Chapter 3 Matter

• Matter has mass and occupies space. It is composed of tiny particles called atoms.

• Matter exists in three states:

  • Solid—is a rigid substance with a definite shape

  • Liquid—has a definite volume but takes the shape of its
    container

  • Gas—takes the shape and volume of its container

• Matter has both physical and chemical properties.

  • Chemical properties describe a substance’s ability to change to
    a different substance.

  • Physical properties are the characteristics of a substance that
    do not involve changing to another substance. Examples are shape, size, and color.

• Matter undergoes physical and chemical changes.

  • A physical change involves a change in one or more physical
    properties but no change in composition.

  • A chemical change transforms a substance into one or more
    new substances.

• Elements contain only one kind of atom—elemental copper contains only copper atoms, and elemental gold contains only gold atoms.

• Compounds are substances that contain two or more kinds of atoms.

• Compounds often contain discrete molecules.

• A molecule contains atoms bound together in a particular way—
  an example is the water molecule, which is written H₂O.

• Matter can be classified as a mixture or a pure substance.

  • A mixture has variable composition.

    • A homogeneous mixture has the same properties throughout.

    • A heterogeneous mixture has different properties in different
      parts of the mixture.

    • A pure substance always has the same composition.

• Mixtures can be separated into pure substances by various means including distillation and filtration.

• Pure substances are of two types:

  • Elements, which cannot be broken down chemically into simpler
    substances.

  • Compounds, which can be broken down chemically into
    elements.