Physical Properties and Changes of Matter

Physical Properties of Matter

• Physical properties are characteristics that can be observed without changing the substance's identity.
• Examples of physical properties include: color, size, shape, state of matter (solid, liquid, gas), melting point, boiling point, magnetic properties, ductility, malleability, density, solubility, texture, and electrical conductivity.

Physical Changes

• A physical change alters the size, shape, or state of matter, but does not change the substance's chemical composition.
• Examples of physical changes include: melting, freezing, boiling, condensing, dissolving, crushing, and chopping.
• Phase changes are physical changes.

Phase Changes

• Phase changes involve a change in the state of matter (solid, liquid, gas).
• Examples of phase changes include: melting (solid to liquid), freezing (liquid to solid), vaporization (liquid to gas), condensation (gas to liquid), sublimation (solid to gas), and deposition (gas to solid).

Using Physical Properties to Separate Mixtures

• Physical properties can be used to separate mixtures into their individual components.
• Examples of methods include: distillation (separating substances based on their boiling points), and sieving (separating substances based on their size).

Chemical Properties

• Chemical properties describe how a substance changes into a different substance or how it reacts with other substances.
• Examples of chemical properties include: flammability, reactivity with light, reactivity with oxygen, reactivity with water, reactivity with acid, inertness (lack of reactivity), and electrolysis (reactivity with an electric current).
• Chemical properties determine if a particular process will be a chemical change.

Detecting Chemical Changes

• Chemical changes involve the formation of new substances, which can be detected through certain clues.
• Clues for detecting chemical changes include:
  • Change in odor or smell
  • Formation of bubbles or gases
  • Release or absorption of heat/energy
  • Change in color
  • Formation of a precipitate (solid that separates from a solution)
  • Emission of light or sound

During a Chemical Change

• New substances are formed.

Chemical Reaction of Sodium & Chlorine

• A chemical reaction between sodium and chlorine results in a new substance.

Law of Conservation of Mass

• Matter is neither created nor destroyed in a chemical reaction.
• The total mass of the reactants equals the total mass of the products.
• Atoms are rearranged in a chemical reaction to form different substances, but the total number of atoms remains the same.

Example Problems (Conservation of Mass)

• Example problem calculations show how to calculate the amount of a substance involved in a chemical reaction based on the amount of other substances involved using the law of conservation of mass..