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? SolidLiquidGas

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

Classification of Matter General SpecificOrder   Disorder Matter HomogeneousHeterogeneous Pure Substance Homogeneous Mixture Heterogeneous Mixture Element Compound Solution Mixture Symbol

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: H 2 O is water H 2 O 2 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. HomogeneousHeterogeneous

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