1. Atoms are the fundamental building blocks: The atomic theory states that all matter is composed of tiny, indivisible particles called atoms. These atoms are the smallest units of an element that can exist.
2. Atoms are rearranged, not destroyed: Chemical reactions involve the rearrangement of atoms, not their creation or destruction. When a substance undergoes a chemical change, the atoms within the molecules are simply rearranged to form new molecules.
3. The total number of atoms remains constant: During a chemical reaction, the total number of atoms of each element present at the beginning of the reaction remains the same at the end. This is because atoms are not created or destroyed in chemical reactions, only rearranged.
4. Mass is conserved: Since atoms have mass and are not destroyed, the total mass of the reactants before a chemical reaction must be equal to the total mass of the products after the reaction. This is why we observe the law of conservation of mass – matter is neither created nor destroyed, only transformed.
Example: Consider the burning of wood.
* Before burning: The wood contains carbon, hydrogen, and oxygen atoms.
* During burning: The wood reacts with oxygen in the air. The carbon, hydrogen, and oxygen atoms rearrange to form new molecules of carbon dioxide, water vapor, and ash.
* After burning: The total number of carbon, hydrogen, and oxygen atoms remains the same, even though the molecules have changed. The mass of the wood, oxygen, and ash will be equal to the original mass of the wood before it burned.
In summary: The atomic theory provides a microscopic explanation for the macroscopic observation that matter is conserved. The idea that matter is composed of atoms that cannot be created or destroyed explains why the total mass of a system remains constant, even when chemical reactions occur.
