CHAPTER 15

Classification of Matter

Classification of Matter

ESSENTIAL QUESTIONS:• WHAT IS MATTER? • HOW DO WE CLASSIFY MATTER? • WHAT ARE PHYSICAL AND CHEMICAL

CHANGES?

Composition of Matter

• Properties of materials are used to classify them.

• The two main categories are – PURE SUBSTANCES and – MIXTURES

PURE SUBSTANCES

• A type of matter with a fixed composition.• ELEMENT: a substance that contains ONE TYPE

of atom: copper, carbon (graphite/diamond) and oxygen (O2)..

PURE SUBSTANCES

• A type of matter with a fixed composition.• COMPOUND: a substance in which the atoms

of two or more elements are combined in a fixed proportion: H2O, CaCO3, CO2, and NaCl.

• The compound properties are often different from the elements that make them

MIXTURES

• A type of matter with NO fixed composition.• HETEROGENEOUS MIXTURES: different

materials are distinguished easily: pizza, soup mix, and granite.

• Not all are easily recognized

MIXTURES

• HOMOGENEOUS MIXTURES: contains two or more gaseous, liquid or solid substances blended evenly throughout: soda, air, sea water, and vinegar.

• These are also known as SOLUTIONS: a homogeneous mixture of particles that are CONSTANTLY and UNIFORMLY mixed.

MIXTURES

• COLLOID: a mixture with particles that are larger than a solution, but not heavy enough to settle out: milk (water, sugars, fats, proteins), paint (oil, pigment, etc), fog (air, liquids), and smoke in air.

MIXTURES

• SUSPENSIONS: heterogeneous mixture containing a liquid in which the particles settle.

PROPERTIES OF MATTER

• Using physical properties to separate – sifting, sorting, using a magnet, etc. RECYCLING.

Section 15.2: PHYSICAL & CHEMICAL CHANGES OF MATTER

• PHYSICAL CHANGE: a change in size, shape, or state of matter. THE IDENTITY REMAINS THE SAME.

• These changes may involve energy changes but the properties don’t change. E.g. iron when heated.

PHYSICAL & CHEMICAL CHANGES OF MATTER

• PHYSICAL CHANGE: a change in size, shape, or state of matter. THE IDENTITY REMAINS THE SAME.

• DISTILLATION – Uses a physical change to separate (evaporation). Used in industry.

CHEMICAL PROPERTIES & CHANGES

• CHEMICAL PROPERTY – A characteristic of a substance that indicates whether it can undergo a certain chemical change. E.g. flammable, changes color.

CHEMICAL PROPERTIES & CHANGES

• CHEMICAL CHANGE – produces heat, light, sound, color change, precipitate, and gas bubbles.

PHYSICAL & CHEMICAL CHANGES

• FOR EXAMPLE: WEATHERING• Physical – rocks broken apart by ice, streams carving

away rock, wind moving sand

• Chemical – Limestone (CaCO3) changes to gypsum in acid