Chapter 2: Chemical Principles

Introduction

Microbial chemistry is fundamental to understanding how microorganisms grow, function, and interact with their environment. Microbes use nutrients to build essential cellular components and release energy through chemical reactions. These processes are central to their survival and impact many aspects of human life, from food spoilage to disease and biotechnology.

• Microbial chemistry involves the transformation of nutrients into new substances, releasing energy.

• Examples include the souring of milk (fermentation by bacteria) and decomposition in nature.

• Understanding microbial chemistry is crucial for microbiologists to comprehend disease mechanisms, infection control, and the development of antibiotics and vaccines.

Section 2.1: The Structure of Atoms

Atoms: The Building Blocks of Matter

Atoms are the smallest units of matter that retain the properties of an element. They combine to form molecules, which are the basis of all living and non-living things. Chemistry is the study of these atoms and molecules.

• Atom: Consists of a nucleus (protons and neutrons) and electrons in shells around the nucleus.

• Proton (p+): Positively charged particle in the nucleus.

• Neutron (n0): Uncharged particle in the nucleus.

• Electron (e-): Negatively charged particle in electron shells.

• Atoms are electrically neutral: number of protons = number of electrons.

Elements and Atomic Number

Each element is defined by its atomic number, which is the number of protons in its nucleus. Elements have unique symbols and are essential for life.

• Element: A substance that cannot be broken down into simpler substances by chemical means.

• Atomic number: Number of protons in the nucleus.

• About 26 of the 92 natural elements are commonly found in living organisms.

Additional info: The table above lists key elements found in living organisms. Hydrogen, carbon, nitrogen, and oxygen are the most abundant.

Isotopes

Isotopes are variants of elements with the same number of protons but different numbers of neutrons. They are important in biological research and medical applications.

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

• Example: Oxygen has isotopes O-16, O-17, and O-18.

• Applications: Radioactive isotopes are used in sterilization and tracing biological processes.