Chemistry I – Unit 1 Notes Chapters 1-3 Chemistry the Central Science

1. Chemistry I – Unit 1 NotesChapters 1-3Chemistry the Central Science Mr. Seaney Ch. 1

2. Table of Contents 1.1 Scope of Chemistry 1.2 Chemistry and You- Safety in the Laboratory 1.3 Thinking like a scientist 1.4 Problem Solving 2.1 Properties of Matter 2.2 Mixtures 2.3 Elements and Compounds 2.4 Chemical Reactions 3.1 Using and Expressing Measurements 3.2 Units of Measurement 3.3 Solving conversion problems

3. 1.1 Scope of Chemistry The study of substances and changes they undergo • Chemistry in action – touches every aspect of life • The study of matter,5 areas : Organic, Inorganic, Biochemistry, Analytical, Physical C. Big Ideas 1. Chemistry as the central science 2. Electrons and atomic structure 3. Bonding and interactions 4. Reactions 5. Kinetic Theory 6. The mole and quantifying matter 7. Matter and energy 8. Carbon Chemistry

4. Know Your Safety Symbols • See Text appendix C page R50 • Memorize the equipment and symbols in your lab book for the test • Review the video study guides on lab safety

5. 1.2 Chemistry and you Safety in the Laboratory • Rules & Procedures • Follow teacher’s and lab directions • Notify teacher of problems • Know how to use safety equipment • Wear safety goggles at all times • Tie back long hair • Avoid awkward transfers • Let hot stuff cool or use tongs / hot mitts • Carry chemicals defensively • Dispose of wastes properly • Clean up after lab

6. 1.3 The Scientific Method • A way to answer questions and solve problems • Steps in the Scientific Method • Observation – Curiosity about nature • Question – Why or how the event occurs • Hypothesis – Proposed or tentative answer • Experiment – Test with variable & control • Conclusion – Analyze data interpret results • Natural Law – Explains how nature behaves • Theory – Explains why, allows prediction

7. Scientific Method Flow Chart Question Observe Hypothesis Experiment Reject Accept Natural Conclusion Law Theory

8. 1.4 Problem Solving • Use dimensional analysis (factor labeling) to solve word problems • Conversion factors should be used to cancel the units you don’t want and leave behind the units you do want • Always list the information you do know then read carefully to find out what you need to calculate. Set up the problem to solve for what you want to know. Check your answer to see if it is reasonable and in the correct units. Practice - Practice - Practice You must have this skill!

9. Dimensional Analysis • Use conversion factors to change the units • Conversion factors = 1 • 1 foot = 12 inches (equivalence statement) • 12 in=1= 1 ft. 1 ft. 12 in • 2 conversion factors • multiply by the one that will give you the correct units in your answer.

10. Examples • 11 yards = 2 rod • 40 rods = 1 furlong • 8 furlongs = 1 mile • The Kentucky Derby race is 1.25 miles. How long is the race in rods, furlongs, meters, and kilometers? • A marathon race is 26 miles, 385 yards. What is this distance in rods and kilometers?

11. Examples • Science fiction often uses nautical analogies to describe space travel. If the starship U.S.S. Enterprise is traveling at warp factor 1.71, what is its speed in knots? • Warp 1.71 = 5.00 times the speed of light • speed of light = 3.00 x 108 m/s • 1 knot = 2000 yd/h exactly

12. Examples • Because you never learned dimensional analysis, you have been working at a fast food restaurant for the past 35 years wrapping hamburgers. Each hour you wrap 184 hamburgers. You work 8 hours per day. You work 5 days a week. you get paid every 2 weeks with a salary of $840.34. How many hamburgers will you have to wrap to make your first one million dollars?

13. A senior was applying to college and wondered how many applications she needed to send. Her counselor explained that with the excellent grade she received in chemistry she would probably be accepted to one school out of every three to which she applied. She immediately realized that for each application she would have to write 3 essays, and each essay would require 2 hours work. Of course writing essays is no simple matter. For each hour of serious essay writing, she would need to expend 500 calories which she could derive from a slice of her mother's apple pies. Every three times she cleaned her bedroom, her mother would make her an apple pie with 8 slices. How many times would she have to clean her room in order to gain acceptance to 10 colleges?

14. 2.1Properties of Matter • Matter- anything that has mass and volume • Solid- holds a particular shape and has a definite volume • Liquid- does not hold its shape but has a definite volume • Gas- no definite shape or volume • Physical Property- characteristics of a substance that can be observed without altering the identity of the substance • Chemical Property- characteristics of a substance that cannot be observed without altering the identity of the substance • Physical Change- changes which do not alter the identity of a substance • Chemical Change- changes that do alter the identity of a substance • Law of Conservation of Matter- matter, like energy, can neither be created nor destroyed in any process.

