The Science of Matter Chapter 1

What is Chemistry? The investigation of the properties and interactions of matter.

Matter is anything that has mass and takes up space. ▫Mass: the amount of matter in an object.  NOT THE SAME AS WEIGHT  Weight is the gravitational force upon that matter.

Properties of Matter Physical Properties: things that can be directly observed Chemical Properties: things that can only be observed by changing the object being studied

Macroscopic vs. Submicroscopic Macroscopic: ▫Matter that is large enough to be seen.  All observations of the composition and behavior of matter are made from macroscopic level. Submicroscopic: ▫Matter that cannot be seen with any microscope.  The realm of atoms and their structures. The submicroscopic realm produces an understanding of why or how matter interacts or behaves in the way it does.

Models Models are used in chemistry to understand and think about the submicroscopic views. A model is a thinking device that helps you understand and explain macroscopic observations based upon experimentation.

Classifying Matter 2 Main groups: ▫Pure substances: matter with the same fixed composition and properties  Elements  Compounds ▫Mixtures: a blend of 2 or more substances  Not chemically combined

Mixtures homogeneous mixture: a mixture that is the same throughout. ▫Cannot visibly see different parts.  solutions (saltwater, air) heterogeneous mixture: has visibly different parts. ▫chocolate chip cookies

Solutions Homogeneous mixtures ▫Air ▫Saltwater ▫Alloys Solution Parts: ▫Solute: ▫Solvent: ▫Aqueous solution:

Separation of Mixtures Occurs by physical means (with physical changes) ▫Does not change the chemical identity of the substance. Separation Techniques: ▫Chromatography ▫Distillation ▫Evaporation ▫Filtering ▫Sorting

Homework: Pg ▫#1-10 All ▫Due Monday 9/9/13

Pure Substances Elements: ▫A substance that cannot be broken down into simpler substances. ▫~118 known elements ▫Organized in the periodic table ▫Symbolized with a 1 or 2 letter abreviation.  1 st letter is capitalized, 2 nd is lowercase.  Ex: O, Al, Br, H, U, Cu, K

Pure Substances Compounds: ▫Substances that are composed of 2 or more elements chemically combined in a fixed proportion.  Ex: water is always 88.8% O and 11.2% H by mass ▫Cannot be separated into simpler substances without losing the compounds original properties. ▫Shown with chemical formulas  Ex: C 12 H 22 O 11, CO 2

Classifying Matter by Composition Qualitative: an expression without measurement or numbers. ▫Tells what something is made of. Quantitative: a numeric expression of composition based on measurement. ▫Ex: sucrose is composed of 42.1% C, 51.4% O, and 6.5% H.

States of Matter 4 possible states: solid, liquid, gas, or plasma ▫Characterized by the arrangement and movement of the atoms. State of matter is dependent upon temperature. Changes in state occur by heating or cooling past Freezing or Boiling Points. Volatile: substances that can easily go to a gas at room temperature ▫Ex: gasoline, alcohol, mothballs (naphthalene)

Changes in Matter Physical vs. Chemical

Physical Changes Any change that does not result in the formation of a new substance ▫Does not change the chemical composition of the substance. ▫Ex: tearing, heating, cooling, dissolving, evaporating, freezing, melting, condensing

Chemical Changes A change that results in the formation of 1 or more new substances. ▫Changes the chemical composition of the original substance. ▫Always involves a chemical reaction ▫Ex: burning, rusting, decomposition, etc.

Chemical Reactions Involves the breaking of existing bonds within a material, rearrangement of the atoms, and the formation of new bonds. Law of Conservation of Mass: mass is neither created or destroyed in a chemical change.

Chemical Reactions and Energy Energy: the capacity to do work or create heat. All reactions involve energy ▫Exothermic: reactions that involve a net release of energy  Ex: burning a bottle of gasoline ▫Endothermic: reactions that involve a net absorption of energy  Ex: cold packs, Photosynthesis

Homework Chapter 1 Review Pgs #1, 2, 5-8, 10, 13-19, 24, 29, 36, 47, 57 Due Wednesday 9/11/13