Chem Explorers

Exploring Calcium Carbonate: From Lewis Structure to Industrial Uses

The Wonders of Calcium Carbonate and its Lewis Structure

Calcium carbonate (CaCO3) is an ionic compound with well-defined features that make it important in various fields of science. From its Lewis structure to its physical properties, this compound has a lot to offer, and this article aims to educate readers on the nitty-gritty of calcium carbonate.

Drawing the Lewis Structure of CaCO3

The Lewis structure of CaCO3 involves the distribution of valence electrons within its constituent atoms. Carbon has four valence electrons, while oxygen has six, meaning that each oxygen atom bonds with two electrons from carbon to form a double bond.

Additionally, the presence of a Ca ion completes the octet of every oxygen atom in the compound. As a result of this process, the CaCO3 molecule has a total of 24 electrons.

Resonance and Lone Pairs

The distribution of electrons and the presence of lone pairs in CaCO3 molecules result in the resonance of the molecule. The phenomenon of resonance accounts for the ability of the compound to manifest differing electronic or molecular structures while retaining its physical and chemical properties.

Shape and Angle

The shape of the CaCO3 molecule is Triagonal Pyramid, making its symmetry lower than the theoretically defined triangular pyramid. The bond angle between the oxygen atom, carbon atom, and calcium ion is 129, implying that the molecule falls below the 120 predicted theoretically for equilateral triangles.

Formal Charge and Valence Electrons

To obtain an accurate Lewis structure of CaCO3, we must calculate the formal charge, which is the difference between the number of valence electrons in an isolated atom and the number assigned to it in a particular compound. The formal charge is calculated by subtracting the non-bonding electrons from half the bonding electrons in every atom of the molecule.

Lone Pairs and Hybridization

The oxygen atoms in CaCO3 molecules have two sets of lone pairs that help to stabilize the molecular structure by occupying regions of negative charge. Hybridization occurs when orbitals of different energies are mixed to create hybrid orbitals that have equal energies.

Sp2 hybrid orbitals cover the central carbon atom, whereas s orbitals from Ca ion fill the available orbital to support the stable configuration of the molecule.

Facts about CaCO3

One of the most important features of CaCO3 is its molar mass, which is 100.09 grams per mole. It appears as a white or colorless crystalline powder with no odor and a melting point of 1339 degrees Celsius.

Uses of CaCO3

CaCO3 is used in a variety of industries, from food to medicine and construction. It works as an antacid for people with acid-related problems in the digestive system and can also be consumed as a calcium supplement.

CaCO3 also serves as an ingredient in toothpaste, cosmetics, and baking powder. Solubility, Acidic/Basic/Neutral Character and Electrolytic Character

CaCO3 is a sparingly soluble salt that ionizes weakly to yield calcium and carbonate ions.

In water, the ions dissociate to produce a neutral or slightly basic solution since the carbonate ion is the conjugate base of the weak carbonic acid. CaCO3, when dissolved in water, is considered a weak electrolyte that conducts electricity poorly, implying that it dissociates less in the solution.

In conclusion, calcium carbonate and the Lewis structure of CaCO3 are fascinating to explore in science and most importantly, significant in various industries around the world. As we continue to study the molecule and its properties, we gain important knowledge that impacts society in a multitude of ways.

One of the striking features of calcium carbonate (CaCO3) is its behavior in various settings. This behavior can be explained by a few key factors, including its solubility in water, polar/non-polar character, basic character, and ionic vs.

covalent nature.

Solubility in Water

CaCO3 is generally considered poorly soluble in water. This is due to the electrostatic force of attraction between the ions in the salt and the polar water molecules.

In calcium carbonate, the Ca2+ ion carries a strong positive charge, while the CO32- ion has a strong negative charge. These charges give rise to a high lattice energy or force of attraction between these ions.

Lattice energy is the energy required to separate a molecule or salt into its constituent ions. As a result, it is relatively challenging to breakdown CaCO3 into its individual ions.

That’s why CaCO3 does not readily dissolve in water. Solubility product (Ksp) is a measure of the solubility of a salt and is used to calculate the maximum concentration of ions in a solution.

