maggie naming

Names and Formulas of Compounds

Introduction to Compounds

• A compound has both a name and a formula.

  • Chemical name: identifies the elements in the compound with words.

  • Chemical formula: uses symbols to represent the elements and their quantities within the compound.

  • Example: Calcium fluoride is represented as CaF₂.

Elements in a Compound

• The chemical formula allows you to test each element (subscript numbers) in a compound to identify each element and the number of atoms of each element.

• The chemical formula represents the smallest repeating part of the crystal lattice for ionic compounds.

  • Example: For calcium fluoride, CaF₂ consists of one calcium ion and two fluoride ions.

Rules for Writing the Names of Binary Ionic Compounds

Steps for Writing the Chemical Name of Ionic Compounds:

1. Name the metal (positive) ion using its name from the periodic table.

2. Name the non-metal (negative) ion using its name from the periodic table with the suffix "-ide" appended.

   • Examples:

     • Aluminum (Al) and Chlorine (Cl) = Aluminum Chloride

     • Sodium (Na) and Sulfur (S) = Sodium Sulfide

     • Potassium (K) and Oxygen (O) = Potassium Oxide

     • Magnesium (Mg) and Hydrogen (H) = Magnesium Hydride

Rules for Writing the Formulas of Binary Ionic Compounds

General Concept:

• In ionic compounds, positive and negative charges balance each other.

• This balance helps determine the ratio of positive and negative ions in the compound.

• The subscripts in formulas indicate how many of each ion are present in the compound.

Steps for Writing the Chemical Formula of Ionic Compounds:

1. Write the metal and non-metal elements in their ion form.

2. Below them, write the corresponding metal and non-metal elements again, without their ion charges.

3. Bring the number above the metal element down to the subscript position of the non-metal, and vice versa.

   • This process can be remembered with the phrase "Flip-Flop & Drop".

4. Simplify the ratio by reducing the subscripts by the common factor.

   • Note: A subscript of "1" is not shown.

   • Example: Mn₂O₄ would be simplified to MnO₂.

Example 1: Aluminum Sulfide

1. Al³⁺ S²⁻

2. A1³⁺ S²⁻

3. Flipped and Dropped: Al₂S₃

4. The formula Al₂S₃ is already in its simplest form.

Example 2: Manganese (IV) Oxide

• Compounds containing a multivalent metal need special considerations.

Multivalent Metals

• Multivalent metal: A metal that can form two or more different positive ions, hence the term "multi" indicates many possible states.

• Example: An iron ion can have a charge of 3+ or 2+.

  • The periodic table lists the different possible ion charges for each metal, with the most common ion charge listed first.

  • E.g., an iron ion can exist as Fe³⁺ or Fe²⁺.

Steps for Writing the Name of Compounds Containing a Multivalent Metal:

1. Name the metal ion with the charge indicated in brackets.

2. Below them, write the metal and non-metal elements again, without the ion charges.

3. Use "Flip-Flop & Drop" method to complete the compound formula.

4. Simplify the subscripts as necessary.

   • Example: Manganese (IV) oxide = Mn⁴⁺ O²⁻

     • Which results in Mn₂O1 after simplification.

Steps for Writing Formulas of Compounds Containing a Multivalent Metal:

1. Name the metal (using its periodic table name).

2. Determine the charge of the metal.

   • Example: In Cu₂O, the charge of Cu is +1.

3. Write the charge of the metal ion in Roman Numerals in brackets after its name.

   • E.g., Copper (II) oxide for Cu₂O.

4. Name the non-metal ion by appending the suffix "-ide" to its name.

5. Conduct a quality check to determine that the metal-to non-metal ratio is correct.

   • Ensure it coincides with the periodic table values and charge balances.

   • Example outcome: MnO = Manganese (II) oxide and Cu₂O = Copper (I) oxide.

Roman Numerals Representation

• Roman Numerals for common charges:

  • I = 1

  • II = 2

  • III = 3

  • IV = 4

  • V = 5

  • VI = 6

  • VII = 7

  • VIII = 8

Example of Charge Identification

• For Mn:

  • Mn²⁺, Mn³⁺, Mn⁴⁺.

Polyatomic Ions

1. Identify each ion and its charge (the roman numeral tells you the charge of the positive ion)

2. Below them, write the metal and the non-metal elements again, without the ion charges

3. Flip-Flop and drop

4. Use brackets around the polyatomic ion. Simplify the ratio (reduce subscripts by the common factor). DO NOT simplify inside the brackets

Example: Iron(III) hydroxide

1. Fe3+ and OH-1

2. Fe3+    OH-1

3. Fe1      (OH)3

4. Fe(OH)3

Covalent bond

• non-metal and non-metal

• form molecules

• contain covalent bonds that result from electron sharing

• Molecular compounds use a prefix system to indicate the number of atoms of each element in a single molecule of the compound

• The element furthest to the left or farthest down the periodic table, if they are in the same family, is written first

Ex: Carbon dioxide (CO2)

       Nitrogen trichloride (NCl3)

Greek Prefixes:

1. Mono-

2. Di-

3. Tri-

4. Tetra-

5. Penta-

6. Hexa-

7. Hepta-

8. Octa-

9. Nona-

10. Deca-

Writing chemical formulas for COVALENT Compounds

1. Use the periodic table to find the symbols for the 2 non-metals

5. 
   Ex: dinitrogen trioxide
   N    O

6. Check to see what number the prefix(es) stands for
   Di=2            tri=3

7. Add the prefix number as a subscript to the element it is attached to
   Answer: N2O3

Writing Names for COVALENT compounds

1. Use the periodic table to find the names of the two symbols
   EX: NF3
   nitrogen        Fluorine

2. Add the suffix “-ide“ to the second element
   Ex: nitrogen fluoride

3. Check to see what the Greek prefix is for the subscripts
   1 = mono    3 = tri

4. Add the Greek prefix to the front of the element it was attached to (mono is NEVER used for the first element)
   Answer: Nitrogen trifluoride

Note: Vowels (a,o) on the prefix are sometimes omitted if it’s followed by vowels (a,o)