BackThe Chemistry of Life: Chapter 2 Study Notes
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The Chemistry of Life
Introduction
The study of biology begins with understanding the chemical basis of life. Living organisms are composed of specific elements and compounds that interact to sustain life processes. This chapter explores the essential elements, atomic structure, and the foundational chemistry underlying biological systems.
Elements Essential to Life
Major and Trace Elements in the Human Body
Living organisms are primarily made up of a small number of elements, with a few present in trace amounts but still vital for biological functions.
Major Elements: Carbon (C), Oxygen (O), Nitrogen (N), Hydrogen (H), Phosphorus (P), Sulfur (S), Potassium (K), Sodium (Na), Calcium (Ca), Magnesium (Mg), Chlorine (Cl), Iron (Fe)
Trace Elements: Zinc (Zn), Manganese (Mn), Copper (Cu), Iodine (I), Selenium (Se), and others
Element | Approximate % of Body Mass |
|---|---|
Carbon | 50% |
Oxygen | 20% |
Nitrogen | 14% |
Hydrogen | 8% |
Phosphorus | 3% |
Sulfur | 1% |
Potassium | 1% |
Sodium | 1% |
Calcium | 0.5% |
Magnesium | 0.5% |
Chlorine | 0.5% |
Iron | 0.2% |
Trace metals | 0.3% |
Example: The human body contains about $4.00 worth of these elements in total.
Elements and Atoms
Definitions and Properties
All matter is composed of elements, which are substances with specific chemical properties that cannot be broken down by ordinary chemical reactions. Each element consists of atoms, the smallest unit that retains the properties of the element.
Element: A pure substance consisting of only one type of atom.
Atom: The smallest unit of an element, maintaining its chemical identity.
Examples: Carbon (C), Sodium (Na), Phosphorus (P)
Application: Elements such as carbon, sodium, and phosphorus are essential for biological molecules and cellular functions.
Atomic Structure
Subatomic Particles
Atoms are composed of three major subatomic particles, each with distinct properties:
Proton: Positively charged particle found in the nucleus; determines the atomic number and identity of the element.
Neutron: Neutral particle found in the nucleus; contributes to atomic mass and isotope formation.
Electron: Negatively charged particle orbiting the nucleus; involved in chemical bonding and reactions.
Particle | Charge | Location |
|---|---|---|
Proton | +1 | Nucleus |
Neutron | 0 | Nucleus |
Electron | -1 | Electron cloud/orbitals |
Example: The number of protons in the nucleus defines the element (e.g., carbon has 6 protons).
Summary
Understanding the chemical composition and atomic structure of living organisms is fundamental to biology. The major elements and their atomic properties set the stage for the complex chemistry that supports life.
