BackChapters 2-5: The Chemistry of Life – General Biology Study Notes
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The Chemistry of Life
Overview
Understanding the chemical basis of life is essential for studying biology. Chapters 2-5 cover foundational topics including atomic structure, water and its properties, carbon chemistry, and the structure and function of biological macromolecules. These concepts are critical for grasping how living organisms function at the molecular level.
The Chemical Context of Life
Atoms and Elements
All matter is composed of atoms, which are the basic units of matter. Elements are substances that cannot be broken down into simpler substances by chemical means. Life on Earth is based on a limited set of elements, with carbon, hydrogen, oxygen, and nitrogen being the most abundant in living organisms.
Atom: The smallest unit of an element, retaining its chemical properties.
Element: A pure substance consisting of only one type of atom.
Major elements in biology: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), and others.
Example: Water (H2O) is composed of hydrogen and oxygen atoms.
Atomic Structure
Atoms consist of three main subatomic particles: protons, neutrons, and electrons. The arrangement of these particles determines the atom's properties and behavior in chemical reactions.
Protons: Positively charged particles found in the nucleus.
Neutrons: Neutral particles found in the nucleus.
Electrons: Negatively charged particles orbiting the nucleus.
Atomic number: Number of protons in the nucleus; defines the element.
Mass number: Sum of protons and neutrons.
Electron shells: Electrons are arranged in energy levels (shells) around the nucleus.
Example: Carbon (C) has 6 protons, 6 neutrons, and 6 electrons.
Element | Atomic Number | Electron Configuration |
|---|---|---|
Li (Lithium) | 3 | 2, 1 |
Be (Beryllium) | 4 | 2, 2 |
B (Boron) | 5 | 2, 3 |
C (Carbon) | 6 | 2, 4 |
Na (Sodium) | 11 | 2, 8, 1 |
Mg (Magnesium) | 12 | 2, 8, 2 |
Al (Aluminum) | 13 | 2, 8, 3 |
Si (Silicon) | 14 | 2, 8, 4 |
Additional info: Electron configuration determines chemical reactivity and bonding behavior.
