Chemistry Basics: Matter, Measurement, and the Foundations of GOB Chemistry

Chemistry in Health Sciences

Importance of Chemistry for Nursing and Allied Health

Chemistry is fundamental for understanding the molecular basis of physiological processes, pharmacology, and patient care. It explains how molecules interact in the human body, the mechanisms of drug action, and the importance of nutrition and metabolism.

• Physiology and Pathophysiology: Chemistry helps explain cellular processes, disease mechanisms, and treatment strategies.

• Pharmacology: Understanding chemical reactions is essential for medication administration and monitoring.

• Nutrition: Chemistry clarifies why certain foods and vitamins are necessary for health.

• Examples: Explains cellular respiration, protein synthesis, blood types, and metabolic pathways.

Classification of Matter

Types of Matter

Matter is anything that occupies space and has mass. It can be classified as pure substances or mixtures.

• Pure Substances: Have a fixed composition and distinct properties. They are further classified as:

  • Elements: Simplest form of matter, made of only one type of atom (e.g., gold, oxygen).

  • Compounds: Substances composed of two or more elements chemically combined in fixed ratios (e.g., water, NaCl).

• Mixtures: Physical combinations of two or more substances. They can be separated by physical means and are classified as:

  • Homogeneous Mixtures (Solutions): Uniform composition throughout (e.g., air, vodka).

  • Heterogeneous Mixtures: Non-uniform composition (e.g., sand in water, salad).

Atomic Structure

Atoms and the Bohr Model

Atoms are the basic units of matter, consisting of a nucleus (protons and neutrons) and electrons in defined energy levels or shells.

• Protons: Positively charged particles in the nucleus.

• Neutrons: Neutral particles in the nucleus.

• Electrons: Negatively charged particles orbiting the nucleus in shells.

• Bohr Model: Electrons occupy specific shells (K, L, M, etc.), with each shell having a maximum number of electrons.

Octet Rule: Atoms are most stable when they have eight electrons in their outermost shell (except for the first shell, which is full with two electrons).

Electron Configuration Principles

• Aufbau Principle: Electrons fill the lowest energy orbitals first.

• Pauli Exclusion Principle: No more than two electrons can occupy the same orbital.

• Hund's Rule: Electrons fill degenerate orbitals singly before pairing up.

The Periodic Table

Organization and Classification

The periodic table arranges elements by increasing atomic number and groups elements with similar chemical properties.

• Groups (Columns): Elements with similar properties; labeled 1-18 (IUPAC) or with A/B notation.

• Periods (Rows): Horizontal rows numbered 1-7.

• Metals, Nonmetals, Metalloids: Separated by a staircase line; metalloids border this line (except Al).

Essential Elements for Life

• Macronutrients: Needed in >100 mg/day (e.g., Na, Mg, K, Ca, Cl).

• Micronutrients: Needed in <100 mg/day (e.g., I, F, Fe, Zn, Se).

Chemical Formulas and Compounds

Chemical Formulas

Chemical formulas indicate the elements present in a compound and the number of atoms of each element.

• Example: $\mathrm{H_2O}$ (2 hydrogen, 1 oxygen); $\mathrm{NaCl}$ (1 sodium, 1 chlorine).

Physical and Chemical Changes

Physical Changes

Physical changes alter the form or appearance of matter without changing its identity (e.g., melting, boiling, dissolving).

Chemical Changes

Chemical changes result in the formation of new substances with different properties; these are called chemical reactions.

• Examples: Burning, digestion, rusting, baking, metabolic reactions.

Chemical Equations and Balancing

Writing and Balancing Chemical Equations

Chemical equations represent chemical reactions, showing reactants and products. Equations must be balanced to obey the law of conservation of mass.

• General Form: Reactants $\rightarrow$ Products

• States: (s) solid, (l) liquid, (g) gas, (aq) aqueous

• Balancing Steps:

  1. Examine the equation for balance.

  2. Balance one element at a time using coefficients.

  3. Check that all elements are balanced with the smallest whole-number coefficients.

Measurement and Units

SI Units and Metric System

The SI (International System of Units) is the standard for scientific measurement.

• Mass: kilogram (kg)

• Volume: liter (L)

• Length: meter (m)

• Prefixes: Modify units by powers of 10 (e.g., milli-, centi-, kilo-)

Unit Conversions and Dimensional Analysis

• Use conversion factors to change from one unit to another.

