Question

Name each ionic compound. a. \(\mathrm{SnCl}_{4}\) b. \(\mathrm{PbI}_{2}\) c. \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) d. \(\mathrm{Cul}_{2}\) e. \(\mathrm{HgBr}_{2}\) f. \(\mathrm{CrCl}_{2}\)

Short answer

a. Tin(IV) chloride, b. Lead(II) iodide, c. Iron(III) oxide, d. Copper(I) iodide, e. Mercury(II) bromide, f. Chromium(II) chloride

Step-by-step solution

Identify the Charge of the Metal Ion

Determine the charge of the metal ion in each compound. For Sn in (SnCl_{4}), it has a charge of +4, hence the name will have 'tin(IV)'. For Pb in (PbI_{2}), the charge is +2, leading to 'lead(II)'. Fe in (Fe_{2}O_{3}) has a charge of +3, called 'iron(III)'. Cul_{2} is incorrect because copper's (Cu) preferred charge states are +1 or +2, not iodine (I) with a subscript of 2; it should be CuI. Hg in (HgBr_{2}) has a charge of +2, named 'mercury(II)'. Cr in (CrCl_{2}) has a charge of +2, called 'chromium(II)'.

Naming Monoatomic Non-metal Ions

The non-metals in these compounds (Cl, I, O, Br) are named by taking the root of the element's name and adding the suffix '-ide'. Therefore, Cl becomes chloride, I becomes iodide, O becomes oxide, and Br becomes bromide.

Construct the Compound Names

Combine the names of the metal ions from Step 1 with the non-metal ions from Step 2. Tin(IV) chloride is (SnCl_{4}), lead(II) iodide is (PbI_{2}), iron(III) oxide is (Fe_{2}O_{3}). The incorrect compound (Cul_{2}) should be copper(I) iodide (CuI). Mercury(II) bromide is (HgBr_{2}), and chromium(II) chloride is (CrCl_{2}).

Key concepts

Charge of Metal Ions

Understanding the charge of metal ions is crucial for correctly naming ionic compounds. Metals can form ions by losing electrons, and the number of electrons they lose determines their ion's charge. This charge is typically indicated by Roman numerals in parentheses following the metal's name.

For example, when naming tin(IV) chloride, the IV indicates that tin has a charge of +4, suggesting it has lost four electrons. Similarly, lead(II) iodide implies a charge of +2 for lead. It is essential for students to recognize that some metals can have multiple oxidation states, and the correct state must be used in the name of the compound.

Naming Monoatomic Ions

Monoatomic ions are ions consisting of only one atom. When it comes to non-metals, the process of naming involves using the root of the element's name with the suffix '-ide'.

For instance, chlorine (Cl) becomes chloride, iodine (I) becomes iodide, and oxygen (O) becomes oxide when they gain electrons to form anions (negatively charged ions). This method applies strictly to the naming of non-metal ions in ionic compounds. Recognizing and applying these suffixes appropriately allows for the clear communication of the chemical formula in its name.

Compound Nomenclature

Compound nomenclature is the systematic naming of chemical compounds, and it lets chemists communicate with clarity and precision. The name of an ionic compound consists of two parts: the cation (positively charged ion) and the anion (negatively charged ion).

When forming the compound's name, one begins with the name of the metal cation, including its charge in Roman numerals if necessary, followed by the name of the non-metal anion with the '-ide' suffix. For instance, chromium(II) chloride consists of chromium with a +2 charge (hence the (II)) and chlorine as an anion.

Common Mistakes and Tips

• Always check for multiple possible oxidation states of transition metals.
• Remember to use Roman numerals to indicate the charge of metal ions.
• Do not confuse monoatomic anion naming: the suffix is always '-ide'.
• For polyatomic ions, beware that the nomenclature rules differ.

Learning to combine these rules accurately will empower students to construct the correct names for a variety of ionic compounds.