What happens to molecular structure during a chemical change?

During a chemical change, the molecular structure of substances is altered, forming new substances with different properties.

In a chemical change, also known as a chemical reaction, the atoms in the reactant molecules are rearranged to form new products. This process involves the breaking of bonds in the reactants and the formation of new bonds to create the products. The molecular structure of a substance is determined by how its atoms are arranged and bonded together. Therefore, when a chemical change occurs, the molecular structure of the substances involved is fundamentally altered.

For instance, consider the combustion of methane (CH4). In this reaction, methane reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). The molecular structure of methane, which consists of one carbon atom bonded to four hydrogen atoms, is changed. The bonds between the carbon and hydrogen atoms are broken, and new bonds are formed between the carbon and oxygen atoms and between the hydrogen and oxygen atoms. This results in the formation of carbon dioxide and water, each with their own unique molecular structures.

It's important to note that during a chemical change, the total number of each type of atom is conserved. This is known as the law of conservation of mass. In the combustion of methane example, the total number of carbon, hydrogen, and oxygen atoms remains the same before and after the reaction. However, the way these atoms are arranged and bonded together changes, leading to the formation of new substances with different properties.

In summary, a chemical change involves a fundamental alteration of the molecular structure of substances. This is achieved through the breaking and forming of chemical bonds, leading to the creation of new substances with different properties.