Atomic Ions and Ionic Compounds

Study Notes

Atomic Ions

A single atom with a positive or negative charge is called an atomic ion.
Cations: Atoms that lose one or more electrons have a positive charge.
- For example, a sodium (Na) atom loses one electron to become a sodium cation (Na+).
Anions: Atoms that gain one or more electrons have a negative charge.
- For example, a chlorine (Cl) atom gains one electron to become a chloride anion (Cl-).
Ionic Compounds: Compounds formed from the electrostatic attraction between cations and anions.
- A common example is sodium chloride (NaCl), also known as table salt.

Naming and Formulas of Ionic Compounds

Roman Numerals: Cations with multiple possible charges are designated with Roman numerals in the Stock system.
- For example: Mn2+ is manganese(II) ion.
- Note: The Roman numeral indicates the charge on the cation
Monatomic Anions: Named by changing the ending of the element's name to "-ide" and adding the word "ion".
- For example, the chlorine anion (Cl-) is called chloride ion.

Polyatomic Ions

Polyatomic ions are composed of two or more atoms bound together and carrying a net charge.
Examples: ammonium (NH4+), hydroxide (OH-), sulfate (SO42-), carbonate (CO32-).

Formulas of Ionic Compounds

Ionic compounds are formed when the total positive charge of the cations equals the total negative charge of the anions.
Steps to Determine Formulas:
1. Determine the charges of the ions involved.
2. Find the least common multiple of the charges.
3. Use subscripts to indicate the number of each ion needed to balance the charges.
Example: Aluminum oxide (Al2O3).
- Aluminum ion (Al3+).
- Oxide ion (O2-).
- The least common multiple is 6, so we need two aluminum ions (2 x 3 = 6) and three oxide ions (3 x 2 = 6).

Naming Ionic Compounds

Steps to Name Ionic Compounds:
1. Name the cation first.
2. If the cation has multiple charges, use a Roman numeral in parentheses after the cation name.
3. Name the anion second.
4. If the anion is polyatomic use the name from a table of common polyatomic ions.
Example: Iron(III) sulfate (Fe2(SO4)3)
- Iron (Fe) is the cation and has a charge of +3.
- Sulfate (SO42-) is the anion.

Oxoanions

**Oxoanions:**Polyatomic anions containing oxygen and at least one atom (the "central atom") of another element.
- Common Examples: chlorate ion (ClO3-), nitrate ion (NO3-), sulfate ion (SO42-).
Naming Oxoanions:

-ate: Base name for the ion.
-ite: One less oxygen atom than the -ate ion.
per...ate: One more oxygen atom than the -ate ion.

Example:
- The chlorate ion (ClO3-) has one less oxygen than the perchlorate ion (ClO4-).
- The chlorite ion (ClO2-) has one less oxygen atom than the chlorate ion (ClO3-).

Description

Explore the fundamentals of atomic ions, including cations and anions, as well as the formation and naming of ionic compounds. This quiz will assess your understanding of charge, ionic bonding, and the nomenclature of these important chemical species. Perfect for students studying chemistry!