Chapter 1: Chemistry Basics—Matter and Measurement (GOB Chemistry Study Notes)

Importance of Chemistry

Chemistry as the Central Science

Chemistry is often called the central science because it connects and influences many other scientific disciplines and aspects of daily life. Understanding chemistry is essential for fields such as medicine, nursing, engineering, and environmental science.

• Chemistry in Everyday Life: Chemistry is involved in the production and use of food, cleaners, energy, drugs, metals, textiles, remediation, cosmetics, paper, and healthcare.

• Applications: Chemistry helps explain processes such as drug formulation, energy production, environmental cleanup, and the development of new materials.

• Relevance to Health Professions: Knowledge of chemistry is crucial for safe medication administration, understanding biological processes, and preventing errors in healthcare settings.

Classifying Matter: Pure Substance or Mixture

Types of Matter

Matter is anything that occupies space and has mass. It can be classified into two main categories: pure substances and mixtures.

• Pure Substances: Matter with a fixed composition. Can be either elements or compounds.

• Mixtures: Combinations of two or more substances. Can be homogeneous (uniform composition) or heterogeneous (non-uniform composition).

Definitions and Examples

• Element: The simplest type of pure substance, made up of only one kind of atom. Example: Oxygen (O2).

• Compound: A pure substance composed of two or more elements chemically bonded in fixed ratios. Example: Water (H2O).

• Homogeneous Mixture: Mixture with uniform composition throughout. Example: Salt water.

• Heterogeneous Mixture: Mixture with non-uniform composition. Example: Oil and water.

Elements, Compounds, and the Periodic Table

Organization of the Periodic Table

The periodic table is a systematic arrangement of all known elements. Each element is represented by a chemical symbol, often derived from its English or Latin name.

• Groups: Vertical columns with similar chemical properties. Numbered 1–18 (IUPAC system).

• Periods: Horizontal rows numbered 1–7.

• Metals, Nonmetals, and Metalloids: Metals are found to the left of the staircase line, nonmetals to the right, and metalloids border the line (except aluminum).

Essential Elements for Life

• Macronutrients: Needed in quantities >100 mg/day (e.g., sodium, potassium, calcium).

• Micronutrients: Needed in quantities <100 mg/day (e.g., iron, zinc, iodine).

Chemical Formulas

Chemical formulas indicate the types and numbers of atoms in a compound.

• Example: Water: $H_2O$ (2 hydrogen atoms, 1 oxygen atom)

• Example: Sodium chloride: $NaCl$ (1 sodium atom, 1 chlorine atom)

How Matter Changes

Physical and Chemical Changes

Matter can undergo changes that are classified as either physical or chemical.

• Physical Change: Alters the form or appearance of matter but not its identity. Example: Melting ice.

• Chemical Change: Alters the chemical identity of a substance; a chemical reaction occurs. Example: Burning wood.

Chemical Equations and Conservation of Mass

• Chemical Equation: Represents a chemical reaction using symbols and formulas. Example: $C + O_2 ightarrow CO_2$

• Balancing Equations: The number of atoms of each element must be the same on both sides of the equation, illustrating the law of conservation of mass.

• Coefficients: Numbers placed before formulas to balance equations.

Math Counts

Significant Figures

Significant figures reflect the precision of a measurement.

• Rules: All nonzero digits are significant; zeros are significant depending on their position.

• Exact Numbers: Defined values and counted items have infinite significant figures.

Scientific Notation

Scientific notation expresses numbers as a coefficient times a power of ten.

• General Form: $C \times 10^n$

• Example: $8.564 \times 10^8$

Calculations and Rounding

• Addition/Subtraction: Match the least number of decimal places.

• Multiplication/Division: Match the least number of significant digits.

• Rounding: If the digit to be dropped is 5 or greater, increase the last retained digit by 1.

Metric System and SI Units

The metric system is used for scientific measurements.

• Mass: Kilogram (kg)

• Volume: Liter (L)

• Length: Meter (m)

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

Unit Conversions and Dimensional Analysis

• Conversion Factor: A ratio used to convert from one unit to another.

• Dimensional Analysis Steps:

  1. Determine desired units.

  2. Establish given information.

  3. Choose appropriate conversion factors.

  4. Solve the problem.

Percent Calculations

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

• Applications: Used in health, nutrition, and dosing calculations.

Matter: The “Stuff” of Chemistry

Mass and Volume

• Mass: Amount of material in an object, measured in grams (g).

• Volume: Space occupied by matter, measured in liters (L) or milliliters (mL).

• Clinical Units: Cubic centimeter (cc or cm3) is equivalent to 1 mL.

Density and Specific Gravity

• Density (d): Comparison of mass to volume. $d = \frac{m}{v}$

• Specific Gravity: Ratio of the density of a sample to the density of water. $\text{Specific gravity} = \frac{\text{density of sample}}{\text{density of water}}$

• Units: Density is in g/mL; specific gravity is unitless.

Temperature Scales

• Fahrenheit (°F): Common in the U.S.

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

• Kelvin (K): SI unit for temperature.

• Conversions:

  • $K = °C + 273$

  • $°C = \frac{(°F - 32)}{1.8}$

  • $°F = (°C \times 1.8) + 32$

Energy and Specific Heat

• Energy: Capacity to do work or supply heat. SI unit is joule (J); calorie (cal) is also used.

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

• Specific Heat (SH): Amount of heat needed to raise the temperature of 1 g of a substance by 1°C. $\text{Specific heat} = \frac{\text{heat}}{\text{mass} \times \Delta T}$

States of Matter

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

• Liquid: Definite volume, takes shape of container; particles move more freely.

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

State	Shape	Volume	Particle Arrangement
Solid	Definite	Definite	Orderly, tightly packed
Liquid	Indefinite (container)	Definite	Less orderly, move freely
Gas	Indefinite	Indefinite	Far apart, random motion

Measuring Matter

Accuracy and Precision

• Accuracy: How close a measurement is to the true value.

• Precision: How close repeated measurements are to each other.

• Best Practice: Take multiple measurements and average them.

Units in Health and Dosage Calculations

• SI/Metric Units: Used for scientific and clinical measurements.

• U.S. Customary Units: May be encountered in healthcare settings.

• Conversion Factors: Used to convert between units (e.g., 1 lb = 0.454 kg).

• Dosage Calculations: Use conversion factors and percent calculations to determine correct medication doses.

Unit	SI/Metric Equivalent	U.S. Customary Equivalent
Mass	gram (g)	ounce (oz), pound (lb)
Volume	liter (L), milliliter (mL)	teaspoon (tsp), tablespoon (tbsp), cup
Length	meter (m)	inch (in), foot (ft)

Percent in Health Applications

• Percent Active Ingredient: Used to determine the concentration of a drug in a tablet.

• Percent of Adult Dose: Used to adjust medication for children.

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

Additional info: These notes are based on textbook slides and introductory content for a GOB Chemistry course, suitable for college students in health and science majors.