Fundamentals of General Chemistry

1.1 Chemistry: The Central Science
  • Chemistry Defined: The study of the nature, properties, and transformations of matter.
  • Matter: Anything that has mass and occupies space (visible and tangible).
    • Examples: Solids, liquids, gases.
  • Scientific Method: Process of observation, hypothesis, experimentation to expand knowledge.
  • Properties of Matter:
    • Useful for identifying substances.
    • Types:
    • Size
    • Color
    • Temperature
    • Chemical Composition
    • Chemical Reactivity
  • Types of Changes:
    • Physical Change: No change in chemical makeup.
    • Example: Sugar dissolving in water.
    • Chemical Change: Change in chemical composition, forming new substances.
    • Example: Heating sugar to make caramel.
1.2 States of Matter
  • Three Forms of Matter:
    • Solid: Definite shape and volume.
    • Liquid: Definite volume, takes shape of container.
    • Gas: No definite volume or shape.
  • State Change: Transition between different states (e.g., liquid to gas).
  • Example: Formaldehyde state at room temperature (25 °C) is gas (bp = -19.5 °C).
1.3 Classification of Matter
  • Types of Matter:
    • Pure Substance: Uniform composition.
    • Mixture: Blend of two or more substances, each retaining identity.
    • Homogeneous Mixture: Uniform throughout (e.g., salt water).
    • Heterogeneous Mixture: Non-uniform (e.g., chocolate chip cookies).
  • Pure Substances:
    • Elements: Cannot be chemically broken down (e.g., gold).
    • Compounds: Can be broken down chemically (e.g., water).
1.4 Chemical Elements and Symbols
  • Elements:
    • 118 known; 91 found in nature.
    • Symbols are usually one or two letters (first is uppercase, second is lowercase, if any).
  • Naming Examples:
    • O = Oxygen, Au = Gold (from Latin "Aurum"), Na = Sodium (from Latin "Natrium").
  • Chemical Formula: Composed of element symbols and subscripts indicating the number of atoms.
1.5 Chemical Reactions: Examples of Chemical Change
  • Chemical Reaction: Process altering identity and composition of substances.
    • Reactants: Starting materials.
    • Products: Substances formed.
  • Example: Decomposition of water into hydrogen and oxygen.
    • Reaction: 2H₂O (l) → 2H₂ (g) + O₂ (g)
1.6 Physical Quantities: Units and Scientific Notation
  • Physical Quantities: Generated from measurements (mass, volume, temperature).
  • SI Units:
    • Mass: kg; Length: m; Volume: m³; Temperature: K.
  • Derived Units: Density (g/cm³).
  • Scientific Notation: Expressed as a number between 1 and 10 multiplied by $10^n$.
    • For example, $215 = 2.15 × 10^2$.
1.7 Measuring Mass, Length, and Volume
  • Mass vs. Weight:
    • Mass: Amount of matter in an object.
    • Weight: Gravitational force on an object.
  • Length: Meter is standard unit; 1 m = 39.37 inches.
  • Volume: Commonly measured in liters in chemistry.
1.8 Measurement and Significant Figures
  • Significant Figures: Reflects precision of measurements, containing all known digits plus one estimated digit.
  • Rules:
    • Non-zero numbers are significant.
    • Leading zeros are not significant.
    • Trailing zeros after decimal are significant.
    • Trailing zeros before an implied decimal may be significant potentially.
1.9 Rounding Off Numbers
  • Rounding Rules:
    • Multiplication/Division: Answer can't have more significant figures than the original numbers.
    • Addition/Subtraction: Answer can't have more decimal places than the original numbers.
1.10 Problem Solving: Unit Conversions and Estimating Answers
  • Factor-Label Method: Helps convert between units by canceling undesirable units.
  • Steps in Unit Conversion:
    • Identify provided info and needed answer.
    • ESTIMATE to check answer reasonability after calculation.
1.11 Temperature, Heat, and Energy
  • Temperature: Measure of heat energy in an object (Celsius, Kelvin).
  • Specific Heat: Amount of heat needed to change temperature of 1 g of a substance by 1 °C.
  • Energy: SI unit - Joule (J); also expressed as calorie (cal).
1.12 Density and Specific Gravity
  • Density: Mass per unit volume (solids: g/cm³, liquids: g/mL).
  • Specific Gravity: Density of substance divided by the density of water; numerically equal to density at normal temp.
  • Relation of Density:
    • Less dense substances float on more dense fluids.