Problem 25 - Chemistry Matter and Change

Question

Write formulas for ionic compounds composed of the following ions. calcium and chlorate

Step-by-Step Solution

Answer

The formula is \( \text{Ca(ClO}_3)_2 \).

Step 1: Identify the Ions

The first step is to identify the ions involved. Calcium forms a cation with a charge of +2, written as \( ext{Ca}^{2+} \). Chlorate is a polyatomic anion with a charge of -1, written as \( ext{ClO}_3^- \).

Step 2: Determine the Charge Balance

To create a neutral compound, the total positive charge must balance the total negative charge. Since calcium has a +2 charge, and chlorate has a -1 charge, we need two chlorate ions to balance one calcium ion.

Step 3: Write the Chemical Formula

Now, we write down the chemical formula using the ions. Since we need two chlorate ions for every one calcium ion, the formula for the compound is \( ext{Ca(ClO}_3)_2 \). The parentheses are used to indicate that the subscript 2 applies to the entire polyatomic ion \( ext{ClO}_3^- \).

Key Concepts

Chemical Formulas

Chemical formulas are a way to represent a compound using symbols from the periodic table. They provide information about the elements present and their ratios in a compound. Chemical formulas are crucial because they help us understand the composition and properties of substances.
- The formula is made up of element symbols, which often include subscripts to denote the number of each type of atom. For example, in water, the chemical formula is \( \text{H}_2\text{O} \), which tells us there are two hydrogen atoms for every oxygen atom.
- For ionic compounds, such as those formed from calcium ions and chlorate ions, the chemical formula must show a neutral overall charge. This means balancing the positive and negative charges of the composing ions, leading to the correct ratio of ions needed to achieve charge neutrality.

Calcium Ion

The calcium ion is a cation, meaning it has a positive charge. Derived from the element calcium, this ion is commonly found in many compounds present in nature. The symbol used for calcium ion is \( \text{Ca}^{2+} \), indicating it carries a charge of +2.
- Calcium is an alkaline earth metal found in group 2 of the periodic table. It commonly loses two electrons to achieve a stable electronic configuration, resulting in its +2 charge.
- These cations are essential in various biological processes, including bone formation and nerve signaling, as they interact with different anions to form the compounds necessary for these functions.

Chlorate Ion

A chlorate ion is an oxyanion, a type of ion composed of oxygen and another element, in this case, chlorine. The chemical formula for the chlorate ion is \( \text{ClO}_3^- \). This indicates it carries a single negative charge.
- Chlorate ions are part of a group of ions that include oxygen, known as polyatomic ions, and are recognized for their role in oxidation reactions and use in explosives and disinfectants.
- In chemical formulas, the chlorate ion requires consideration for its charge, especially when forming compounds, to ensure that the positive and negative charges from ions are balanced.

Polyatomic Ions

Polyatomic ions are ions made up of two or more atoms bonded together, carrying a net charge. These ions are either negatively or positively charged and play a significant role in forming various compounds.
- They are distinct in that the atoms within a polyatomic ion are held together by covalent bonds, yet the entire group functions as a single charged entity when participating in ionic bonding.
- Examples include sulfate \( \text{SO}_4^{2-} \), nitrate \( \text{NO}_3^- \), and our focus here, chlorate \( \text{ClO}_3^- \). When writing chemical formulas, always enclose polyatomic ions in parentheses if more than one is needed to balance the charge, as in \( \text{Ca(ClO}_3)_2 \). This notation ensures that the subscript applies to the entire polyatomic ion.