Chemistry I Notes Unit 1. Chemistry study of the composition, structure, and properties of matter and the changes it undergoes.

Transcription

1 Chemistry I Notes Unit 1 Chemistry study of the composition, structure, and properties of matter and the changes it undergoes. Questions of Chemistry 1. What is the material made of? 2. What it its makeup and internal arrangement? 3. How does it behave? Six Main Branches (Fields) of Chemistry 1. Organic Chemistry the study of most carbon-containing compounds 2. Inorganic Chemistry the study of all substance not classified as organic, mainly those that do not contain carbon 3. Physical Chemistry the study of the properties, changes, and relationships between energy and matter 4. Analytical Chemistry the identification of the components and composition of materials 5. Biochemistry the study of substances and processes occurring in living things 6. Theoretical Chemistry the use of mathematics and computers to design and predict the properties of new compounds. Basic Research is carried out to increase knowledge. Applied Research is carried out to solve a problem. Technological Development involves the production and use of products that improve our quality of life. Technology is anything that improves our quality of life. Volume the amount of space an object takes up Mass a measure of the amount of matter Matter anything that has mass and takes up space 2 Groups of Matter 1. Pure Substances material whose composition is the same throughout and does not vary from sample to sample (Elements and Compounds) 2. Mixture a blend of 2 or more kinds of matter, each of which retains its own identity and properties. (can usually be separated) Building Blocks of Matter Atom the smallest unit of an element that has all the properties of that element Element a pure substance made of only one kind of atom Compound a substance that is made from the atoms of 2 or more elements that are chemically bonded

2 Types of Mixtures A. Homogeneous Mixtures mixtures that are uniform in composition also called solutions (Example: salt and water) B. Heterogeneous Mixture mixture that is not uniform throughout (Example: supreme pizza no two slices are exactly the same) Image Source: Retrieved online: October 23, 2014 Types of Properties Physical Properties a characteristic that can be observed or measured without changing the identity of the substance A. Extensive physical property depend on the amount of matter that is present (mass, volume) B. Intensive physical property properties that do not depend on the amount of matter present (melting point, boiling point, density, conductivity) Chemical Properties relate to a substance s ability to undergo a chemical reaction (reacts with water to produce hydrogen gas or dissolves in water to produce a base solution) Physical Change a change in a substance that does not change the identity of the substance change of state Common Phase Changes Melting changing from a solid to a liquid Freezing changing from a liquid to a solid Vaporization changing from a liquid to a gas Condensation changing from a gas to a liquid Sublimation changing directly from a solid to a gas Deposition changing from a gas directly to a solid Image Source: Retrieved online: October 23, 2014

3 4 States of Matter 1. Solid definite shape and volume 2. Liquid definite volume but no definite shape 3. Gas no definite shape or volume 4. Plasma super heated electrically charged particles no definite shape of volume (found in sun or lightening) Image Source: Retrieved online: October 23, 2014 A change of state is a physical change of a substance. Solid state definite volume, definite shape. Solids have a strong attraction between individual particles. Crystalline solid solids with a regular geometric lattice Image Source: Retrieved online: October 23, 2014 Amorphous solid solid without a regular geometric lattice. Image Source: Retrieved online: October 23, 2014

4 liquid state definite volume, indefinite shape. Image Source: +Liquid+molecules.JPG. Retrieved online: October 23, 2014 Gas state--no definite volume, no definite shape. Gases have little or no attraction between individual particles. Image Source: Retrieved online: October 23, 2014 Plasma is a high-temperature physical state of matter in which atoms lose most of their electrons, particles that make up atoms. Image: Retrieved online: October 23, 2014 Chemical Change chemical reaction a change in which one or more substances are converted into different substances Reactants the substances present at the beginning of a chemical reaction Products the substances present at the end of a chemical reaction. Image Source: Retrieved online: October 23, 2014

5 Indicators of a Chemical Reaction (a chemical change) 1. Production of a gas (bubbling) Image Source: Retrieved October 24, Color change Image Source: Retrieved October 23, Production of Heat or Light and/or Temperature Change (temperature change my also indicate a physical change, so be careful with this one) 4. Production of a precipitate Image Source: October 23, 2014 Image Source: Retrieved October 23, 2014

