MLS Chemistry Chapter 2: Matter and Energy

Classification of Matter

• Matter is defined as anything that has mass and occupies space.
• Traditionally categorized into three states: solid, liquid, gas, with two additional states identified: plasma and Bose-Einstein Condensate.
• Pure Substances: Uniform chemical composition with distinct properties.
  • Elements: Cannot be separated into simpler substances (e.g., H, He, O).
  • Compounds: Composed of two or more elements in fixed proportions, separable by chemical means (e.g., H₂O, NaCl).
• Mixtures: Comprises two or more pure substances retaining their identities and separable by physical methods.
  • Homogeneous Mixtures: Uniform composition (e.g., solutions like vinegar).
  • Heterogeneous Mixtures: Non-uniform composition (e.g., colloids like milk, suspensions like muddy water).

States/Phases of Matter

• Solid: Fixed shape and volume; high density; incompressible; slight thermal expansion.
• Liquid: Takes the shape of its container; definite volume; medium density; can be compressed slightly.
• Gas: No fixed shape or volume; low density; highly compressible; significant thermal expansion.
• Plasma: Composed of ions and electrons; no definite shape/volume; typically found in high-energy environments.
• Bose-Einstein Condensate: Exists at near absolute zero; particles are highly correlated, showing quantum behavior on a macroscopic scale.

Properties and Changes of Matter

• Physical Properties: Observable or measurable without altering the substance (e.g., color, hardness, melting/boiling point).
• Chemical Properties: Ability of a substance to undergo chemical changes (e.g., flammability, reactivity).
  • Intensive Properties: Independent of amount (e.g., temperature, density).
  • Extensive Properties: Dependent on the amount (e.g., mass, volume).
• Phase Changes:
  • Melting: Solid to Liquid
  • Freezing: Liquid to Solid
  • Evaporation: Liquid to Gas
  • Condensation: Gas to Liquid
  • Sublimation: Solid to Gas
  • Deposition: Gas to Solid
  • Ionization: Gas to Plasma
  • Deionization: Plasma to Gas
  • Cooling to near absolute zero: Gas to Bose-Einstein Condensate

Fundamental Laws

• Law of Conservation of Matter: Matter is not created or destroyed; mass of reactants equals mass of products in a closed system.
• Law of Definite Composition: A compound always contains the same proportion of elements by mass (e.g., water is 11% hydrogen, 89% oxygen).
• Law of Multiple Proportions: When two elements form multiple compounds, the mass ratios of the second element are small whole numbers (e.g., CO and CO₂ have a 2:1 mass ratio of oxygen).

Dive into Chapter 2 of MLS Chemistry, focusing on matter and energy. This chapter covers the classification of matter, its states and phases, properties and changes, and fundamental laws governing matter. Perfect for grasping the core concepts of chemistry.