11/17/08

Post date: Nov 17, 2008 1:56:7 AM

Bell Activity: Give an example of a physical property.

    • Chemical properties

      • Describe how a substance changes into a new substance

        • By combining with other substances or

        • by breaking apart into new substances

      • Flammability - the ability to burn

      • Reactivity - the capacity of a substance to combine with another substance

        • Iron combines with oxygen to form rust

        • Hydrogen peroxide decomposes into water and oxygen

    • Changes of matter - Group presentations

      • Physical changes

        • Affects one or more physical properties of a substance without changing the identity of the substance

          • Melting - change of state, but same substance

          • Cutting - change of size, but same substance

          • Crushing - change of shape, but same substance

        • Dissolving is a physical change

          • Sugar dissolves in water, but you can still taste it

          • Water molecules spread out the molecules of the other substance, but don't alter them

      • Chemical changes

        • One or more substances are changed into entirely new substances with different properties

        • Can be detected by a change in taste, smell, color, etc.

        • Cannot be reversed by physical changes

      • Breaking down mixtures and compounds

        • Mixtures can be physically separated

        • Some compounds can be broken down through chemical changes

  • Pop quiz - Chapter 2, section 3 material from presentations