How to write the Formula for Calcium Nitrate?
The Correct Answer and Explanation is :
The formula for calcium nitrate is Ca(NO₃)₂.
Explanation:
Calcium nitrate is an ionic compound that consists of calcium ions (Ca²⁺) and nitrate ions (NO₃⁻). To write its formula, you must balance the charges between these ions to create a neutral compound. Here’s a step-by-step guide to understanding how to derive the correct formula for calcium nitrate:
- Calcium Ion (Ca²⁺): Calcium belongs to the alkaline earth metals in Group 2 of the periodic table. The general charge for calcium ions is +2 (Ca²⁺), meaning each calcium ion carries a +2 charge.
- Nitrate Ion (NO₃⁻): The nitrate ion is a polyatomic ion consisting of one nitrogen atom covalently bonded to three oxygen atoms, with an overall charge of -1 (NO₃⁻). Nitrate is a common anion in many ionic compounds, and its charge is always -1.
- Balancing the Charges: To form a neutral compound, the total positive charge must equal the total negative charge.
- One calcium ion (Ca²⁺) has a +2 charge.
- To balance this, you need two nitrate ions (NO₃⁻), since each nitrate ion has a -1 charge. Two nitrate ions will give a total charge of -2.
- Writing the Formula: Since one calcium ion pairs with two nitrate ions, the chemical formula for calcium nitrate is Ca(NO₃)₂. The calcium ion is written first, followed by the nitrate ion in parentheses to indicate the two nitrate ions.
Important Notes:
- Polyatomic Ions: The nitrate ion is a polyatomic ion, meaning it consists of more than one atom (N and O). It is treated as a single unit when writing formulas.
- Subscripts: The subscript “2” next to the nitrate ion indicates that two nitrate ions are needed to balance the charge of one calcium ion.
Calcium nitrate is commonly used in fertilizers, where it provides a source of both calcium and nitrogen for plant growth.