Chapter_03_1_.

Chapter 3: Chemical Compounds Overview

Chemical compounds can be broadly categorized into ionic and molecular compounds, each with distinct properties and structures. Understanding these categories aids in predicting their behavior in reactions and solutions.

Key Questions for Consideration

• Ionic vs. Molecular Compounds: Differences in structure and properties.

• Types of Ions: Identify the types of ions present in ionic compounds.

• Formulas Representation: What do the formulas for ionic compounds indicate?

• Nomenclature of Ionic Compounds: Naming conventions for ionic compounds.

• Molecular Compound Formulas: Insight into the formulas and naming for molecular compounds.

• Common Acids and Bases: Basic understanding and nomenclature for common acids and bases.

• Classification Through Names: How do compound names communicate classification and properties?

Topics Covered

• Ionic and Molecular Compounds

• Monatomic and Polyatomic Ions

• Formulas for Ionic Compounds

• Naming Ionic Compounds

• Naming and Writing Formulas for Molecular Compounds

• Acids and Bases

• Predicting Properties and Naming Compounds

3.1 Ionic and Molecular Compounds

• Electrical Conductivity of Water: Water conducts electricity due to the presence of ions, which dissociate from ionic compounds when dissolved. This is crucial for various biological and chemical processes.

• Dissociation of Ions: In solutions containing ionic compounds, ions separate and allow current to pass through, enabling the flow of electric charge, which is essential in many fields including electrochemistry and biochemistry.

Electrolytes and Nonelectrolytes

• Electrolytes:

  • Definition: Substances that release ions in water.

  • Function: Conduct electricity through dissociation (ionization).

• Nonelectrolytes:

  • Definition: Substances that do NOT dissociate in water and do NOT conduct electricity (e.g., methanol, glucose).

Electrolyte Classification

• Strong Electrolytes: Completely dissociate into ions when dissolved in water, such as NaCl (sodium chloride) and HCl (hydrochloric acid).

• Weak Electrolytes: Only partially dissociate; for example, acetic acid (CH3COOH) does not completely ionize in solution.

Properties of Ionic vs. Molecular Compounds

Distinction between Ionic and Molecular Compounds

• Examples:

  • Ionic: NaCl (sodium chloride)

  • Molecular: CO2 (carbon dioxide), O2 (oxygen).

Activities: Identification and Comparison

• Identify Compounds: Classify examples like CCl4 (molecular) and CaF2 (ionic).

• Comparative Properties Activities: Identify which among given compounds has the highest melting, boiling points, or density.

3.2 Monatomic and Polyatomic Ions

• Monoatomic Ions: Ions derived from a single atom.

  • Common Monoatomic Ions: Learn the charges (e.g., Na+, Cl−, Mg2+).

• Polyatomic Ions: Ions composed of multiple atoms with a net charge..

  • Examples: Sulfate (SO4^2−), Nitrate (NO3^−).

Naming Polyatomic Ions

• Names change based on the number of oxygen atoms:

  • Oxoanions: For instance, Nitrate (NO3^−) has one more oxygen than Nitrite (NO2^−).

3.3 Formulas for Ionic Compounds

• Net Charge: The formula must be neutral with equal positive and negative charges.

• Formula Unit: Represents the simplest ratio of ions in the compound.

Writing and Naming Ionic Formulas

• Rules: Careful construction of formulas is necessary to ensure charge neutrality; this involves balancing the charges of cations and anions.

Activities: Naming Ionic Compounds

• Practice: Name ionic compounds based on their formulas (e.g., NaCl -> sodium chloride).

Naming Ionic Compounds with Variable Charges

• Transition Metals: Differentiate using Roman numerals for their charges in compounds (e.g., FeCl2 -> iron(II) chloride).

3.5 Naming Molecular Compounds

• Naming Rules: Involve the use of Greek prefixes to indicate the number of atoms (e.g., CO2 -> carbon dioxide).

Naming Acids

• Binary Acids: Names start with hydro- for compounds containing hydrogen with nonmetals (e.g., HCl -> hydrochloric acid).

• Oxoacids: Naming based on the oxoanion involved, with modifications (e.g., -ate becomes -ic, -ite becomes -ous).

Predicting Properties and Naming Compounds

• Classification: Determine the type of compound before proceeding to name it, considering whether it is ionic, molecular, or an acid.

Practice Activities

• Tasks: Engage in activities related to naming and writing formulas for various compounds, enhancing understanding through exercises.