Problem 9 - Chemistry: Principles and Reactions

Question

Fill in the blanks in the following table. (a) \(\mathrm{CoCO}_{3}\) (b) \(\mathrm{LaF}_{3}\) (c) \(\mathrm{Ba}_{3}\left(\mathrm{PO}_{4}\right)_{2}\)

Step-by-Step Solution

Answer

Question: Identify the name, type, charges, and formula units for the following compounds: (a) CoCO3 (b) LaF3 (c) Ba3(PO4)2 Answer: (a) Cobalt(II) Carbonate, Ionic Compound, Co^2+ and CO3^2-, CoCO3 (b) Lanthanum(III) Fluoride, Ionic Compound, La^3+ and F^-, LaF3 (c) Barium Phosphate, Ionic Compound, Ba^2+ and PO4^3-, Ba3(PO4)2

Step 1: (a) CoCO3: Name of Compound

Cobalt(II) Carbonate

Step 2: (a) CoCO3: Type of Compound

Ionic Compound

Step 3: (a) CoCO3: Charges

Cobalt(II) has a charge of +2 (Co^2+), while carbonate (CO3) has a charge of -2 (CO3^2-).

Step 4: (a) CoCO3: Formula Unit

As the charges balance each other out, the formula unit is CoCO3.

Step 5: (b) LaF3: Name of Compound

Lanthanum(III) Fluoride

Step 6: (b) LaF3: Type of Compound

Ionic Compound

Step 7: (b) LaF3: Charges

Lanthanum(III) has a charge of +3 (La^3+), while fluoride (F) has a charge of -1 (F^-).

Step 8: (b) LaF3: Formula Unit

To balance the charges, we need three fluoride ions for each lanthanum ion; the formula unit is LaF3.

Step 9: (c) Ba3(PO4)2: Name of Compound

Barium Phosphate

Step 10: (c) Ba3(PO4)2: Type of Compound

Ionic Compound

Step 11: (c) Ba3(PO4)2: Charges

Barium (Ba) has a charge of +2 (Ba^2+), while phosphate (PO4) has a charge of -3 (PO4^3-).

Step 12: (c) Ba3(PO4)2: Formula Unit

To balance the charges, we need three barium ions and two phosphate ions; the formula unit is Ba3(PO4)2.

Key Concepts

Chemical Nomenclature

Chemical nomenclature refers to the systematic naming of chemical compounds based on their molecular composition and structure. It plays a crucial role in ensuring clear communication within the scientific community and prevents misunderstandings. In the context of ionic compounds, each name consists of two parts:

• The name of the metal (cation) comes first.
• Followed by the name of the non-metal (anion) with a suffix change to "-ide" when the anion is a simple ion.

A more complex anion, such as a polyatomic ion, retains its name without changes. For example, the compound LaF₃ is called lanthanum(III) fluoride. Here, "lanthanum(III)" indicates the +3 charge of lanthanum ions. Remember, Roman numerals denote the charge on transition metals since they can have different oxidation states. Knowing these naming conventions is fundamental as it helps us relate the compound's name to its chemical formula and vice versa. This understanding is crucial in writing and interpreting chemical equations clearly.

Chemical Formula

The chemical formula of a compound represents the types and numbers of atoms present. In ionic compounds, this formula also conveys information about the balance of charges. By understanding chemical formulas, we can deduce the compound's basic composition and its neutral charge state. For instance, with CoCO₃:

• Co represents cobalt, and CO₃ is the carbonate ion.
• Cobalt has a charge of +2, and carbonate has a charge of -2.

This balance results in the 1:1 ratio seen in CoCO₃. The process of determining the correct chemical formula involves ensuring total positive and negative charges cancel each other out. For example, in Ba₃(PO₄)₂, we have three barium ions (Ba) each with a +2 charge and two phosphate ions (PO₄) each with a -3 charge. Balancing these charges is essential to accurately reflect the stoichiometry of the compound and is pivotal in further chemical analyses or reactions.

Ionic Bonds

Ionic bonds form through the electrostatic attraction between cations (positively charged ions) and anions (negatively charged ions). This type of chemical bond occurs when one atom transfers electrons to another, resulting in the formation of ions. For example, in lanthanum(III) fluoride (LaF₃), lanthanum loses three electrons, becoming a cation (La³⁺), and each fluorine gains one electron, forming fluoride anions (F^-). The attraction between the oppositely charged ions holds the compound together. Ionic bonds are generally strong, leading to compounds with high melting and boiling points and typically solid crystalline structures. Understanding ionic bonds is critical in predicting the properties of an ionic compound and explaining how such compounds will interact with others both chemically and physically.