Matter, Change and Energy

Review

Physical Change A change that DOES NOT change the chemical compostion of a substance. Examples: melting (and all phase changes), tearing or breaking.

States of Matter Solid – slower moving particles, strong attractions, definite volume and shape. Liquid – particles move faster than solids, moderate intermolecular attractions, definite volume, no definite shape. Gas – rapidly moving particles, almost no intermolecular attractions, no definite volume, no definite shape.

Changes of States of Matter Enthalpy- total energy of a system (often mostly in the form of heat). Remember: A change of state is a physical change.

Solid, liquid, or gas? Solid Liquid Gas

Chemical Changes Are also known as chemical reactions. Involve energy. Make a new substance by rearranging atoms. Are not easily reversed. Are expressed in a chemical equation:

Signs of Chemical Change Uses or release heat or light or other forms of energy Changes color Effuses gas (bubbles) Forms a precipitant (a not soluble solid) Odor changes

Symbol

Classification of Matter General Matter Homogeneous Heterogeneous Pure Substance Homogeneous Mixture Heterogeneous Mixture Element Compound Solution Mixture Specific Order ----------------------------------------------------Disorder

Elements One kind of matter (one kind of atom).

Compounds Two or more different elements chemically combined in a fixed ratio. Elements have different properties together, than separate.

Compounds: The Laws of Definite and Multiple Proportions Law of Definite Proportions: The ratios of elements in compounds do not change. Law of Multiple Proportions: If you change the ratio of elements, it is no longer the same compound. Example: H2O is water H2O2 is hydrogen peroxide They are very different!

Allotropes Allotrope: Compounds made of a single element. Allotropes: Not Allotropes: Carbon Allotropes:

Heterogeneous: Simple Mixtures Any two things together with the parts visible. Can be separated easily. Heterogeneous Homogeneous

Separating Mixtures Filtering Decanting Boiling or Distilling Magnets

Homogeneous Mixtures: Solutions When one substance dissolves (disappears) in another because the atoms or ions separate. Are transparent, but may be clear or colored. Two parts: Solute (disappears) and Solvent.

Heterogeneous mixtures: Suspensions Appears homogeneous, but eventually settles or separates. Are cloudy

Hetero- or Homogeneous mixture? Colloids A permanent suspension because the particles are so tiny. Are cloudy Often have a Tyndall Effect.

Introduction to the Periodic Table

The End