Question

The formula for calcium chlorite is (a) \(\mathrm{CaClO}_{2}\) (b) \(\mathrm{Ca}\left(\mathrm{ClO}_{2}\right)_{2} ;(\mathrm{c}) \mathrm{CaClO}_{3} ;(\mathrm{d}) \mathrm{Ca}\left(\mathrm{ClO}_{4}\right)_{2}\)

Short answer

The correct formula for calcium chlorite is (b) Ca(ClO2)2.

Step-by-step solution

Identify the charge of calcium ion

Calcium (Ca) is a Group 2 element in the periodic table, and it forms ions with a +2 charge when it loses its outer two electrons.

Identify the charge of Chlorite ion

The Chlorite (ClO2) is a polyatomic ion with a charge of -1.

Balance charges to form a neutral compound

In order to form a neutral compound, the total charges from the cation (positive ion) and the anion (negative ion) have to add up to 0. In this case, since Calcium has a charge of +2 and Chlorite has a charge of -1, two chlorite ions are needed to balance out the charge of one calcium ion. Thus, the chemical formula for calcium chlorite is Ca(ClO2)2.

Key concepts

Ionic Compounds

Ionic compounds are formed when metals and non-metals exchange electrons to achieve stable electronic configurations. Metals, which are typically found on the left side of the periodic table, tend to lose electrons and form positive ions, or cations. Non-metals, located on the right side, gain these electrons to become negative ions, or anions. This creates a bond due to the electrostatic attraction between the oppositely charged ions. Calcium chlorite, for example, consists of calcium (a metal) and chlorite (a non-metal ion). The ionic nature of these components leads them to combine in specific ratios that ensure neutrality for the compound.

When forming an ionic compound, it is crucial to consider the valency or charge of the ions involved. A balance must be achieved so that the total positive charge equals the total negative charge, resulting in a neutral compound. Therefore, in calcium chlorite, two chlorite ions (each with a -1 charge) balance out one calcium ion (with a +2 charge).

In summary, ionic compounds involve:

• Formation from metals and non-metals
• Charges that must balance out to form a neutral compound
• Electrostatic attraction between ions

Polyatomic Ions

Polyatomic ions are ions that contain more than one atom. Unlike single-atom ions, polyatomic ions integrate multiple atoms bonded together, yet they collectively possess a charge, either positive or negative. The chlorite ion \(ClO_2^-\) is an example of a polyatomic ion. It consists of one chlorine atom and two oxygen atoms, and overall, it carries a -1 charge.

These complex ions function just like monatomic ions in chemical reactions, meaning they partner with cations or other anions to form compounds. When writing chemical formulas, the polyatomic ions are often placed inside parentheses to signify that the entire group retains its charge as a whole. For example, in calcium chlorite, the correct formula is written as Ca(ClO_2)_2 to reflect that two chlorite ions are needed to balance the charge of one calcium ion.

Key characteristics of polyatomic ions include:

• Composed of multiple atoms
• Carry a specific charge
• Often coordinate with metals to form ionic compounds

Balancing Chemical Equations

Balancing chemical equations is an essential skill in chemistry used to reflect that matter is neither created nor destroyed in any chemical reaction. This process ensures that the number of atoms of each element is the same on both the reactant and product sides of the equation.

In the formation of calcium chlorite, the balancing involves determining the right amount of each type of ion to ensure electrical neutrality. While the equation itself isn't explicitly a chemical reaction equation, the principle of balance applies to the ionic charges as well. Since one calcium ion holds a +2 charge and each chlorite ion holds a -1 charge, exactly two chlorite ions are needed to balance one calcium ion.

Balancing equations can be summarized in the following steps:

• Write the skeleton equation with all reactants and products
• Use coefficients to ensure the same number of each type of atom on both sides
• Verify that the total charge is the same on both sides if ions are involved

By understanding how to balance both chemical equations and charge, students can successfully predict and verify chemical formulas for compounds like calcium chlorite.