15. 2.2 Mixtures • Mixture- blend of two or more pure substances that are not chemically combined • Heterogeneous Mixture- mixture in which particles are not uniformly intermingled and therefore have visibly different parts • Homogeneous Mixture- mixture made up of uniformly intermingled particles that therefore doesn’t contain visible different parts • Heterogeneous mixtures can be separated by filtration • Homogeneous mixtures can be separated by distillation, crystallization and chromatography

16. 2.3 Elements and Compounds • Element- substance that cannot be separated into simpler substances by chemical change • Compounds- substance that contains two or more elements chemically combined in a fixed proportion • Pure Substance- substance made of one kind of material with a unique set of chemical and physical properties. Includes both elements and compounds. • Chemical symbol – one or two letters only the first is capitalized • Periodic table – has the elements organized by families or groups (vertical columns) or periods (horizontal rows).

18. 2.4 Chemical Reactions • During a chemical reaction the identity of one or more substances changes. • Reactants to the left of the arrow become products on the right. Mg + Cl2 → MgCl2 • Possible Evidence of a Chemical reaction includes: temperature change, color change, production of a gas or precipitate (solid appears in a solution). • In all chemical reactions mass is conserved. What goes in must come out!

19. 3.1 Using and Expressing Measurements • Making Measurements • All Measurements are uncertain • Every measurement involves estimation • This uncertainty can be expressed as ± x where x is one tenth of the smallest measure possible with that instrument • Reliability in measurement • Precision - Repeatability of measurement • Accuracy - Nearness to accepted value

20. ? Precise Not Accurate Accuracy vs. Precision ? Accurate Not Precise ? Not Accurate or Precise ? Accurate And Precise

21. 3.1 Cont… • Significant Digits • Measurements are only as precise as the instrument • Numbers must be rounded to the correct number of significant figures • Atlantic Pacific Rule - If a decimal point is present count from the Pacific side starting with the first nonzero digit. If a decimal is absent count from the Atlantic side starting with the first nonzero digit

22. Rules for Significant Figures • All zeros between nonzero digits are significant (count them) • Zeros to the left of an expressed decimal and to the right of a nonzero digit are significant (count) • Zeros to the right of an expressed decimal and left of a nonzero digit are not significant (don’t count) • Zeros to the right of nonzero digits that are right of the decimal are significant (count them) • If there is no expressed decimal all zeros to the right of the last nonzero digit are not significant

23. Practice on Significant Figures 3000 1 3000 .00105 3 .00105 3.006 4 3.006 4020 4020 3 4020 .7000 4 .7000 80.007 5 80.007 2 .00091 .00091 2 50. 50.

24. 3.1 cont… II. Significant digits in Calculations A. When multiplying or dividing round to the least number of significant figures used in the operation Example: 2 X 12 = 24 round to 20 B. When adding and subtracting round to the fewest decimal places used Example: 3.02 + 5.3 + 1.158 = 9.478 round to 9.5 C. Conversions and exact numbers (counting numbers) have infinite significant digits Example .0432 km X 1000 m/km = 432 m D. If several operations are performed don’t round until the final answer E.If the last number is  5 Round up or < 5 round down III.Scientific Notation useful in working with very large or small numbers A. Make sure you can convert from and to scientific notation ( See worksheets and handout)

25. 3.1 cont… • Graphing • Label each axis with the variable and unit and give the graph a title • Independent variable goes on the X axis Dependent variable on the Y axis • Plot data points and connect with a best fit line (not dot to dot) • Use the finished graph to establish relationships (directly proportional, inverse, logarithmic) between the variables

26. 3.1 cont….. IV. Percents and Percent Error A. Be able to convert % to decimals & decimals to % B. Relative error (ER) is calculated by taking the observed value (O) minus the actual value (A) (this is absolute error (Ea) and dividing by the actual value (A) then multiplying by 100. C. Relative error is a measure of accuracy V. Ratios A. Ratios such as density and speed can be used to greatly simplify calculations

27. 3.2 Units of Measurement • The Metric System • International System of units – SI

28. Common Metric Prefixes

29. 3.2 Measurement Continued • Area and Volume Derived Units (combination of base units) • cm2 or m2 - area cm3 or m3 - volume 1dm3=1liter 1 cm3=1 ml B. Be careful converting between units

30. Some Derived Units

31. 3.2 cont…Temperature scales • Kelvin Scale-the SI scale used to measure temp. • Absolute Zero-the zero point on the Kelvin scale (-273°C) at which the motion of particles of matter ceases • Temperature is a measure of how hot or cold something is (average KE). How fast the particles move. • To convert from Celsius to Kelvin - °C=K-273 • To convert Kelvin to Celsius - K=°C+273 • Law of Conservation of Energy- in any process, energy is neither created nor destroyed. • The SI unit of energy is the joule 1 calorie=4.184 J • Heat and temperature are NOT the same thing!

32. 3.3 Solving Conversion Problems • Use dimensional analysis (factor labeling) to solve word problems • Conversion factors should be used to cancel the units you don’t want and leave behind the units you do want • Always list the information you do know then read carefully to find out what you need to calculate. Set up the problem to solve for what you want to know. Check your answer to see if it is reasonable and in the correct units. Practice - Practice - Practice You must have this skill!

33. Credits • Text – Pearson Chemistry • Microsoft Publishing Gallary • More Power to YA class