Inorganic Chemical Nomenclature

Inorganic Chemical Nomenclature in the Stock System Tutorial

Introduction to Chemical Nomenclature

Why is Chemical Nomenclature Important?

• Understanding correct terminology is essential for learning chemistry.
• Proper nomenclature is key for expressing oneself professionally in the sciences.
• It is critical for comprehending scientific literature in related fields.

Overview of Inorganic Nomenclature

• Learning basics of inorganic nomenclature can be confusing for many students.
• The aim is to clarify and make it easier to understand.

Learning Objectives

Topics Covered

1. Classifying chemical compounds
2. Naming ionic compounds
3. Naming covalent compounds
4. Naming acids and other compound types

IUPAC Rules for Nomenclature

Background

• The International Union of Pure and Applied Chemistry (IUPAC) established rules for naming compounds.
• These rules were first set in 1940 and are still used today.

Focus on Inorganic Compounds

• Inorganic compounds generally do not contain carbon, with some exceptions.
• Exceptions include carbon dioxide (CO₂) and carbonates that contain the carbonate ion (CO₃²⁻).

Comparison: Inorganic vs Organic Compounds

Classification of Compounds

Steps for Classification

1. Determine if the chemical formula begins with a metal or ammonium (NH₄⁺).
   • If yes, classify as ionic.
   • If no, classify as covalent.
2. If covalent, check if it contains hydrogen and is in an aqueous solution.
   • If yes, classify as an acid.
   • If no, classify as a covalent molecular compound.

Ionic Compounds

Classification of Ionic Compounds

• Binary Ionic Compounds: Contain two elements (one metal, one nonmetal).
  • Examples: NaCl, AlCl₃
• Ternary Ionic Compounds: Contain three elements, including at least one metal and one nonmetal.
  • Examples: KNO₃, Al(NO₃)₃

Molecular Compounds

• No metal ions are present in the formula.

Binary Molecular Compounds

• Simplest binary molecular compounds contain two nonmetals.
  • Examples: NH₃ (ammonia), H₂O (water).

Aqueous Acids

• Molecular compounds that can ionize in water.

Classification of Aqueous Acids

• Binary Acids: Compounds with hydrogen and another nonmetal.
  • Example: HCl (aq) is a binary acid.
• Ternary Oxyacids: Compounds containing hydrogen, oxygen, and another element.
  • Example: HNO₃ (aq) is a ternary oxyacid.

Distinguishing Between Ionic and Molecular Compounds

Ionic Compounds

• Composed of cations (usually metals) and anions (usually nonmetals).
• Basic unit is the formula unit (smallest electrically neutral collection of ions).
  • Example: NaCl contains Na⁺ and Cl⁻ in a 1:1 ratio.

Molecular Compounds

• Composed of covalently bonded nonmetals.
• Basic units are molecules.
  • Examples: H₂O (water), CO₂ (dry ice), C₃H₈ (propane).

Naming Ions in Ionic Compounds

Classification of Cations

• Type 1 Cations: Have one possible charge.
• Type 2 Cations: Can have multiple possible charges.

Predicting Monoatomic Cation Charges

• Group IA/1 metals form 1+ ions.
• Group IIA/2 metals form 2+ ions.
• Group IIIA/13 metals typically form 3+ ions.
• Not all charges are predictable; for instance, tin and lead can form two types of ions (2+ and 4+).

Specific Type 1 Cations

• Examples include:
  • Zn²⁺, Ag⁺, Na⁺, Mg²⁺, Al³⁺.

Naming Type 1 Cations

• Named for the parent atom followed by “ion.”
  • Example: Na⁺ is sodium ion, Mg²⁺ is magnesium ion.

Naming Type 2 Cations

• Must specify the charge with Roman numerals.
  • Examples: Cu⁺ is copper(I) ion, Cu²⁺ is copper(II) ion, Fe²⁺ is iron(II) ion, Fe³⁺ is iron(III) ion.

Alternative Naming for Type 2 Cations

• Latin prefixes followed by -ous or -ic.
• Lower charge gets -ous; higher charge gets -ic.
  • Examples: Cu⁺ is cuprous ion; Cu²⁺ is cupric ion.

Naming Monoatomic Anions

• Base names for nonmetals end with -ide.
• All anions have one possible charge.

Naming Polyatomic Ions

• Polyatomic ions consist of groups covalently bonded with an overall charge.
• Examples:
  • NaNO₃ consists of Na⁺ and NO₃⁻.
  • CaCO₃ consists of Ca²⁺ and CO₃²⁻.

