T1 Atoms, Elements, Compounds, Mixtures

States of Matter

  • Three States of Matter: Solid, Liquid, Gas.
    • Depend on Particle Interactions:
    1. Material Type
    2. Temperature
    3. Pressure
Solids
  • Characteristics:
    • Strong forces of attraction hold particles in fixed positions, forming a regular lattice arrangement.
    • Particles vibrate in place but do not move freely, ensuring solids maintain a definite shape and volume.
    • Heating increases particle vibrations, causing solids to expand slightly.
Liquids
  • Characteristics:
    • Weaker forces of attraction between particles which allows some movement.
    • Random arrangement of particles, enabling them to flow and take the shape of their container while maintaining a definite volume.
    • Particle motion increases with temperature, causing liquids to expand slightly when heated.
Gases
  • Characteristics:
    • Very weak forces of attraction; particles are far apart and move freely.
    • Do not have a definite shape or volume and will expand to fill their container.
    • Increase in temperature results in faster particle movement; gases can either expand or increase in pressure when heated.

Changing States of Matter

  • Physical Changes: Rearranging of particles without altering their composition.
  • Key Processes:
    1. Melting: Solid to liquid (occurs when particles gain enough energy to break free from fixed positions).
    2. Freezing: Liquid to solid (loss of energy allows particles to settle into fixed positions).
    3. Evaporation: Liquid to gas (particles gain enough energy to break bonds).
    4. Condensation: Gas to liquid (particles lose energy and begin to stick together).
    5. Subliming: Direct transition from solid to gas.

Diffusion

  • Definition: Gradual movement of particles from areas of high concentration to low concentration.
  • Demonstration Experiments:
    • Potassium Manganate(VII) in Water:
    1. Adding crystals to water shows the diffusion of purple color as particles spread out amongst water particles.
    2. Adding more water dilutes the color, demonstrating the concept of dilution.
    • Ammonia and Hydrogen Chloride:
    1. In a closed tube, both gases diffuse and react to form ammonium chloride, with a white ring appearing closer to HCl end because of varying diffusion rates (NH3 diffusing faster).
    • Bromine Gas and Air:
    1. Brown bromine gas will diffuse into air when a barrier is removed, demonstrating diffusion in gases and their random motion.

Solutions

  • Definition: A homogeneous mixture of solute (substance dissolved) and solvent (substance it dissolves in).
  • Key Definitions:
    1. Solution: Mixture that does not separate out.
    2. Solute: The substance being dissolved.
    3. Solvent: The liquid in which the solute dissolves.
    4. Saturated Solution: Contains maximum solute that can dissolve without excess precipitate.
Solubility
  • Definition: Measure of how much solute can dissolve in a solvent, often expressed in g/100g of solvent.
    • Solubility typically increases with temperature.
  • Investigating Solubility:
    • Method for ammonium chloride involves creating a saturated solution, weighing, and evaporating water to measure solid remaining.

Mixtures & Compounds

  • Elements: Consist of only one type of atom (e.g., copper, oxygen).
  • Compounds: Substances formed from two or more different elements chemically bonded (e.g., carbon dioxide - CO₂).
  • Differences from Mixtures:
    • Mixtures have no chemical bonds and can usually be separated by physical methods.
    • The properties of a mixture reflect the properties of its components (e.g., iron and sulfur).

Filtration and Crystallization

  • Filtration: Used to separate insoluble solids from liquids
    • Example: Filtering a mixture to separate sand from saltwater.
  • Crystallization: Used to separate soluble solids from a solution by evaporation to form crystals.

Chromatography

  • Method: Used to separate different components of mixtures by using a solvent to carry them up filter paper.
    • R-value calculation: Measure distances traveled by solute and solvent to establish ratios for identification.

Distillation

  • Types:
    1. Simple Distillation: Separates liquids from solutions by boiling point differences.
    2. Fractional Distillation: Separates liquids with closer boiling points using a fractionating column.
    • Example: Distilling seawater to obtain pure water.