Chapter 2 Key Points


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Chapter 2 Key Points

  1. 1. Chapter 2.1/2.2 Key Points Max Waldbaum
  2. 2. Compounds and MixturesCompounds Mixtures• Are a chemical combination • Are a physical combination• Can only be broken down • Can only be broken down chemically physically• Always in a fixed ratio • Can be in any ratio (e.g. H20) (e.g. Cereal)• All compounds have a unique set of properties • No one unique set of (Characteristic properties properties, which are independent of amount)
  3. 3. Types of MixturesHomogeneous Mixture Heterogeneous Mixture• Very evenly distributed • Not uniform throughout substances • Parts are noticeably• Appears to only contain one different substance e.g. Honey Bunches of Oats e.g. Stainless Steel (Made of Cereal ( Made with different iron, chromium, and parts that look clearly nickel, but looks uniform) different)• Solutions and Colloids are • Suspensions are Homogeneous Heterogeneous
  4. 4. Heterogeneous and Homogeneous Mixtures ClassificationsSolutions Suspensions Colloids• A solution is when • A suspension is a • A colloid has substances heterogeneous particles larger than those of a dissolve creating a mixture that solution, but homogeneous separates into smaller than those mixture layers over time of a suspension. It is a homogenous mixture e.g. Lemonade e.g. Mixtures that e.g. Homogenized (Sugar and lemon State “Shake Well” milk (the fat juice dissolved in (If not, the remains dispersed water) different parts of throughout the the mixture will milk) layer)
  5. 5. Classifications of Matter Matter Pure Substance Mixture Homogeneous HeterogeneousElement Compound Mixture MixtureOne Substance Chemical Mix Solution, Colloid Suspension (Au) (H2O)
  6. 6. Physical Properties• A Physical Property is a characteristic of a material• Examples of Physical Properties are ..... – Viscosity (Residence to flowing- e.g. honey has a high viscosity) – Conductivity (Ability to allow heat to flow – e.g. metal has a high conductivity) – Malleability (Ability of a solid to be hammered without shattering – e.g. Gold is malleable) – Hardness (Which material is harder – e.g. scratch test) – Melting/Boiling Points – Density (How dense the material is – g/mL)
  7. 7. Using Physical Properties• Physical Properties are mainly used to...1. Identify a Material2. Choose a material for a specific purpose3. Separate the substances in a mixture• Physical properties are key in exercising these steps, which are used in many scientific findings and labs
  8. 8. Distillation• A process that separates the substances in a solution based on Boiling Point
  9. 9. Filtration• A process that separates particles based on the size of their particles and/or solubility
  10. 10. Evaporation• A process used to isolate a solid dissolved in a liquid. Property: Solubility• Ex: NaCl + Water – (Sodium Chloride) • Table Salt• DISCLAIMER: You are not going to isolate a pure sample of all components of the mixture
  11. 11. Observing Chemical Properties• Chemical properties can only be observed when the substances in a sample of matter are changing into different substances – Flammability • Is a materials ability to burn in the presence of oxygen – Reactivity • How easily a substance combines with another substance (Rust & Oxygen)
  12. 12. Recognizing Chemical Changes• Common types of evidence: – Change in color – Production of Gas – Formation of Precipitate
  13. 13. Difference Between Chemical and Physical Changes• Chemical changes: – Composition of a substance changes• Physical Changes – Composition remains the same
  14. 14. Questions for Test• What is a physical property?
  15. 15. Questions for Test• What is a chemical property?
  16. 16. What is a Physical Change?
  17. 17. What is a chemical change?
  18. 18. What are the four ways to recognize a chemical change?