Question

Given the chemical formulas of the following compounds, name each compound and state the rules you used to determine each name. KI, Fe2O3, (NH4)3PO4

Answer 1

Answer:

1.) KI

-------> potassium iodide

Potassium (K⁺) is a metal and iodine (I⁻) is a nonmetal. Therefore, when naming, there are no prefixes denoting how many of each element is in the compound. Because potassium is listed first in the compound, it must be the cation. Because iodine is listed second, it must be the anion. Anions in naming have their endings dropped and have the suffix -ide added.

2.) Fe₂O₃

-------> iron(III) oxide

Iron (Fe³⁺) is a metal and oxygen (O²⁻) is a nonmetal. Therefore, when naming, there are no prefixes denoting how many of each element is in the compound. Because iron is listed first, it is the cation and oxygen is the anion. Both of the elements have charges that do not balance each other (denoted by the subscripts). Because iron can have multiple different charges, the charge of iron (+3) should be listed when naming.

3.) (NH₄)₃PO₄

-------> ammonium phosphate

Ammonium (NH₄⁺) and phosphate (PO₄³⁻) are both polyatomic ions. When these ions bond, they also don't have quantity prefixes. Ammonium is the cation and phosphate is the anion. No roman numerals are necessary because the polyatomic ions always have a particular charge.