91Ó°ÊÓ

The Law of Conservation of Mass is a fundamental principle in chemistry. It states that during a chemical reaction, the total mass of the reactants—substances present before the reaction—equals the total mass of the products—the substances formed as a result of the reaction.
This concept was established in the late 18th century by the French chemist Antoine Lavoisier. He discovered that even when substances change form or combine to create other substances, no mass is lost or gained.
The principle essentially tells us that mass is neither created nor destroyed in a closed system. This is an important aspect of chemical reactions that allows scientists to predict the amounts of products that will result from a given set of reactants. In practice, if you start a reaction with 100 grams of reactants, you should end up with 100 grams of products, assuming no mass has escaped our system.

Atoms are the foundational building blocks of matter. According to John Dalton's atomic theory, each element is composed of its own unique type of atom.
This theory was revolutionary in the early 19th century as it provided a comprehensible model explaining the composition and behavior of matter at a microscopic level.
Dalton proposed that atoms of a single element are identical in mass and properties. Yet, they differ from atoms of other elements. He also suggested that atoms are indivisible and indestructible during chemical processes, meaning they do not transform into other types of atoms.
Therefore, when chemical reactions occur, atoms do not vanish magically or change into different atoms. Instead, they switch partners and arrange themselves in new ways to create different substances. Understanding that atoms remain consistent before and after reactions is crucial for grasping more complex chemical concepts.

Chemical reactions involve the rearrangement of atoms to create new substances. This process can be seen as a transformation where existing bonds between atoms are broken, and new bonds are formed.
The key idea is that the initial atoms present in the reactants merely rearrange to form the products. This explains why the mass remains conserved, as emphasized by Dalton's theory and the Law of Conservation of Mass.
In a reaction, no atoms are physically lost; they are merely redistributed. For example, when hydrogen gas and oxygen gas react to form water, the atoms of hydrogen and oxygen rearrange, but no atoms disappear and no new ones appear.
In essence, chemical reactions are like reorganizing a group of friends into different teams. The number of participants remains the same despite how they are grouped. This aspect is fundamental in predicting reaction outcomes and calculating the quantities needed for chemical reactions.