6 Law of Conservation of Mass the total number of atoms participating in a chemical reaction remains the same (matter cannot be created or destroyed, but can be changed in form) Image Source: Retrieved online: October 23, 2014 Law of Conservation of Energy energy cannot be created or destroyed; it can only be changed in form Basics of the Periodic Table Groups or Families the vertical columns of the periodic table elements in a group have similar properties 18 groups Image Source: Retrieved online: October 23, 2014 Periods the horizontal rows of elements in the periodic table. The closer two elements are in a period, the more similar they are 7 periods Image Source: Retrieved online: October 23, Types of Elements 1. Metals located on left side of stair-step line Good conductors of heat and electricity Most are solids at room temperature (exception Hg) Malleable can be hammered into thin sheets Ductile can be drawn into fine wires Has luster shiny 2. Nonmetals located on right side of stair-step line Poor conductors of heat and electricity Solids, liquids, or gases at room temperature Not malleable or ductile (solid nonmetals are brittle)

7 Dull (not shiny) 3. Metalloids located on stair-step line Metalloid elements Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), and Tellurium (Te) Some characteristics of metals and nonmetals All solids at room temperature Less malleable than metals, but not as brittle as nonmetals Semiconductors of heat and electricity Some luster Image Source: Retrieved online: October 23, 2014 Noble Gases Group 18 Generally unreactive elements (reactive under special conditions only) All gases at room temperature Image Source: Retrieved online: October 23, 2014 Scientific Method logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypothesis, and formulating theories that are supported by data. The Scientific Method 1. Make an observation 2. Collect data 3. Form a hypothesis (a testable statement about an observation) 4. Test hypothesis (experiment) 5. Draw conclusion (is hypothesis supported or rejected) Theory a theory that has stood the test of time

8 Law rule of nature Image Source: Retrieved online: October 23, Types of Data 1. Qualitative data descriptive data 2. Quantitative data numerical data Image Source: Retrieved online: October 23, 2014 Quantity something that has magnitude, size, or amount SI Metric System standard unit of measurement used throughout the world based on the number 10 SI Base Units

9 SI Prefixes Mass measure of the amount of matter in an object (using a balance) Weight measure of the gravitational pull on matter (using a spring scale) Mass is constant; weight changes with location Length distance from one point to another Derived unit combinations of SI base units produced by multiplying or dividing standard units. Volume amt. of space an object takes up Common units for volume cm 3, L, ml Density the ratio of mass to volume Density Formula Image Source: Retrieved Online October 23, 2014 Conversion Factors a fraction equal to 1. Accuracy the closeness of measurements to the correct or accepted value of the quantity measured Precision the closeness of a set of measurements to one another Image Source: Retrieved online: October 23, 2014

10 Percentage Error Formula % error =!"#!$%&!'()*!"#$%!!""#$%#&!"#$%!""#$%#&!"#$% 100 In this equation, the experimental value comes from your experiment and the accepted value comes from a reliable source (such as a textbook or resource handbook). Significant Digits consist of all the digits known with certainty plus one final digit, which is somewhat uncertain or is estimated Rules for Significant Digits 1. All numbers other than zero are significant (1-9). 2. Zeros between two nonzero digits are significant. 3. Final zeros after a decimal are significant. 4. Zeros in front of nonzero digits are not significant (they are placeholders only). 5. Zeros in numbers that do not contain a decimal are not significant; zeros at the end of a number before a decimal are significant. 6. Addition/Subtraction final answer has the fewest number of significant digits after the decimal as shown in the problem. 7. Multiplication/Division the product or quotient contains the same number of significant digits as the measurement with the least number of significant digits. Graphing Relationships Directly Proportional the relationship between two variables if dividing one value by the other produces a constant value. Example: If one value being measured increases, the other value also increases. Image Source: Retrieved online: October 23, 2014 Inversely Proportional the relationship between two variables whose product is a constant value. Example: If one value being measured increases, the other value decreases. Image Source: Retrieved online: October 23, 2014