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SOL PS.2 The nature of matter
    PS.2 The student will investigate and understand the nature of matter. Key concepts include
  1. the particle theory of matter
  2. elements, compounds, mixtures, acids, bases, and salts
  3. solids, liquids, and gases
  4. physical properties
  5. chemical properties
  6. characteristics of types of matter based on physical and chemical properties
Matter
  • Matter is anything that has mass and occupies space.
    • All matter is made up of small particles called atoms.
    • Matter can exist as a solid, a liquid, a gas, or plasma.

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solid

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liquid

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gas
  • Matter can be classified as elements, compounds, and mixtures.
    • The atoms of any element are alike but are different from atoms of other elements.
    • Compounds consist of two or more elements that are chemically combined in a fixed ratio.
    • Mixtures also consist of two or more substances, but the substances are not chemically combined.

  • Compounds can be classified in several ways, including: - acids, bases, salts - inorganic and organic compounds.
Acids
  • Acids make up an important group of compounds that contain hydrogen ions.
    • When acids dissolve in water, hydrogen ions (H+) are released into the resulting solution.
    • A base is a substance that releases hydroxide ions (OH–) into solution.
    • pH is a measure of the hydrogen ion concentration in a solution.
    • The pH scale ranges from 0–14.
      • Solutions with a pH lower than 7 are acidic;
      • solutions with a pH greater than 7 are basic.
      • A pH of 7 is neutral.
    • When an acid reacts with a base, a salt is formed, along with water.
Physical Properties
  • Matter can be described by its
    physical properties, which include
    • shape
    • density
    • solubility
    • odor
    • melting point
    • boiling point
    • color


  • Some physical properties, such as density, boiling point, and solubility, are characteristic of a specific substance and do not depend on the size of the sample.
  • Characteristic properties can be used to identify unknown substances.
  • Equal volumes of different substances usually have different masses.





Chemical Properties
  • Matter can also be described by its chemical properties, which include
    • acidity
    • basicity
    • combustibility (how easily it catches fire)
    • reactivity

  • A chemical property indicates whether a substance can undergo a chemical change.

STUDENTS SHOULD BE ABLE TO

MATTER
  • describe the particle theory of matter.
  • describe the properties of solids, liquids, gases, and plasma.
  • describe how to determine whether a substance is an element, compound, or mixture.
  • define compounds as inorganic or organic. (All organic compounds contain carbon).
ACIDS
  • describe what a salt is and explain how salts form.
  • analyze the pH of a solution and classify it as acidic, basic, or neutral.
PROPERTIES
  • distinguish between physical properties and chemical properties..
  • find the mass and volume of substances and calculate and compare their densities.
  • determine the identity of an unknown substance by comparing its properties to those of known substances.
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