Concept 2.1: Matter Consists of Chemical Elements in Pure Form and in Combinations Called Compounds

Introduction to Matter

Matter is the fundamental substance that makes up all organisms and objects in the universe. Understanding matter and its composition is essential for studying biology and the chemical processes that sustain life.

• Matter: Anything that takes up space and has mass.

• Organisms: All living things are composed of matter.

Elements and Compounds

All matter is composed of elements, which can combine to form compounds with unique properties. These combinations are central to the structure and function of biological molecules.

• Element: A substance that cannot be broken down into other substances by chemical reactions.

• Compound: A substance consisting of two or more different elements combined in a fixed ratio.

• Molecule: A combination of two or more atoms held together by chemical bonds. Molecules can be composed of the same or different elements.

• Properties of Compounds: Compounds have characteristics different from those of their constituent elements.

Example: Formation of a Compound

• Sodium (Na): A highly reactive metal.

• Chlorine (Cl): A poisonous greenish gas.

• Compound Formed: When sodium and chlorine combine, they form sodium chloride (NaCl), commonly known as table salt, which is safe to eat and essential for life.

Summary Table: Elements, Molecules, and Compounds

Additional info: In biology, only a small number of elements (such as carbon, hydrogen, oxygen, and nitrogen) make up the majority of living matter. The unique properties of compounds formed from these elements are critical for the structure and function of cells.