Ionic Compounds

Ionic compounds are named by stating the cation (positive ion) first, followed by the anion (negative ion). The cation retains its elemental name, while the anion's name is derived from its element with an '-ide' suffix for simple ions. For example, in RbCl, rubidium (Rb) is the cation and chlorine (Cl) becomes chloride.
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Naming Molecular Compounds

Molecular compounds are named using prefixes to indicate the number of atoms of each element present in the molecule. The first element retains its name, while the second element's name is modified to include an '-ide' suffix. For instance, PbCl4 is named lead(IV) chloride, indicating the presence of four chloride ions associated with lead.
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