CHAPTER 1: Chemistry, Matter, and Measurement

Introduction to Chemistry

• What is Chemistry: the study of the interactions of matter with other matter and energy.

• Central Science: Chemistry serves as a foundational science that relates to all other sciences regarding molecules.

• Everyday Examples: include substances like glass, metal alloys, treated water, plastics, and baking soda.

• Matter: defined as anything that has mass and occupies space.

  • Mass and Weight: crucial measurements in chemistry.

Classification of Matter

• Physical Property: characteristics describing matter as it exists (shape, mass, color, size, temperature).

• Chemical Property: how matter changes its structure/composition (examples: tarnishing of silver, digestion of food).

• Physical Change vs. Chemical Change:

  • Physical: breaking wood into pieces.

  • Chemical: burning wood changes its chemical composition.

• Substance: matter that has the same physical/chemical properties; elements cannot be broken down into simpler substances.

  • Approximately 118 elements exist, with about 80 being stable.

  • Examples of Elements: Gold (Au), Sulfur (S), Sodium (Na).

Compounds and Mixtures

• Compounds: made up of more than one element (e.g., O2, H2).

• Mixtures: combination of substances that can be either homogeneous or heterogeneous.

  • Homogeneous Mixtures: uniform in composition (e.g., Kool-Aid).

  • Heterogeneous Mixtures: not uniform (e.g., sand and water).

States of Matter and Measurements

• States of Matter:

  • Physical Properties of Water:

    • Gas (steam), Liquid (water), Solid (ice).

    • Shape and volume vary (gas), constant in liquid and solid.

• Measurements: consist of a number and a unit for expressing quantities.

Expressing Numbers

• Scientific Notation: system for expressing large or small numbers in the form of a coefficient multiplied by a base (10 raised to an exponent).

• Rules for Significant Figures (Sig Figs):

  • Non-zero digits: always significant.

  • Leading zeros: not significant.

  • Embedded zeros: always significant.

  • Trailing zeros: significant only if there’s a decimal present.

Operations with Significant Figures

• Multiplication and Division Rule: result carries the number of significant figures as the factor with the least number of sig figs.

• Addition and Subtraction Rule: result carries the same number of decimal places as the quantity with the least decimal places.

• Rounding Rules: rounds up if the dropped digit is 5 or more and down if less than 5.

The International System of Units (SI)

• SI: modern version of the metric system, including base and derived units.

• Volume: amount of space a substance occupies, typically measured in liters (L) and cubic centimeters (cm³).

• Unit Conversions: use conversion factors to switch between units (e.g., 1 L = 1000 mL).

Dimensional Analysis

• Dimensional Analysis Process:

  1. Determine units in the final answer.

  2. Select appropriate conversion factors.

  3. Solve the problem using the factors.

• Example: converting hours to minutes using conversion factors.

More Dimensional Analysis Examples

• Mass of an Electron: measures in kilograms (kg) and examples of conversions detailed.

• Mass and Weight: common units (grams for mass); weight influenced by gravity.

Volume and Density

• Volume: measure of space occupied by matter.

  • 1 mL = 1 cm³, practical measurements for liquids.

• Density (d): ratio of mass (m) to volume (v), with examples of calculations of density from mass and volume.

Temperature Measurement

• Temperature: measured in Celsius (°C) or Kelvin (K) with scales described.

• Use of thermometer or electronic probes.

• Body Temperature: normal range cited (98.6°F = 37°C), conditions described that lead to hyperthermia and hypothermia.

Calculating Percentages in Health

• Percentage: comparison of two sets of numbers, calculated by dividing part by whole and multiplying by 100.

• Child Dosage Calculation: examples for dosage adjustments based on weight.

Units and Dosing in Healthcare

• Use of SI in healthcare; familiarity with dosage calculations essential.

Reading Lab Reports

• Key information about values in reports; how to interpret normal limits and out-of-range results.

• Basics of moles and measurement units explained.

Calculating Dosage in Medication

• Calculate total medication dosage required based on body weight, dosage per weight, and number of doses per day.

Example Problems in Chemistry

1. Calculating Density

   • Problem: A substance has a mass of 20 grams and occupies a volume of 5 cm³. What is its density?

   • Solution: Density (d) = mass (m) / volume (v) = 20 g / 5 cm³ = 4 g/cm³.

2. Converting Units

   • Problem: Convert 3.5 liters to milliliters.

   • Solution: Use the conversion factor (1 L = 1000 mL).

   • Solution: 3.5 L × 1000 mL/L = 3500 mL.

3. Calculating Percentages

   • Problem: If a patient weighs 70 kg and needs a medication dosage of 2 mg/kg, how much medication is required?

   • Solution: Total dosage = weight × dosage per kg = 70 kg × 2 mg/kg = 140 mg.

4. Significant Figures in Calculations

   • Problem: Multiply 2.35 (3 sig figs) by 3.2 (2 sig figs).

   • Solution: 2.35 × 3.2 = 7.52, but reported as 7.5 (2 sig figs due to 3.2).

5. Temperature Conversion

   • Problem: Convert body temperature from Fahrenheit to Celsius.

   • Solution: Use the formula °C = (°F - 32) × 5/9.

   • If body temperature is 98.6°F, then °C = (98.6 - 32) × 5/9 ≈ 37°C.