CHM 105 chapter 1

General Chemistry Overview

Introduction to Chemistry

  • Chemistry: Study of matter, its properties, and changes it undergoes.

  • Matter: Anything with mass and occupies space.

  • Energy: Ability to do work.

The Discovery Process

  • Role of Chemistry: Influences various fields like public health, pharmaceuticals, food science, and forensic sciences.

Characteristics of the Discovery Process

  • Observation

  • Formulation of a question

  • Pattern recognition

  • Developing theories

  • Experimentation

  • Data: Results from a single measurement.

  • Results: Outcomes of experiments and summarization of information.

The Scientific Method

  • Systematic representation of scientific inquiry.

Classification of Matter

States of Matter

  1. Gas: Widely separated particles; no definite shape or volume.

  2. Liquid: Particles closer together; definite volume but no definite shape.

  3. Solid: Very close particles; definite shape and volume.

Composition of Matter

  • Pure Substance: Only one component.

  • Mixture: Combination of two or more substances retaining their identity.

    • Homogeneous Mixture: Uniform composition.

    • Heterogeneous Mixture: Non-uniform composition.

Types of Pure Substances

  • Element: Cannot be simplified.

  • Compound: Combination of two or more elements in fixed ratios.

Properties of Matter

Physical Properties vs. Physical Changes

  • Physical Property: Observed without altering composition.

  • Physical Change: Change in appearance without changing identity (e.g., melting).

Chemical Properties vs. Chemical Reactions

  • Chemical Property: Changes composition during reactions.

  • Chemical Reaction: Transformation leading to different substances.

Classifying Properties

  • Intensive Properties: Independent of substance amount (e.g., color).

  • Extensive Properties: Dependent on substance amount (e.g., mass).

Units of Measurement

Measurement Systems

  • English System: Unrelated units, challenging conversions.

  • Metric System: Decimal-based and systematic.

Key Measurements

  • Mass: Quantity of matter; measured in grams (g).

  • Volume: Space occupied; standard unit is liter (L).

  • Length: Distance measured in meters (m).

Significant Figures

  • Important in measurements to express confidence in data:

    • All nonzero digits significant.

    • Zeros matter based on their position.

    • Example: 4.70 (three significant figures).

Scientific Notation

Usage in Chemistry

  • Simplifies representation of large/small numbers.

  • Conversion rules based on decimal movements for numbers greater or lesser than 1.

Energy in Chemistry

Types of Energy

  • Kinetic: Energy of motion.

  • Potential: Stored energy.

Characteristics

  • Energy transformation occurs with less than 100% efficiency.

Units for Energy

  • Calorie and Joule are basic units.

Concentration, Density and Specific Gravity

Concentration

  • Measure of particle number/mass in a volume (e.g., gases, solutions).

Density

  • Ratio of mass to volume, significant for identifying substances.

  • Example Calculation: Density = mass/volume

Specific Gravity

  • Ratio of the density of a substance to that of water at 4°C; unitless and used in health assessments.