• Set up problems so units cancel, leaving the desired unit.

• Example: $1\,\mathrm{dL} = 0.1\,\mathrm{L}$

Significant Figures

Significant figures reflect the precision of a measurement.

• All nonzero digits are significant.

• Zeros are significant only in certain positions (e.g., trailing zeros with a decimal point).

• Exact numbers (from definitions or counting) have infinite significant figures.

Rules for Calculations

• Addition/Subtraction: Result has the same number of decimal places as the least precise measurement.

• Multiplication/Division: Result has the same number of significant digits as the measurement with the fewest significant digits.

Scientific Notation

Scientific notation expresses numbers as $C \times 10^n$, where $1 \leq C < 10$ and $n$ is an integer.

• Example: $3.00 \times 10^2$ for 300; $6.6 \times 10^{-4}$ for 0.00066

Percent Calculations

• Percent (%) = $\frac{\text{part}}{\text{whole}} \times 100$

• Used to compare quantities and in health/nutrition labeling.

Properties of Matter

Mass vs. Weight

• Mass: Amount of matter in an object (measured in grams or kilograms).

• Weight: Force of gravity on an object; varies with location.

Volume

• Volume is the space occupied by matter (measured in liters, milliliters, or cubic centimeters).

• 1 mL = 1 cm3 (cc)

Density and Specific Gravity

• Density (d): $d = \frac{m}{V}$, where $m$ is mass and $V$ is volume.

• Density of water at 4°C is 1.00 g/mL.

• Specific Gravity: Ratio of the density of a substance to the density of water (unitless).

• Measured with a refractometer in clinical settings.

Temperature Scales

• Celsius (°C): Used in science and most countries.

• Fahrenheit (°F): Used in the United States.

• Kelvin (K): SI unit for temperature; $K = °C + 273$

• Conversions:

  • $°C = (°F - 32) \times \frac{5}{9}$

  • $°F = (°C \times \frac{9}{5}) + 32$

Heat and Specific Heat

• Heat: Kinetic energy transferred from a warmer to a cooler object.

• Specific Heat (SH): $\text{SH} = \frac{\text{heat}}{\text{mass} \times \Delta T}$

• Water has a high specific heat; metals have low specific heat.

Energy

• Energy: Capacity to do work or supply heat.

• Potential Energy: Stored energy.

• Kinetic Energy: Energy of motion.

• Law of Conservation of Energy: Energy is neither created nor destroyed.

• Units: Joule (J), calorie (cal); $1\,\text{cal} = 4.184\,\text{J}$; $1\,\text{Calorie (Cal)} = 1000\,\text{cal}$

States of Matter

Solid, Liquid, Gas

• Solid: Definite shape and volume; particles tightly packed.

• Liquid: Definite volume, indefinite shape; particles less orderly, move freely.

• Gas: No definite shape or volume; particles far apart, move rapidly.

Comparison Table:

Property	Solid	Liquid	Gas
Shape	Definite	Indefinite	Indefinite
Volume	Definite	Definite	Indefinite
Particle Arrangement	Orderly, tightly packed	Less orderly, close	Random, far apart
Compressibility	Very low	Low	High
Energy	Lowest	Intermediate	Highest

Accuracy and Precision in Measurement

• Accuracy: Closeness to the true value.

• Precision: Reproducibility of measurements.

• Best practice: Take multiple measurements and average them.

Measurement in Health and Clinical Contexts

Units and Dosing

• SI/metric units are standard, but U.S. customary units are also used.

• Common conversions: 1 dL = 100 mL; 1 kg = 2.2 lb.

• Dosages often calculated per body weight (mg/kg).

• Drop factor (gtt/mL) used for IV medication delivery.

Percent in Health

• Percent Active Ingredient: Used in medication formulation.

• Percent of Adult Dose: Pediatric doses are a percentage of adult doses.

• Percent Daily Value (%DV): Used in nutrition labeling.

Sample Calculations and Applications

• Density Calculation: $d = \frac{m}{V}$

• Specific Heat Calculation: $\text{SH} = \frac{\text{heat}}{\text{mass} \times \Delta T}$

• Percent Calculation: $\% = \frac{\text{part}}{\text{whole}} \times 100$

• Dosage Calculation: $\text{Dose} = \text{body weight (kg)} \times \text{dose per kg}$

Additional info: Some content inferred and expanded for clarity and completeness, including definitions, examples, and formulas.