BackThe Chemical Context of Life: Atomic Structure and Elements
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The Chemical Context of Life: Atomic Structure
The Elements of Life
All living organisms are composed of matter, which is anything that occupies space and has mass. The study of the elements and their atomic structure is fundamental to understanding biological processes.
Matter: Anything that takes up space and has mass.
Elements: Pure substances that cannot be broken down into other substances by chemical reactions.
There are 92 naturally occurring elements, but only about 20–25% are essential for life (essential elements).
Major elements in living organisms: Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N)—these make up approximately 96% of living matter.
The remaining 4% consists mainly of calcium (Ca), phosphorus (P), potassium (K), and sulfur (S).
Trace elements are required in only minute quantities but are vital for proper biological function.
Table: Elements in the Human Body
Element | Symbol | Percentage of Body Mass (including water) |
|---|---|---|
Oxygen | O | 65.0% |
Carbon | C | 18.5% |
Hydrogen | H | 9.5% |
Nitrogen | N | 3.3% |
Calcium | Ca | 1.5% |
Phosphorus | P | 1.0% |
Potassium | K | 0.4% |
Sulfur | S | 0.3% |
Sodium | Na | 0.2% |
Chlorine | Cl | 0.2% |
Magnesium | Mg | 0.1% |
Trace elements (less than 0.01% of mass): Boron (B), chromium (Cr), cobalt (Co), copper (Cu), fluorine (F), iodine (I), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), silicon (Si), tin (Sn), vanadium (V), zinc (Zn).
Example: Iron (Fe) is a trace element essential for oxygen transport in blood.
Additional info: The distribution of elements in the human body reflects their roles in biological molecules and physiological processes. For example, calcium is crucial for bone structure, while potassium and sodium are vital for nerve function.
