BackThe Chemical Level of Organization: Atoms and Elements in Human Physiology
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Atoms and Matter
Introduction to Atoms
Atoms are the fundamental units of matter, forming the basis for all chemical substances. Their unique arrangements and interactions determine the chemical characteristics that underlie physiological processes at the molecular and cellular levels.
Matter is composed of atoms.
Atoms combine to form chemicals with distinct properties.
Chemical properties influence physiological functions in living organisms.
Subatomic Particles
Atoms consist of three primary subatomic particles, each contributing to the atom's structure and behavior.
Proton: Positively charged, 1 mass unit.
Neutron: Neutral charge, 1 mass unit.
Electron: Negatively charged, very low mass.
Atomic Structure
Atomic Number and Mass Number
The identity and mass of an atom are determined by its atomic number and mass number.
Atomic number: Number of protons in the nucleus.
Mass number: Total number of protons and neutrons.
Nucleus and Electron Cloud
An atom is organized into a central nucleus and an electron cloud.
Nucleus: Contains protons and neutrons.
Electron cloud: Contains electrons, which occupy energy levels or shells around the nucleus.
Isotopes of Hydrogen
Hydrogen Atom Variants
Hydrogen exists in three isotopic forms, differing in the number of neutrons.
Hydrogen-1 (protium): 1 proton, 0 neutrons.
Hydrogen-2 (deuterium): 1 proton, 1 neutron.
Hydrogen-3 (tritium): 1 proton, 2 neutrons.
Additional info: Isotopes have identical chemical properties but may differ in stability and physical properties due to neutron number.
Principal Elements in the Human Body
Major Elements and Their Significance
The human body is composed primarily of a few key elements, each serving vital physiological roles.
Element | % of Total Body Weight | Significance |
|---|---|---|
Oxygen (O) | 65 | Component of water and other compounds; essential for respiration in gaseous form |
Carbon (C) | 18.6 | Found in all organic molecules |
Hydrogen (H) | 9.7 | Component of water and most other compounds in the body |
Additional info: These elements are fundamental to the structure and function of biomolecules such as carbohydrates, proteins, lipids, and nucleic acids.
Summary
Understanding the atomic structure and elemental composition of the human body is essential for grasping the chemical basis of physiological processes. Atoms, their subatomic particles, and the major elements form the foundation for the complex molecules and reactions that sustain life.
