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Chp 2. MATTER & MATERIALS

Chp 2. MATTER & MATERIALS. 2.1 Chemistry. A branch of science that deals with the composition, structure, properties and reactions (transformations) of matter. 2.1 DESCRIPTION OF MATTER. (anything that has mass and occupies space). Substances that are visible and invisible.

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Chp 2. MATTER & MATERIALS

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  1. Chp 2. MATTER & MATERIALS

  2. 2.1 Chemistry A branch of science that deals with the composition, structure, properties and reactions (transformations) of matter.

  3. 2.1 DESCRIPTION OF MATTER (anything that has mass and occupies space) Substances that are visible and invisible Substances that are living and nonliving

  4. (E.g., heat, light, electricity) 2.1 Matter doesn’t include energy, in its various forms All transformations of matter involve energy changes. Chemist are interested in the energy changes that occur when matter is transformed.

  5. MATTER no yes Can it be physically separated? MIXTURE PURE SUBSTANCE

  6. 2.2 Pure Substance (Substance) Matter that cannot be separated into other kinds of matter using physical means. It has a fixed composition and distinct properties. Examples Sugar, ammonia, water, and oxygen.

  7. 2.2 Mixtures Matter containing 2 or more substances in which each substance retains its own identity. Separable into individual substances by physical means. Mixtures can exist in any combination of pure substances. Therefore the composition of a mixture is variable.

  8. MATTER yes no Can it be physically separated? PURE SUBSTANCE MIXTURE • Physical combination of two or more substances • Variable composition • Properties vary as composition varies • Components can be separated by physical means • Only one substance present • Definite and constant composition • Properties are always same under given set of conditions

  9. 2.10 PHYSICAL SEPARATION METHODS • Use physical properties and changes to separate mixtures. • Melting point (freezing point) • Boiling point (condensation point) • Water solubility (dissolving) • Density • Techniques include: • Distillation • Filtration • Magnetism • Floatation

  10. 2.2 Mixture subclassifications Heterogeneous Homogeneous

  11. MATTER no yes Can it be physically separated? MIXTURE PURE SUBSTANCE yes no Is the composition uniform? Homogeneous Mixture (solution) Heterogeneous Mixture These are physical classifications based on observation of the matter

  12. Heterogeneous Homogeneous • A mixture is a variable combination of 2 or more pure substances.

  13. Homogeneous (solution) • One visibly distinguishable phase (uniform appearance) • Uniform properties throughout the phase • particles don’t settle • EX: rubbing alcohol

  14. Heterogeneous • Observe two or more visible phases • Each phase has different properties • particles settle • EX: fresh-squeezed lemonade

  15. 2.2 Pure Substances MATTER no yes Can it be physically separated? PURE SUBSTANCE MIXTURE no yes Can it be chemically decomposed? yes no Is the composition uniform? Compound Element Homogeneous Mixture (solution) Heterogeneous Mixture

  16. 2.2 Pure Substances • Element • composed of identical atoms • Cannot be broken down into simpler substances using chemical methods • EX: copper wire, aluminum foil

  17. COMPOUND • composed of 2 or more elements in a fixed ratio • properties differ from those of individual elements • Cannot be separated by physical means • Separated by chemical means • EX: table salt (NaCl)

  18. Substances and Mixtures • Examples: • Graphite (all C atoms) • pepper • sugar (sucrose) • paint • gasoline

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