The Chemistry of Microbiology: Structured Study Notes Ch2 - 1

The Chemistry of Microbiology

Atoms and Atomic Structure

The foundation of chemistry in microbiology begins with understanding atoms, the smallest units of matter. Atoms are composed of subatomic particles: protons, neutrons, and electrons. The arrangement and behavior of these particles determine the properties of elements and their interactions.

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

• Atoms: Smallest chemical units of matter.

• Atomic Structure:

  • Electrons: Negatively charged particles circling the nucleus.

  • Nucleus: Contains protons (positive) and neutrons (neutral).

Elements, Atomic Number, and Atomic Mass

Elements are defined by their atomic number, which is the number of protons in the nucleus. Atomic mass is the sum of protons, neutrons, and electrons, though electrons contribute minimally to mass.

• Element: Substance composed of a single type of atom.

• Atomic Number: Number of protons in the nucleus.

• Atomic Mass: Sum of masses of protons, neutrons, and electrons.

Common Elements of Life

Biological systems rely on a variety of elements, each with specific roles in cellular processes.

Element	Symbol	Atomic Number	Biological Significance
Hydrogen	H	1	Component of organic molecules and water; H+ released by acids
Carbon	C	6	Backbone of organic molecules
Nitrogen	N	7	Component of amino acids, proteins, and nucleic acids
Oxygen	O	8	Component of many organic molecules and water; necessary for aerobic metabolism
Phosphorus	P	15	Component of nucleic acids and ATP
Sulfur	S	16	Component of proteins
Iron	Fe	26	Component of energy-transferring proteins; transports oxygen in blood
Zinc	Zn	30	Component of some enzymes
Iodine	I	53	Component of many brown and red algae

Isotopes

Isotopes are atoms of the same element with different numbers of neutrons. Some isotopes are stable, while others are radioactive and release energy during decay.

• Stable Isotopes: Do not change over time.

• Radioactive Isotopes: Unstable, release energy during radioactive decay.

Electron Configuration and Valence

Electrons occupy shells around the nucleus. The outermost shell, containing valence electrons, determines an atom's chemical reactivity and bonding behavior.

• Valence Electrons: Electrons in the outermost shell; interact with other atoms.

• Electron Shells: Levels where electrons reside; filled shells confer stability.

Chemical Bonds

Chemical bonds form when atoms share or transfer valence electrons. The type of bond affects the properties of molecules and compounds.

• Covalent Bonds: Sharing of electron pairs between atoms.

  • Nonpolar Covalent: Electrons shared equally; no charge separation.

  • Polar Covalent: Electrons shared unequally; partial charges develop.

• Ionic Bonds: Electrons transferred from one atom to another, forming charged ions (cations and anions) that attract each other.

• Hydrogen Bonds: Weak electrical attraction between partially charged hydrogen and other atoms; important for stabilizing large molecules.

Comparison of Chemical Bonds

Type of Bond	Description	Relative Strength
Nonpolar Covalent	Electrons shared equally	Strong
Polar Covalent	Electrons shared unequally	Strong
Ionic	Electrons transferred; ions attract	Weaker than covalent in aqueous environments
Hydrogen	Partial positive charges on hydrogen attracted to negative charges	Weaker than ionic

Chemical Reactions

Chemical reactions involve the making or breaking of chemical bonds, transforming reactants into products. Biochemistry studies these reactions in living organisms.

• Reactants: Starting substances in a reaction.

• Products: Substances formed as a result of a reaction.

• Biochemistry: The study of chemical reactions in living things.

Additional info:

• Understanding atomic structure and chemical bonding is essential for grasping microbial metabolism, genetics, and cellular processes.

• Knowledge of elements and their roles in biological systems underpins topics such as microbial nutrition, growth, and metabolism.