Chemicals are substances with a distinct molecular composition that are produced through a chemical process. They can be found in various forms such as solids, liquids, and gases. Chemicals play a crucial role in our daily lives, from the food we eat to the products we use.
Types of Chemicals
Chemicals can be classified into several categories based on their composition and properties:
Elements: These are substances that cannot be broken down into simpler substances by chemical means. Examples include oxygen, carbon, and hydrogen.
Compounds: These are substances composed of two or more elements that are chemically combined in fixed proportions. Water (H2O) and carbon dioxide (CO2) are examples of compounds.
Mixtures: These are combinations of two or more substances that are not chemically combined. Mixtures can be homogeneous (uniform composition) or heterogeneous (non-uniform composition).
Chemical reactions occur when substances undergo a chemical change to form new substances with different properties. The reactants are the substances that undergo the change, while the products are the new substances formed.
From Molecules to Organisms: Structures and Processes
Students who demonstrate understanding can:
Construct an argument that plants and animals have internal and external structures that function to support survival, growth, behavior, and reproduction.