1. Breaking Existing Bonds:
* Reactants: The starting materials of a chemical reaction have their own set of chemical bonds holding their atoms together.
* Energy Input: Energy is required to break these existing bonds. This energy can come from various sources like heat, light, or electricity.
2. Rearranging Atoms:
* Collision and Activation Energy: The reactants collide with enough energy (activation energy) to overcome the bond strength and break apart.
* Formation of Intermediate Species: Atoms and fragments may exist briefly in unstable, intermediate states during the reaction.
3. Forming New Bonds:
* Attraction: The atoms and fragments from the broken bonds rearrange, forming new attractions (bonds) based on their electronegativity and other factors.
* Product Formation: This results in the formation of new, more stable molecules called products.
Key Concepts:
* Energy Conservation: Chemical reactions obey the law of conservation of energy. The total energy of the system (including the reactants and products) remains constant.
* Exothermic vs. Endothermic: Reactions can either release energy (exothermic, like burning fuel) or require energy input (endothermic, like photosynthesis).
Example:
Consider the reaction between sodium (Na) and chlorine (Cl) to form sodium chloride (NaCl):
* Reactants: Na has a single outer electron, Cl has 7.
* Bond Breaking: The bond holding the chlorine atoms together breaks.
* Rearrangement: The sodium atom loses its outer electron to become a positively charged ion (Na+). The chlorine atom gains the electron to become a negatively charged ion (Cl-).
* New Bond Formation: The opposite charges of the ions attract, forming an ionic bond to create the stable compound NaCl (table salt).
In short, chemical reactions involve the breaking of existing bonds between atoms in reactants and the formation of new bonds to create different compounds (products).
