Chapter 3 - Chemsity

  • Matter

    • anything occupying space and having mass

    • matter exists in three states

      • soild

        • defined volume and shape

      • liquid

        • assumes the shape of container

        • has a defined volume

          • water, milk,

      • gas

        • no defined volume or shape

        • takes the shape and volume of its container

          • air, helium, oxygen

    • States of water

      • solid - ice

      • liquid - water

      • gas - steam

  • Physical and chemical properties and changes

    • Physical: characteristics that are directly observable and unique to a substance

      • ex. odor, color, volume, state, boiling, and melting point

    • Chemical: substrate's ability to form a new substance

      • Characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy

      • Ex. flammability, rusting of steel, digestion of food

        • Electrolysis of water

  • Elements and compounds

    • Element: a substance that cannot be broken down into other substances by chemical methods

      • Ex: Iron (Fe) Alumminun (AI)

    • All matter in the world around us contains elements

    • Compound: a substance composed of a given combination of elements that can be broken down into those elements by chemical methods

      • Ex: Water (H2O), carbon dioxide (CO2)

      • Always contains atoms of different elements

      • always has the same composition or the same combination of atmos

  • Mixed and Pure Substances

    • Pure substances

      • always have the same composition

      • are either elements or compounds

        • Ex: pure water, hydrogen, gold

    • Mixtures

      • have variable composition

        • Ex: wood, wine, and coffee

      • two or more pure substances

      • Homogeneous mixture

        • substance that is the same throughout

          • sometimes called a solution

        • consists of visibly indistinguishable parts

        • doesn’t vary in composition from one region to another

          • Ex: air around you, brass, table salt in water

      • Heterogeneous Mixture

        • visibly distinguishable parts

        • contain regions that have different properties from other regions

          • Ex: oil and vinegar dressing, sand stirred into water

  • Separation of mixtures

    • Separation based on physical properties

      • Mixtures can be separated based on different physical properties of the components

        • Boiling point → distillation

          • Salt water: no chemical change occurs when salt water is distilled

        • State of matter (solid/liquid/gas) → filtration

          • separates a liquid from a solid

        • Adherence to a surface → Chromatography

        • Volatility → Evaporation

  • Organization of matter