Definitions of Chemistry

• Chemistry deals with the properties of materials and the changes these materials undergo. (DLB, 7th Ed., Prentice-Hall)

• Chemistry is a physical science that deals with the composition, structure and properties of substances and the reactions they undergo. As a science, chemistry involves the intuitive and creative application of knowledge gained from experiment observation and theoretical descriptions.

• Anything that bites or scratches is biology

  Anything that stinks or pops is chemistry

  Anything that does not work is physics

Definition of Matter

The two distinguishing characteristics of matter is that matter is classified as anything that has mass and occupies space.

Composition of Matter

• Pure substances

  • matter that has a fixed composition and distinct physical and chemical properties.

    • Atoms

      Matter is composed of atoms.

      • Atoms are the smallest particles of an element that retain the chemical properties of the element.

      • An element is an example of matter which consists of only one kind of atom, either individually or combined into larger units.

  • Molecules

    • Molecules are units of matter consisting of two or more atoms combined in a definite ratio.

      When the atoms are the same in a molecule the substance is an element.

      When the atoms are different the substance is considered a compound.