Summary
Highlights
Scientists represent chemical reactions using chemical equations. Reactants' chemical formulas are on the left, and products' on the right. Crucially, products must contain the same amount and type of elements as the reactants, in accordance with the law of conservation of matter, which states matter cannot be created or destroyed.
A chemical reaction is a process where substances interact to form different substances by breaking, forming, or rearranging chemical bonds. These substances can be ionic or covalent compounds, atoms, ions, or molecules of elements.
Photosynthesis is an example of a chemical reaction where plants use the sun's energy to combine carbon dioxide and water to produce glucose (a sugar) and oxygen. In this reaction, carbon dioxide and water are reactants, while glucose and oxygen are products.
To satisfy the law of conservation of matter, chemical equations must be balanced, meaning the number of atoms of each element in the reactants must equal those in the products. Coefficients, numbers placed in front of chemical formulas, indicate the number of molecules of each reactant and product, ensuring the equation is balanced.
In review, chemical reactions involve breaking and reforming chemical bonds to create new substances. Reactants are the starting substances, and products are the new substances formed. Chemical equations express these reactions, and they must be balanced to adhere to the law of conservation of matter.