BackChapter 2: Chemistry Comes Alive – Basic Chemistry for Anatomy & Physiology
Study Guide - Smart Notes
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Part 1—Basic Chemistry
2.1 Matter and Energy
Understanding the fundamental concepts of matter and energy is essential for grasping the chemical basis of life processes in Anatomy & Physiology.
Matter: Anything that has mass and occupies space. Matter can be seen, smelled, or felt, and its weight is mass plus the effects of gravity.
States of Matter:
Solid: Definite shape and volume
Liquid: Changeable shape; definite volume
Gas: Changeable shape and volume
Energy: The capacity to do work or put matter into motion. The greater the work done, the more energy is used up.
Forms of Energy:
Kinetic Energy: Energy in action
Potential Energy: Stored (inactive) energy
Energy can be transformed from potential to kinetic; stored energy can be released, resulting in action.
Major Energy Forms
Chemical Energy: Stored in bonds of chemical substances
Electrical Energy: Results from movement of charged particles
Mechanical Energy: Directly involved in moving matter
Radiant/Electromagnetic Energy: Travels in waves (e.g., heat, visible light, ultraviolet light, X-rays)
Energy Form Conversions
Energy may be converted from one form to another (e.g., electrical energy to light energy when turning on a lamp).
Energy conversion is inefficient; some energy is "lost" as heat, which can be partly unusable.
2.2 Atoms and Elements
Atoms and elements are the building blocks of matter, forming the basis for all chemical processes in the body.
Chemical Element: Substances that cannot be broken down into simpler substances by ordinary chemical methods.
Four elements make up 96% of body mass: carbon, oxygen, hydrogen, and nitrogen.
Periodic table lists all known elements; 118 elements are recognized, 92 occur in nature.
Table: Common Elements Composing the Human Body
Element | Symbol | Atomic Number | Approx. % Body Mass | Function |
|---|---|---|---|---|
Oxygen | O | 8 | 65.0 | Component of organic and inorganic molecules; essential for cellular respiration |
Carbon | C | 6 | 18.5 | Forms backbone of all organic molecules |
Hydrogen | H | 1 | 9.5 | Component of water and most organic molecules |
Nitrogen | N | 7 | 3.3 | Component of proteins and nucleic acids |
Additional info: Other elements such as calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, and trace elements are also present and play vital roles in physiological processes.
Atoms: Structure and Properties
Atoms are the unique building blocks for each element.
Smallest particles of an element with properties of that element.
Atomic symbol: One- or two-letter chemical shorthand (e.g., "O" for oxygen).
Subatomic Particles
Particle | Charge | Mass (amu) | Location |
|---|---|---|---|
Proton | +1 | 1 | Nucleus |
Neutron | 0 | 1 | Nucleus |
Electron | -1 | ~0 | Orbitals around nucleus |
Number of positive protons is balanced by number of negative electrons, so atoms are electrically neutral.
Protons and neutrons are found in the nucleus; electrons orbit around the nucleus.
Planetary Model: Simplified model with electrons in fixed circular paths.
Orbital Model: Depicts probable regions where electrons are most likely to be found.
Identifying Elements
Atomic Number: Number of protons in nucleus; written as subscript to left of atomic symbol (e.g., for hydrogen).
Mass Number: Total number of protons and neutrons in nucleus; written as superscript to left of atomic symbol (e.g., for lithium).
Isotopes: Structural variations of same element; same number of protons but differ in number of neutrons.
Atomic Weight: Average of mass numbers of all isotope forms of an atom.
Radioisotopes
Radioisotopes are isotopes that decompose to more stable forms, releasing energy (radioactivity).
Used for biological research and medicine (e.g., medical imaging, cancer treatment).
Some radioisotopes can damage living tissues; others are used to destroy localized cancers.
Example: Carbon-14 is a radioisotope used in radiometric dating and medical diagnostics.
Additional info: Understanding atomic structure and isotopes is crucial for interpreting physiological processes such as metabolism, cellular respiration, and diagnostic imaging.
