Working with the Properties & Changes of Matter
- Chemical- any substance that has defined composition
- Everything you see is made up of chemicals
- Even things you cannot see are made up of chemicals
- Some exist naturally
- Some are manufactured
- Chemical Reaction- the process by which one or more substances change to produce one or more different substances
Physical States of Matter
Type and arrangement of particles in a sample of matter determine the properties of the matter
Most matter is one of the three states of matter
A. Properties of the Physical State
Solids- fixed volume and shape
Rigid structure
Liquids- fixed volume and variable shape
Takes shape of container
Gases- neither fixed volume or shape
Particles move independently
Will fill any container they occupy
Changes of Matter
Many changes of matter happen. Changes occur in two different ways:
-
Physical Changes
Chemical Changes
A. Physical Change
Changes in which the identity of a substance doesn’t change
-Changes state
-Dissolving
-Crushing
B. Chemical Changes
Identifies of substances change and new substances form.
Mercury (II) oxide mercury + oxygen
Reactants Products
-Substance or molecule that -Substance that forms in a chemical
participates in a chemical reaction reaction
Atoms are not destroyed or created, so mass does not change during a chemical reaction.
C. Evidence of Chemical Change
Generally, evidence that a chemical change may be happening falls into one of four categories; you may observe more than one.
- Evolution of a gas- the production of a gas is often observed by bubbling or by a change in color
- Formation of a Precipitate- when two clear solutions are mixed and become cloudy, a solid precipitate has formed
- Release or Absorption of Energy- change in temperature of the giving off of light energy are signs of energy transfer
- Color Change in the Reaction System- look for a different color when two chemicals react