Metal carbonates are bases. These are the type of bases which can undergo reaction with acid to give a salt,water and carbon dioxide. Also in their aqueous solution, carbonate ion hydrolysed to carbonic acid and give hydroxide ion which is responsible for their basic character.

Metal carbonates or hydrogen carbonates such as limestone (CaCO3), the antacid Tums (CaCO3), and baking soda (NaHCO3) are common examples.

Introduction
Acids and bases are two important categories of chemical substances that play a significant role in various chemical reactions and processes. Acids are characterized by their ability to donate protons (H+) in a solution, while bases are known for their ability to accept protons. The concept of acids and bases is essential in understanding various chemical reactions and their effects on the environment and living organisms.

Acids and Bases
Acids and bases are commonly classified based on their chemical properties and behavior in aqueous solutions. Acids are substances that increase the concentration of H+ ions when dissolved in water, while bases increase the concentration of OH- ions.

pH Scale
The pH scale is a measure of the acidity or basicity of a solution. It ranges from 0 to 14, with 7 being considered neutral. Solutions with a pH less than 7 are considered acidic, while those with a pH greater than 7 are considered basic or alkaline.

Metal Carbonates
Metal carbonates are compounds that contain a metal cation (such as calcium, magnesium, or sodium) and a carbonate anion (CO3^2-). Examples of metal carbonates include calcium carbonate (CaCO3) and sodium carbonate (Na2CO3).

Basic Nature of Metal Carbonates
Metal carbonates are generally considered basic or alkaline in nature. When metal carbonates are dissolved in water, they release hydroxide ions (OH-) into the solution. These hydroxide ions make the solution basic.

The basic nature of metal carbonates is attributed to the presence of carbonate ions. Carbonate ions have the ability to accept protons, making them basic. When metal carbonates dissolve in water, carbonate ions react with water molecules to form hydroxide ions and bicarbonate ions. The hydroxide ions contribute to the basic nature of the solution.

Examples
- When calcium carbonate (CaCO3) reacts with water, it forms calcium hydroxide (Ca(OH)2) and carbon dioxide (CO2). The formation of calcium hydroxide makes the solution basic.
- Sodium carbonate (Na2CO3) dissociates in water to form sodium hydroxide (NaOH) and carbon dioxide (CO2). Sodium hydroxide is a strong base and contributes to the basic nature of the solution.

Conclusion
Metal carbonates are generally considered basic due to the presence of carbonate ions, which have the ability to accept protons and release hydroxide ions in solution. Understanding the basic nature of metal carbonates is important in various chemical reactions and processes, especially in the field of chemistry.