Matter Measurement and Problem Solving Atoms and Molecules, Inquiry, Classification of Matter, and physical and chemical changes

What is chemistry? Studies matter, including changes involving matter and energy accompanying the change The science that seeks to understand behavior of matter by studying behavior of atoms and molecules

What is matter? UniverseMatter Has mass- Amount of matter Occupies volume Further classified by state and/ or purity Energy No mass or volume Ability to produce change Further classified by type of change (heat, work, etc.)

Atoms vs. Molecules Atom ◦ Most basic unit of matter ◦ Fundamental particles that are the building blocks of ordinary matter Molecule ◦ Atoms are typically not in isolation ◦ Group of atoms that are held together by chemical bonds

Scientific Method

Variables Math is used in every step of the scientific method- it is a tool of science Independent variable- x axis (set value) Dependent variable- y axis (responds to changes in x)

Experiment Allows determination of cause and effect Expressed as math relationship or graph

Determining Scientific Theory One or more well-established hypotheses may form basis for scientific theory

Scientific Theory vs. Scientific Law Theory- Well tested hypothesis ◦ Best explanation/ model ◦ General ◦ Can be used to predict ◦ Validated by experimentation but can never be conclusively proven Scientific Law – General summary of related observations ◦ Often in form of math relationship ◦ Subject to further verification by experiment ◦ NOTE- scientific law can be proven invalid by new data. (e.g. Law of Conservation of Mass invalid for nuclear reactions)

Properties of Matter Observable, measureable characteristics Use to describe, classify, and identify Expressed as either qualitative or quantitative

Physical States of Matter

Types of Solids Crystalline Solid ◦ Atoms or molecules are arranged in repeating patterns Amorphous Solid ◦ Atoms or molecules do not have any long range order

Qualitative vs. Quantitative ◦ Qualitative  Estimated  No measuring device needed ◦ Quantitative  Value + appropriate units  Need to use measuring device/ instrument

Quantitative Properties Reliable measurements need… ◦ Proper selection, use of measurement device ◦ Appropriate set of units (metrics/ SI units) Scientific Notation ◦ Ability to compactly express large and small numbers Dimensional Analysis ◦ Convert units as necessary ◦ Factor- label, unit factor

Intensive vs. Extensive properties Intensive Properties ◦ Do not depend on size, extent, amount ◦ Only depend on identity, purity and conditions of measurement (temperature, pressure) ◦ Not additive Extensive Properties ◦ DO depend on the amount ◦ Are additive ◦ Different materials can have same value Properties are EITHER intensive or extensive, not both

Intensive vs. Extensive Intensive or Extensive? Color Odor Mass Weight Malleability Volume Melting or freezing point Density Hardness Length Conductivity

Types of Matter Pure Substances ◦ Substance made of a single type of atom or molecule ◦ Broken into elements and compounds  Elements- substance that cannot be broken into simpler substances  Compound- substance composed of two or more substances

Types of Matter Mixtures ◦ Combination of two or more pure substances  Homogeneous  Two or more substances mixed with same composition  Solution  Does not settle out over time  Heterogeneous  Two or more pure substances with varied composition  Does settle out over time  Colloids and suspensions

Classification of Matter

Classification of Matter Practice Element, Compound, Heterogeneous Mixture or Homogeneous Mixture Jello Mint chocolate chip ice cream Chicken noodle soup Helium Water Diamond Tea Iced tea Sour cream Peanut butter Sodium chloride Carbon dioxide Oxygen

Physical and Chemical Changes Physical Change Physical Property Alters only state or appearance Extensive PropertyChanges back easily Still considered same thing afterwards Chemical Change Chemical property Atoms rearrange into different substance Intensive Property Needs chemical reaction to change back No longer considered original substance

Physical or Chemical Change? Butter melting Wood rotting Melting gold Grating cheese Turning sugar to caramel Nail rusting Digesting food Lighting a stove Tearing paper