Chemistry in Biology: Key Vocabulary

Introduction

Chemistry forms the foundation of biological processes. Understanding these key terms is essential for grasping how molecules interact in living systems. This section provides definitions and explanations of fundamental chemistry vocabulary relevant to biology.

Atoms and Elements

• Atom: The smallest unit of an element that retains the properties of that element.

• Element: A substance that cannot be broken down into other substances by chemical means. Examples include carbon (C), hydrogen (H), and oxygen (O).

• Atomic Number: The number of protons in the nucleus of an atom, which determines the element.

• Atomic Mass: The total mass of an atom, approximately equal to the sum of protons and neutrons.

• Mass Number: The sum of the number of protons and neutrons in an atom's nucleus.

• Trace Element: An element required by an organism in only minute quantities (e.g., iron, iodine).

Subatomic Particles

• Proton: A positively charged subatomic particle found in the nucleus.

• Neutron: A subatomic particle with no charge, also located in the nucleus.

• Electron: A negatively charged subatomic particle that orbits the nucleus in electron shells.

• Nucleus: The central core of an atom, containing protons and neutrons.

• Electron Shell: The energy levels where electrons are found around the nucleus.

Isotopes and Radioactivity

• Isotope: Atoms of the same element with different numbers of neutrons.

• Radioactive Isotope: An isotope whose nucleus decays spontaneously, emitting radiation.

Chemical Bonds and Molecules

• Chemical Bond: The attraction between two atoms resulting from sharing or transferring electrons.

• Covalent Bond: A strong bond formed when two atoms share one or more pairs of electrons.

• Nonpolar Covalent Bond: A covalent bond in which electrons are shared equally between two atoms.

• Polar Covalent Bond: A covalent bond in which electrons are shared unequally, resulting in partial charges.

• Ionic Bond: A bond formed when one atom transfers electrons to another, creating oppositely charged ions.

• Hydrogen Bond: A weak bond between a hydrogen atom and an electronegative atom (such as oxygen or nitrogen).

• Molecule: Two or more atoms held together by covalent bonds.

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

• Ion: An atom or molecule with an electrical charge due to the loss or gain of electrons.

• Electronegativity: The tendency of an atom to attract electrons in a covalent bond.

Chemical Reactions

• Chemical Reaction: The process in which chemical bonds are broken and formed, rearranging atoms into new substances.

• Reactant: A starting substance in a chemical reaction.

• Product: A substance formed as a result of a chemical reaction.

Solutions and Acids/Bases

• Solution: A homogeneous mixture of two or more substances.

• Solvent: The dissolving agent in a solution (e.g., water).

• Solute: The substance that is dissolved in a solution.

• Aqueous Solution: A solution in which water is the solvent.

• Acid: A substance that increases the hydrogen ion (H+) concentration in a solution.

• Base: A substance that decreases the hydrogen ion concentration, often by accepting H+ or releasing OH-.

• Buffer: A substance that minimizes changes in pH by accepting or donating H+ ions.

• pH Scale: A scale (0-14) used to measure the acidity or basicity of a solution. Equation:

• Salt: A compound resulting from the neutralization reaction of an acid and a base.

• Ocean Acidification: The process by which CO2 dissolves in seawater, forming acids and lowering ocean pH.

Properties of Water

• Cohesion: The attraction between molecules of the same substance (e.g., water molecules sticking together).

• Adhesion: The attraction between molecules of different substances (e.g., water molecules sticking to glass).

• Surface Tension: A measure of how difficult it is to stretch or break the surface of a liquid due to cohesive forces.

• Evaporative Cooling: The reduction in temperature resulting from the evaporation of a liquid, which removes heat from the surface.

Energy and Temperature

• Heat: The total amount of kinetic energy due to molecular motion in a body of matter.

• Temperature: A measure of the average kinetic energy of the particles in a substance.

• Thermal Energy: The energy associated with the random movement of atoms and molecules.

Example Table: Types of Chemical Bonds

Summary

• Understanding these terms is crucial for studying biological molecules and processes.

• Many biological phenomena, such as enzyme function and cellular respiration, depend on chemical interactions described by these terms.