It is defined as the product of the ion concentrations raised to the power of their stoichiometric coefficients. For calcium carbonate, the Ksp can be calculated with the following equation:

Ksp = [Ca2+][CO32-]

The solubility product expression for this equilibrium shows that if one of the two ion concentrations decreases, the other ion concentration will increase as the product remains constant.

This equation explains why increasing the concentration of calcium ions in a solution containing CaCO3 will cause the salt to dissolve. Simply put, the calcium ions compete with the carbonate ions for a limited amount of space around the salt.

Polar/Non-Polar Character

The polarizing power of a cation or polar molecule plays a crucial role in the solubility of a salt in water. For instance, the polar nature of water molecules attracts cations and anions in ionic salts by virtue of electrostatic forces of attraction.

Water is considered a polar solvent due to its high dielectric constant, which reduces the strength of these attractive forces. In the case of CaCO3, the relationship between the polarizing properties of the ions and their solubility characteristics becomes more complex.

The carbonate ion (CO32-) has a negative charge, and the carbon atom is less electronegative than the oxygen atoms in the ion. This creates a slight dipole moment, contributing to the polar nature of the molecule.

The calcium ion (Ca2+) is comparatively small and strongly polarizing; thus, the ion-dipole interactions between carbonate ions and calcium ions are strong and increase the stability of CaCO3. This is an important reason why CaCO3 is only slightly soluble in water.

Basic Character

CaCO3 is an alkaline substance, which means it has basic tendencies. When added to an acidic solution, the calcium carbonate reacts to neutralize the acid and produce carbon dioxide (CO2) gas.

For example, when calcium carbonate reacts with hydrochloric acid (HCl), the following reaction takes place:

CaCO3 + HCl CaCl2 + CO2 + H2O

The production of carbon dioxide gas during the reaction causes the solution’s effervescence. This explains why calcium carbonate is used in several antacid formulations to treat stomach acidity.

Ionic vs Covalent Character

CaCO3 is an ionic compound, consisting of a metal cation (Ca2+) and non-metal anion (CO32-). An ionic bond refers to the bond formed by the electrostatic force of attraction between positively and negatively charged ions.

Since CaCO3 has a polar covalent bond between the carbon and oxygen atoms, while the Ca and CO32- ions form a strong ionic bond, it is classified as an ionic compound. The nature of a compound influences its properties and behavior, and the ionic vs.

covalent character of CaCO3 impacts its solubility, basic character, and stability.


In conclusion, calcium carbonates behavior can be attributed to various factors such as its solubility in water, polar/non-polar character, basic character, and ionic vs. covalent nature.

These properties, when correctly understood, can help in many fields from industrial processes to medical applications. Understanding how CaCO3 behaves helps us identify its significant impact on the world around us.

We hope this article helped you understand the exciting world of calcium carbonate better. Calcium carbonate (CaCO3) is a fascinating compound that displays unique behaviors influenced by factors such as solubility in water, polar/non-polar character, basic character, and ionic vs.

covalent nature. Its properties have significant impacts on several industries, and understanding its behavior enables us to identify the best application practices.

Calcium carbonate has implications in everything from food to construction industries, and its unique features are essential.


Q: What is calcium carbonate used for?

A: Calcium carbonate is used in various industries such as food, medicine, and construction, where it serves as an antacid, calcium supplement, and an ingredient in toothpaste, cosmetics, and baking powder. Q: Why isn’t calcium carbonate very soluble in water?

A: Calcium carbonate is a sparingly soluble salt due to the strong electrostatic force of attraction between the Ca and CO3 ions and the polar water molecules. Q: Is calcium carbonate an ionic or covalent compound?

A: Calcium carbonate is an ionic compound consisting of a metal cation (Ca2+) and non-metal anion (CO32-). Q: Why is calcium carbonate used as an antacid?

A: Calcium carbonate is used as an antacid because it is a basic substance that can neutralize acids present in the stomach. Q: What is the role of the polarizing power of calcium ions in solubility of calcium carbonate in water?

A: The polarizing power of calcium ions is crucial for the solubility of calcium carbonate in a polar solvent such as water. Calcium ions interact strongly with carbonate ions, which hinders their dissolution in water.

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