Oxyanions

• Most polyatomic ions are oxyanions.
• Naming based on the number of oxygen atoms:
  • More oxygens = -ate; fewer oxygens = -ite.
  • Examples: NO₃⁻ (nitrate), SO₄²⁻ (sulfate).

Oxyanion Series with Prefixes

• If more than two ions: hypo- (less than), per- (more than).
  • Examples: ClO⁻ (hypochlorite), ClO₄⁻ (perchlorate).

Naming Ionic Compounds

General Rules

• Composed of metals and nonmetals.
• Begin with metals or ammonium (NH₄⁺).
• Examples include NaBr, Al₂(CO₃)₃.

Naming Binary Ionic Compounds (Type 1)

• Contains two different elements.
  • Example: KCl is potassium chloride; CaO is calcium oxide.

Naming Type 2 Binary Ionic Compounds

• Charge written in Roman numerals.
  • Example: Fe²⁺ is iron(II); Fe³⁺ is iron(III).

Naming Ionic Compounds with Polyatomic Ions (Ternary)

• Use polyatomic ion names as needed.
  • Example: NaNO₂ is sodium nitrite.

Hydrated Ionic Compounds

• Compounds with associated water molecules.
• Example: Epsom salts MgSO₄•7H₂O is magnesium sulfate heptahydrate.

Common Prefixes for Hydrated Ionic Compounds

Molecular Compounds

Characteristics

• Non-metals only, no ionic nature.
• Focus on simple binary inorganic compounds and binary/ternary acids.

Rules for Naming Molecular Compounds

• No charge assignments.
• Group elements based on the periodic table.
• Use prefixes based on the number of atoms present.
• If hydrogen is present, prefixes can often be omitted.

Binary Molecular Compounds and Prefixes

Examples of Molecular Compounds

• CO is carbon monoxide; CO₂ is carbon dioxide; N₂O₄ is dinitrogen tetroxide; P₄O₁₀ is tetraphosphorus pentoxide.

Acids

Characteristics of Acids

• Acids ionize in water and release hydrogen ions (H⁺).
• Must contain hydrogen, one or more nonmetals, and be soluble in water.

Classification of Acids

1. Binary Acids: Two-element compounds, a hydrogen cation and one nonmetal anion.
2. Oxyacids: Hydrogen cation and an oxyanion.

Naming Binary Acids

• Use "hydro-" prefix.
• Change nonmetal name to -ic.
• Add the word "acid."
  • HCl(aq) is hydrochloric acid.

Naming Oxyacids

• If polyatomic ion ends in -ate, use -ic.
• If polyatomic ion ends in -ite, use -ous.
• Add the word "acid."
  • H₂SO₄ is sulfuric acid, H₂SO₃ is sulfurous acid.

Summary Examples of Acids

• HCl(aq) is hydrochloric acid; H₂SO₄ is sulfuric acid; H₂SO₃ is sulfurous acid.

Inorganic Nomenclature Flow Chart

Final Recap of Inorganic Naming Processes:

• IONIC:
  • Metal and nonmetal -> Type 1 or Type 2
  • For Type 1: Name of metal + base name of nonmetal + -ide
  • For Type 2: Name of metal + (charge in Roman numerals) + base name of nonmetal + -ide
• MOLECULAR:
  • Nonmetals only (prefixes used)
• ACIDS:
  • Binary or Oxyacids (specifiers for naming)

Writing Formulas of Compounds

General Principles

• To write formulas based on names, apply principles of nomenclature back in reverse.

Writing Formulas for Ionic Compounds

• Identify charge of ions using the periodic table.
• Use lowest number of each ion to cancel charges to zero.

Examples of Writing Formulas for Ionic Compounds

• Potassium chloride is KCl (one of each ion).
• Sodium sulfate is Na₂SO₄ (two sodium ions for one sulfate).
• Iron(III) bromide is FeBr₃ (three bromide ions balance iron(III) charge).

Writing Formulas for Molecular Compounds

• Use prefixes for the number of each element.
• Examples: Carbon tetrachloride is CCl₄; Dinitrogen pentoxide is N₂O₅.

Writing Formulas for Acids

• If it ends in "acid," start with H.
• Use ionic principles: hydro- for binary, -ate/-ite rules for oxyacids.
  • Hydroiodic acid is HI; Perchloric acid is HClO₄; Chromic acid is H₂CrO₄.

Additional Resources

• "How to Speak Chemistrian. Crash courses #11."
• "Chemical Nomenclature. Dr. Causey."
• Various other video resources for further study.

Conclusion

• The principles of inorganic chemical nomenclature are essential for clear communication in chemistry. Being able to classify and name compounds confidently contributes to successful learning and application of chemistry in practical and academic settings.