Book cover for Chemistry: The Molecular Nature of Matter

Chemistry: The Molecular Nature of Matter

Neil D. Jespersen, James E. Brady, Alison Hyslop

ISBN #9781118413920

7th Edition

3,064 Questions

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53,557 Students Helped

Homework Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

This chapter provides a comprehensive framework for understanding elements, compounds, and the periodic table. Students learn to classify elements as metals, nonmetals, or metalloids, interpret chemical formulas using subscripts and coefficients, and distinguish between ionic and molecular compounds. Essential nomenclature rules, including the Stock system and Greek prefixes, are introduced to ensure clear and systematic communication in chemistry. Overall, the chapter builds fundamental skills required for problem solving in chemical reactions and compound formulation.

Learning Objectives

1

Understand and describe the organization of the periodic table, including the classification of elements into metals, nonmetals, and metalloids.

2

Explain how chemical formulas and equations express the composition and transformation of substances, emphasizing the roles of subscripts and coefficients.

3

Differentiate between ionic and molecular compounds by analyzing their formation and bonding principles.

4

Apply systematic nomenclature rules, including the Stock system and the use of Greek prefixes, to name chemical compounds accurately.

5

Develop problem-solving skills by working through examples involving chemical reactions, formula interpretation, and compound naming.

Key Concepts

CONCEPT

DEFINITION

Periodic Table

A tabular arrangement of chemical elements organized on the basis of their atomic numbers, electron configurations, and recurring chemical properties.

Metals

Elements that are typically shiny, conductive, and malleable, found on the left side of the periodic table.

Nonmetals

Elements that generally lack metallic properties and are found on the right side of the periodic table.

Metalloids

Elements that exhibit intermediary properties between metals and nonmetals.

Subscripts

Numbers written at the lower right of a chemical symbol in a formula, indicating the number of atoms of that element in the compound.

Coefficients

Numbers placed before chemical formulas in equations to indicate the number of molecules or moles of a substance involved in a reaction.

Ionic Compounds

Chemical compounds composed of positively charged ions (cations) and negatively charged ions (anions), held together by ionic bonds.

Molecular Compounds

Compounds formed when two or more nonmetal elements bond covalently, sharing electrons.

Stock System

A nomenclature system used to indicate the oxidation state of metals in ionic compounds using Roman numerals in parentheses.

Greek Prefixes

Prefixes such as mono-, di-, tri-, etc., used in the naming of molecular compounds to indicate the number of atoms of each element present.

Example Problems

Example 1

In the compounds formed by $\mathrm{Li}$, $\mathrm{Na}, \mathrm{K}, \mathrm{Rb},$ and $\mathrm{Cs}$ with chlorine, how many atoms of $\mathrm{Cl}$ are there per atom of each metal? In the compounds formed by Be, $\mathrm{Mg}$, Ca, Sr, and $\mathrm{Ba}$ with chlorine, how many atoms of $\mathrm{Cl}$ are there per atom of each metal? How did this kind of information lead Mendeleev to develop his periodic table?

Example 2

On what basis did Mendeleev construct his periodic table? On what basis are the elements arranged in the modern periodic table?

Example 3

Using their positions in the periodic table, explain why is it not surprising that strontium-90, a radioactive isotope, replaces calcium in newly formed bones.

Example 4

In the refining of copper, sizable amounts of silver and gold are recovered. Why is this not surprising?

Example 5

Why would you reasonably expect cadmium to be a contaminant in zinc but not in silver?????
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Step-by-Step Explanations

QUESTION

How do you determine the number of atoms present for each element in a compound using its chemical formula?

STEP-BY-STEP ANSWER:

Step 1: Identify the chemical symbols in the formula representing each element.
Step 2: Look at the subscript following each symbol; if no subscript is present, assume it is 1.
Step 3: Multiply any subscript by the coefficient (if the formula is part of an equation) to get the total number of atoms.
Step 4: Sum the totals for each element if needed across multiple parts of a reaction.
Final Answer: You count the atoms by reading the subscript for each element, adjusting for coefficients where applicable.

Counting Atoms in a Chemical Formula

QUESTION

How do you name an ionic compound when the metal can have more than one oxidation state?

STEP-BY-STEP ANSWER:

Step 1: Identify the metal and nonmetal in the compound.
Step 2: Determine the oxidation state of the metal, which is indicated by the charges of the ions or by the compound's formula.
Step 3: Write the name of the metal followed by its oxidation state in Roman numerals in parentheses (this is the Stock system).
Step 4: Write the name of the nonmetal by changing its ending to -ide.
Final Answer: Name the compound by citing the metal with its oxidation state in parentheses and the nonmetal as its anion with the suffix -ide.

Naming an Ionic Compound using the Stock System

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Common Mistakes

  • Confusing coefficients with subscripts when counting atoms in a chemical formula.
  • Misidentifying the type of compound (ionic vs. molecular) based on element composition alone.
  • Neglecting the proper use of the Stock system, which can result in incorrect oxidation state indicators in compound names.
  • Overlooking the role of Greek prefixes in molecular compounds, leading to ambiguous or incomplete names.