Basic Chemistry for Health Sciences
Understand the chemical principles that govern biological processes, from atomic structure and bonding to pH, solutions, and the chemistry of life.
Atomic Structure & Chemical Bonds
Building blocks of all matter
All matter consists of atoms, and the way atoms interact determines the properties of every substance in the body. Three types of chemical bonds are essential to understand:
Types of Chemical Bonds
Why Bond Type Matters in Healthcare
Ionic bonds create electrolytes that dissociate in body fluids, essential for electrical signaling. Covalent bonds create the stable molecules of life. Hydrogen bonds maintain the 3D shapes of proteins and DNA. When a fever denatures enzymes, it's disrupting hydrogen bonds that maintain protein folding.
Ions, Electrolytes & Water
The chemistry of body fluids
When ionic compounds dissolve in water, they dissociate into charged particles. These electrolytes are responsible for nerve impulse transmission, muscle contraction, fluid balance, and pH regulation.
Key Cations (+)
Na⁺, primary extracellular cation, drives fluid volume. K⁺, primary intracellular cation, critical for cardiac and nerve function. Ca²⁺, muscle contraction, bone structure, clotting. Mg²⁺, enzyme cofactor, neuromuscular function.
Key Anions (−)
Cl⁻, follows sodium, maintains osmolarity. HCO₃⁻, bicarbonate, the body's primary pH buffer. HPO₄²⁻, phosphate, energy metabolism (ATP), bone. These balance the cations to maintain electrical neutrality.
Water as a Solvent
Water is a polar molecule, the oxygen end is slightly negative, the hydrogen end slightly positive. This polarity allows water to dissolve ionic and polar substances (hydrophilic), making it the universal solvent of the body. Non-polar substances (lipids) do not dissolve in water (hydrophobic), this is why cell membranes, made of phospholipids, form barriers in an aqueous environment.
Acids, Bases & pH
The hydrogen ion concentration scale
The pH scale is fundamental to understanding how the body maintains the narrow range (7.35–7.45) required for normal enzyme function and cellular processes.
The pH Scale
Acids
Substances that release H⁺ ions in solution. Strong acids (HCl) dissociate completely. Weak acids (carbonic acid, H₂CO₃) dissociate partially and are important in buffering systems.
Bases
Substances that accept H⁺ ions or release OH⁻ ions. Bicarbonate (HCO₃⁻) is the body's primary base. It neutralizes excess H⁺ by combining to form carbonic acid, which is then expelled as CO₂ by the lungs.
Buffer Systems
A buffer resists changes in pH by absorbing excess H⁺ or releasing H⁺ as needed. The bicarbonate buffer system is the most important: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. The lungs regulate CO₂ (acid side) and the kidneys regulate HCO₃⁻ (base side). This dual regulation is why respiratory and renal function both affect pH.
Solutions & Concentrations
How substances are measured in clinical practice
In healthcare, solutions are described by their concentration. Understanding concentrations is critical for medication preparation, IV fluid therapy, and lab value interpretation.
Concentration Units
mg/mL, milligrams of drug per milliliter of solution (most common in medication dosing). %, grams of solute per 100 mL of solution (0.9% NaCl = 0.9 g NaCl per 100 mL = 9 g/L). mEq/L, milliequivalents per liter (used for electrolytes, accounts for ionic charge). mmol/L, millimoles per liter (used for lab values like glucose in some countries).
Dilution Reasoning
When you dilute a solution, the amount of solute stays the same but the volume increases. C₁V₁ = C₂V₂. If you have 10 mL of a 10 mg/mL solution and add 90 mL of diluent, you now have 100 mL of a 1 mg/mL solution. The total drug amount (100 mg) hasn't changed.
Match the Chemistry Concept
Terms
Definitions
Chemistry Foundations Quiz
1/20What type of bond holds NaCl together in its solid crystal form?
Pre-nursing comprehensive review
1/20Which organelle contains its own DNA and is inherited exclusively from the mother?