Source: CHEM106 Lab 1, NYU Chemistry
Tags: chemical formulas, compound names, ionic formulas, covalent formulas, CHEM106, NYU
Difficulty: Introductory | Prerequisites: Types and Naming of Chemical Compounds core concepts (see companion study notes).
This is the formula drill companion to the core concepts notes. It groups every compound from the lab by its metal (or central element) so you can study them in clusters rather than as an unordered list. Use it for rapid-fire formula recall: cover one column, test yourself on the other.
The metals covered are manganese (Mn), iron (Fe), magnesium (Mg) and potassium (K). The nonmetals and other elements include hydrogen, carbon, phosphorus, selenium, calcium, zinc, sodium and barium. If you can write and name every compound below from memory, you are well prepared for the lab assessment.
Compound Name | Formula | Notes |
|---|---|---|
Manganese oxide (MnO₂) | MnO₂ | Mn is +4 here; also called manganese dioxide |
Manganese chloride | MnCl₂ | Mn²⁺ with two Cl⁻ |
Manganese sulfate | MnSO₄ | Mn²⁺ with sulfate SO₄²⁻ |
Manganese heptoxide | Mn₂O₇ | Covalent naming; hepta- = 7 oxygens |
Potassium permanganate | KMnO₄ | Contains the permanganate ion MnO₄⁻ |
Manganese oxide (Mn₃O₄) | Mn₃O₄ | Mixed oxidation state oxide |
Pyrochroite | Mn(OH)₂ | Manganese(II) hydroxide; Mn²⁺ with two OH⁻ |
Methylcyclopentadienyl manganese tricarbonyl | C₉H₇MnO₃ | Organometallic compound; beyond intro scope |
Compound Name | Formula | Notes |
|---|---|---|
Iron(III) chloride | FeCl₃ | Fe³⁺ with three Cl⁻; Roman numeral required |
Iron(II) oxide | FeO | Fe²⁺ with O²⁻; simplest iron oxide |
Iron(II) chloride | FeCl₂ | Fe²⁺ with two Cl⁻ |
Compound Name | Formula | Notes |
|---|---|---|
Magnesium oxide | MgO | Mg²⁺ with O²⁻; 1:1 ratio |
Magnesium chloride | MgCl₂ | Mg²⁺ with two Cl⁻ |
Magnesium fluoride | MgF₂ | Mg²⁺ with two F⁻ |
Magnesium bromide | MgBr₂ | Mg²⁺ with two Br⁻ |
Magnesium hydroxide | Mg(OH)₂ | Mg²⁺ with two OH⁻; parentheses around OH |
Magnesium nitride | Mg₃N₂ | Three Mg²⁺ balance two N³⁻ |
Compound Name | Formula | Notes |
|---|---|---|
Potassium chloride | KCl | K⁺ with Cl⁻; 1:1 ratio |
Potassium oxide | K₂O | Two K⁺ balance one O²⁻ |
Potassium bromide | KBr | K⁺ with Br⁻ |
Potassium sulfide | K₂S | Two K⁺ balance one S²⁻ |
Potassium iodide | KI | K⁺ with I⁻ |
Potassium fluoride | KF | K⁺ with F⁻ |
Potassium nitrate | KNO₃ | K⁺ with nitrate NO₃⁻ |
Potassium hydroxide | KOH | K⁺ with OH⁻; strong base |
Potassium chlorate | KClO₃ | K⁺ with chlorate ClO₃⁻ |
Potassium selenide | K₂Se | Two K⁺ balance one Se²⁻ |
Compound Name | Formula | Notes |
|---|---|---|
Phosphoric acid | H₃PO₄ | Three H⁺ with phosphate PO₄³⁻ |
Calcium phosphate | Ca₃(PO₄)₂ | Three Ca²⁺ balance two PO₄³⁻ |
Phosphine | PH₃ | Covalent; phosphorus with three hydrogens |
Sodium phosphide | Na₃P | Three Na⁺ balance one P³⁻ |
Phosphorous acid | H₃PO₃ | Contains phosphite PO₃³⁻ |
Phosphorous trichloride | PCl₃ | Covalent naming; tri- = 3 chlorines |
Cyanide ion | CN⁻ | Polyatomic ion; carbon-nitrogen |
Calcium carbonate | CaCO₃ | Ca²⁺ with carbonate CO₃²⁻ |
Bicarbonate ion | HCO₃⁻ | Hydrogen carbonate; a polyatomic ion |
Calcium carbide | CaC₂ | Ca²⁺ with acetylide C₂²⁻ |
Carbon tetrafluoride | CF₄ | Covalent naming; tetra- = 4 fluorines |
Acetylide ion | C₂²⁻ | Diatomic anion of carbon |
Selenium dioxide | SeO₂ | Covalent naming; di- = 2 oxygens |
Sodium selenide | Na₂Se | Two Na⁺ balance one Se²⁻ |
Zinc selenide | ZnSe | Zn²⁺ with Se²⁻ |
Barium sulfide | BaS | Ba²⁺ with S²⁻ |
Sulfur pentachloride | SCl₅ | Covalent naming; penta- = 5 chlorines |
Nitrogen dioxide | NO₂ | Covalent naming; di- = 2 oxygens |
Q: Write the formula for potassium chlorate.
A: KClO₃. Potassium is K⁺; chlorate is ClO₃⁻. Charges balance 1:1.
Q: What is the name of Mg₃N₂?
A: Magnesium nitride. Three Mg²⁺ ions balance two N³⁻ ions.
Q: Write the formula for calcium phosphate.
A: Ca₃(PO₄)₂. Ca²⁺ and PO₄³⁻ cross-multiply to 3 calciums and 2 phosphates.
Q: Name the compound PCl₃ and explain which naming system you used.
A: Phosphorous trichloride. Both phosphorus and chlorine are nonmetals, so covalent (Greek prefix) naming applies. Tri- = three chlorine atoms.
Q: A student writes the formula for iron(III) chloride as FeCl₂. What went wrong?
A: The student used the wrong charge. Iron(III) means Fe³⁺, which needs three Cl⁻ to balance. The correct formula is FeCl₃. FeCl₂ would be iron(II) chloride.
Q: What is the difference between MnO₂ and Mn₂O₇?
A: MnO₂ is manganese dioxide (Mn in the +4 oxidation state). Mn₂O₇ is manganese heptoxide (Mn in the +7 state), named with a Greek prefix because it behaves as a covalent oxide.
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