Ionic Formulas

Part of the Structure and Bonding section of Coddy's Chemistry journey. Lesson 4 of 49.

An ionic compound is neutral: its ions are in the smallest ratio whose charges cancel.

Na⁺ + Cl⁻: NaCl. Ca²⁺ + 2 Cl⁻: CaCl₂. 2 Al³⁺ + 3 O²⁻: Al₂O₃ (+6 and −6).

The subscripts count ions; the charges are not written in the formula.

Challenge

Aluminum oxide, also called alumina, is the hard white powder in sandpaper and the starting point for making aluminum metal. Combine aluminum ions and oxide ions into a neutral compound.

Try it yourself

Ion combinerMake a neutral compound

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Structure and Bonding

1Ionic Bonding

Why Atoms Bond Forming Ions The Ionic BondIonic FormulasPolyatomic Ions Ionic Lattices Recap - Salt Factory

4Polarity

Electronegativity and Bonds Polar and Non-polar Bonds Ionic or Covalent Polar Molecules When Dipoles Cancel Recap - Dipole Hunt

7Functional Groups

Carbon Chains Structural Formulas Alcohols Carboxylic Acids Esters and Ethers Aldehydes, Ketones, Amines Recap - Group Finder

2Covalent Bonds

Sharing Electrons Counting Valence Electrons Drawing Lewis Structures Double and Triple Bonds Lone Pairs Formal Charge Lewis Structures of Ions Recap - Molecule Builder

5Forces Between Molecules

London Forces Dipole-Dipole Forces Hydrogen Bonds Boiling Points Like Dissolves Like Recap - Boiling Contest

8Practice Problems

Recap - Polar Bonds Survey Recap - Pigments and Hexane Recap - Butanol and Ether Recap - Dots on an Oxide

3Shapes of Molecules

Electron Groups Linear and Trigonal Planar Tetrahedral Molecules Pyramids and Bent Molecules Bond Angles Recap - Shape Detective

6Metals and Giant Structures

Metallic Bonding Diamond and Graphite Giant Covalent Structures Four Kinds of Substance Recap - Material Match