SNC2D -- Unit C -- Nomenclature (Ionic Bonding) (1)

Ionic Bonding

• Ionic bonding is the transfer of one or more electrons from:

  • (a) a metal to a non-metal

  • (b) a metal to a group of non-metals (often includes oxygen)

Ionic Compounds

• Ionic compound: A compound composed of oppositely charged ions.

  • Identification methods:

    1. By its chemical name

    2. By its chemical formula

• IUPAC (International Union of Pure and Applied Chemistry): Standardizes naming conventions to ensure global consistency.

• Ion: A charged particle formed by the loss or gain of one or more electrons.

  • Cation: A positively charged ion

  • Anion: A negatively charged ion

Binary Compounds

• Binary compound: A compound made of a metal cation and a non-metal anion.

• Naming conventions:

  1. Positive ion (Cation): The metal cation, written first (unchanged name).

  2. Negative ion (Anion): The non-metal anion, written second, ending with the suffix –ide.

  • Examples:

    • Fluoride (F−),

    • Chloride (Cl−),

    • Oxide (O²−),

    • Sulfide (S²−),

    • Nitride (N³−),

    • Phosphide (P³−)

• Examples:

  • Magnesium & phosphorus

  • Sodium & chlorine

  • Calcium & bromine

  • Aluminum & oxygen

Chemical Formulae

Charges Method

Steps to determine chemical formula of binary ionic compounds:

1. Identify each ion and its charge:

   • Aluminum: Al³+

   • Fluorine ➔ Fluoride: F−

   • Magnesium: Mg²+

   • Nitrogen ➔ Nitride: N³−

2. Determine total positive and negative charge.

   • Example:

     • Al³+: +3

     • 3(F−): −3

     • Total: +3 + (−3) = 0

3. Note the ratio of cations to anions

   • 1 Al³+ : 3 F−

   • 3 Mg²+ : 2 N³−

4. Use subscripts to show the ratio of ions.

   • Result: AlF₃, Mg₃N₂

Crossover Method

Steps to determine chemical formula:

1. Write the ions beside each other.

   • Example: Mg²+ Cl−, Ca²+ O²−

2. Take the amount of charge (ignoring sign) from the cation and make it the subscript for the anion.

3. Take the amount of charge from the anion and make it the subscript for the cation.

   • Example: MgCl₂, CaO

4. Express the ratio in simplest form, if necessary.

Multivalent Metals

• Multivalent metal: Metals that can form different ions (commonly transition metals).

  • Examples:

    • Copper: Cu⁺, Cu²+

    • Iron: Fe²+, Fe³+

    • Tin: Sn²+, Sn⁴+

• Serialize the charge using Roman numerals in the naming (not in chemical formula).

  • Example: copper(I) oxide, iron(II) chloride.

Deduce Charge Method

Steps to name ionic compounds with multivalent metals:

1. Identify the metal.

2. Verify the metal's multiple ions.

3. Determine the ion ratio in the formula.

4. Note the anion charge and balance charges.

5. Write the metal ion charge and compound name.

Reverse Crossover Method

Steps:

1. Add charge signs for each ion.

2. Verify correctness of anion charge to determine if subscripts reduced.

3. Adjust charges as necessary based on proper anion charge.

4. Write the correct metal ion name and the compound name.

Polyatomic Ions

• Polyatomic ion: An ion made of more than one atom.

  • Names usually end with –ate or –ite. Exceptions include ammonium, hydroxide, peroxide.

• Ternary compound: A compound made of three elements.

Naming Ionic Compounds with Polyatomic Ions

1. Positive ion (Cation): Unchanged metal name.

2. Negative ion (Anion): Unchanged polyatomic group name.

   • Examples: Magnesium & phosphate, Sodium & chlorate, Calcium & hydroxide, Aluminum & nitrate

Writing Chemical Formulae with Polyatomic Ions

• Use brackets to group polyatomic ions when necessary:

  • Example: Ca(OH)₂, Mg(NO₃)₂

• Multiply numbers outside brackets with those inside for counts of elements.

Charges Method for Polyatomic Ions:

1. Identify each ion and its charge.

2. Ensure the total positive and negative charge equals zero.

3. Note the ratio and write the formula with required subscripts and brackets.