Question

Name the following substances: (a) \(\mathrm{MgCO}_{3}\) (b) \(\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}\) (c) \(\mathrm{AgCN}\) (d) \(\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\)

Short answer

(a) Magnesium carbonate (b) Calcium acetate (c) Silver cyanide (d) Sodium dichromate

Step-by-step solution

Identify the Compound Type (a)

The compound \(\mathrm{MgCO}_{3}\) is an ionic compound consisting of a metal (magnesium) and a polyatomic ion (carbonate). To name this compound, we name the metal first followed by the name of the polyatomic ion.

Name the Compound (a)

The metal is magnesium, and the polyatomic ion is carbonate. Therefore, the name of \(\mathrm{MgCO}_{3}\) is magnesium carbonate.

Identify the Compound Type (b)

The compound \(\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}\) is an ionic compound consisting of a metal (calcium) and a polyatomic ion (acetate). To name this compound, we name the metal first followed by the name of the polyatomic ion.

Name the Compound (b)

The metal is calcium, and the polyatomic ion is acetate (\(\mathrm{CH}_{3} \mathrm{CO}_{2}^{-}\)). Therefore, the name of \(\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}\) is calcium acetate.

Identify the Compound Type (c)

The compound \(\mathrm{AgCN}\) is an ionic compound consisting of a metal (silver) and a polyatomic ion (cyanide). To name this compound, we name the metal first followed by the name of the polyatomic ion.

Name the Compound (c)

The metal is silver, and the polyatomic ion is cyanide. Therefore, the name of \(\mathrm{AgCN}\) is silver cyanide.

Identify the Compound Type (d)

The compound \(\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) is an ionic compound consisting of a metal (sodium) and a polyatomic ion (dichromate). To name this compound, we name the metal first followed by the name of the polyatomic ion.

Name the Compound (d)

The metal is sodium, and the polyatomic ion is dichromate. Therefore, the name of \(\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) is sodium dichromate.

Key concepts

Magnesium Carbonate

Magnesium carbonate is an interesting ionic compound often encountered in chemistry. It consists of the metal magnesium (Mg) and the polyatomic ion carbonate (CO₃²⁻). Naming this compound follows a straightforward process:

• The first step is to recognize that it is an ionic compound, meaning it is formed from a combination of metal and non-metal ions.
• The metal is always named first, which in this case, is magnesium.
• Next, identify the polyatomic ion. Here, it is carbonate.
• Combine the names: magnesium + carbonate = magnesium carbonate (\(\text{MgCO}_3\)).

Magnesium carbonate naturally occurs in minerals such as magnesite and dolomite. It's frequently used as an antacid and in some supplements. Understanding its composition helps sense its diverse applications.

Calcium Acetate

Calcium acetate is another example of an ionic compound featuring a transition metal paired with a polyatomic ion. Here’s how you can identify and name it:

• Firstly, recognize the formula \(\text{Ca(CH}_3\text{CO}_2)_2\) indicates an ionic bond between calcium and acetate.
• Calcium is a metal and serves as the cation in this case.
• The polyatomic ion here is acetate (\(\text{CH}_3\text{CO}_2^-\)).
• The naming convention is the metal first, followed by the polyatomic ion: calcium + acetate = calcium acetate.

Calcium acetate is useful in removing phosphorus from wastewater and as a food additive. Its structure is vital to its role in various industrial and healthcare applications.

Silver Cyanide

Silver cyanide is an ionic compound composed of silver (Ag) and the cyanide ion (CN⁻). To name this compound, one should:

• Look at the compound’s formula \(\text{AgCN}\) and note that it is an ionic compound.
• Identify silver as the metal component, which is common in precious metal ion compounds.
• The polyatomic ion in this case is cyanide.
• By convention, name the metal first followed by the polyatomic ion: silver + cyanide = silver cyanide.

Silver cyanide is mainly used in silver plating. Its toxic nature requires careful handling, which is essential knowledge for safe usage.

Sodium Dichromate

Sodium dichromate is a vibrant orange ionic compound that includes sodium (Na) and the polyatomic ion dichromate (Cr₂O₇²⁻). To break down the naming process:

• Start with recognizing it as an ionic compound indicated by \(\text{Na}_2\text{Cr}_2\text{O}_7\).
• The metal sodium acts as the cation in the structure.
• Identify dichromate as the polyatomic ion present in this compound.
• Adhere to the naming rule by placing the metal name first, followed by the polyatomic ion: sodium + dichromate = sodium dichromate.

Sodium dichromate is utilized in dye manufacturing and serves as a corrosion inhibitor. Awareness of its function and hazardous characteristics is crucial for its effective and safe use.