Study Notes on Physical and Chemical Properties and Changes of Matter

Physical/Chemical Properties and Changes of Matter

Definition of Properties

  • Properties are characteristics that describe matter.

Physical Properties

  • Definition: Physical properties can be observed without changing the substance's chemical makeup.
  • Examples of Physical Properties:
    • Color: The visual appearance of the material.
    • Smell: The scent or odor emitted by the substance.
    • Size: The dimensions of the object (length, width, height).
    • Weight: The force exerted by gravity on the object.
    • Mass: The quantity of matter contained in the object.
    • Volume: The amount of space an object occupies.
    • State of Matter: The form the matter takes (solid, liquid, gas).
    • Density: The mass per unit volume of a substance, calculated as Density=MassVolumeDensity = \frac{Mass}{Volume}.
    • Conductivity: The ability of a substance to transfer heat or electricity.
    • Magnetism: The property of being attracted to or repelled by a magnetic field.
    • Hardness: The resistance of a material to deformation or scratching.
    • Malleability: The ability of a material to be deformed under compressive stress, typically the ability to be hammered into thin sheets.
    • Temperature: A measure of the average kinetic energy of the particles in a substance, influencing states of matter such as freezing, melting, and boiling.
    • Ability to Change Shape: The capacity for physical deformation without altering the substance's identity.

Chemical Properties

  • Definition: Chemical properties can only be observed by altering the chemical composition of the substance.
  • Examples of Chemical Properties:
    • Flammability: The ability of a substance to burn in the presence of oxygen.
    • pH Level: The acidity or basicity of a substance, indicating the concentration of hydrogen ions present.
    • Reactivity: The ability of a substance to undergo chemical reactions with other substances, forming new compounds.
    • Oxidation: A chemical reaction that involves the transfer of electrons, typically involving a substance reacting with oxygen.

Physical Changes

  • Definition: A physical change involves a change in appearance or state without altering the substance's chemical composition.
  • Examples of Physical Changes:
    • Color Change: Applying paint on a canvas; the base material (canvas) remains unchanged.
    • Melting: The phase transition of chocolate in sunlight—although it melts, it remains chocolate.
    • Phase Changes: Transitions between states of matter, such as ice becoming water (melting), water becoming steam (boiling), and reversing back to ice (freezing).
    • Shape Changing: Actions like tearing paper or breaking glass which do not alter the material's chemical identity, it remains paper or glass respectively.
    • Form Changes: Shaping playdough; it maintains its identity despite changing forms.

Chemical Changes

  • Definition: Chemical changes involve a substance transforming into a different substance due to changes in its chemical structure.
  • Examples of Chemical Changes:
    • Color Change: When bread dough bakes, a change in color indicates a chemical reaction and transformation.
    • Odor Change: The smell from rotting milk indicates chemical breakdown and new substance formation.
    • Gas Production: Mixing baking soda with vinegar produces carbon dioxide (CO₂) gas, a clear indication of a chemical reaction.
    • Energy Release: Reactions such as fireworks produce light and heat energy, signifying a chemical change.