1. Unit 1 Intro to Chemistry and Measurement Chemistry I Mr. Patel SWHS

2. Topic Outline Learn Major Elements and Symbols Intro to Chemistry (1.1, 1.2) Significant Figures (3.1) Measurement (3.1, 3.2) Factor-Label Method of Conversions (3.3)

3. Intro to Chemistry Matter – anything that has mass and occupies space Chemistry – study of the composition of matter and the changes it undergoes

4. Intro to Chemistry Chemistry affects all aspects of life and other natural events! – Food Digestion – Leaves changing colors – Muscle contraction – Driving cars

5. Intro to Chemistry Five different areas or branches of chemistry

6. Organic Chemistry Study of all chemicals containing carbon

7. Inorganic Chemistry Study of chemicals that do not contain carbon

8. Biochemistry Study of processes that occur in living things

9. Analytical Chemistry Study that focuses on the composition of matter

10. Physical Chemistry Area that deals with the rate, mechanism, and energy transfer of chemistry

11. Types of Research Pure Chemistry – increase chemical knowledge Applied Chemistry – goal oriented

12. History of Chemistry Alchemy - change other metals to gold Lavoisier – Father of Modern Chemistry – Observation to measurement

13. Scientific Method

14. Significant Figures Sometimes we estimate numbers – If we measure between 9.8 and 9.9, we may say it is 9.85. – We know that the 9 and 8 are definite; 5 is estimated. Discuss accuracy/precision later Significant Figures – the digits from a measurement that are known precisely plus an estimated digit

15. Rules for Counting Significant Figures 1.Every nonzero number is significant (sig.) – 1453 = 4 sig fig 2.Zeros between nonzero numbers are sig. – 300205 = 6 sig fig 3.Leftmost zeros in front of nonzeros are NOT sig. (placeholders) – 0.000356 = 3 sig fig 4.Zeros at end of a number are significant if there is a decimal point – 900.00 = 5 sig fig 5.Zeros at the end of a number are NOT significant if there is NOT a decimal point – 900 = 1 sig fig 6.Counting numbers and exact numbers have an infinite number of sig. figures – 23 people = infinite

16. Significant Figure – My Way Just think about the Atlantic and Pacific Oceans in relation to the USA Is the decimal point Absent (Atlantic) or Present (Pacific) Choose direction: Start at that “ocean” and come toward the USA (number) Stop at first NONZERO number Count that number and everything after

17. Sig Fig Practice 5005 63.207 9050 3.00 0.00509 0.00003 7000 4 sig fig 5 sig fig 3 sig fig 1 sig fig

18. Calculations with Sig. Fig. When ROUNDING, choose the number of sig figs needed. Look at the number to the right of last sig fig to determine if you need to round. Special rules for adding/subtracting and multiplying/dividing

19. Adding/Subtracting Sig Fig Answer to addition or subtraction problem should contain the same number of decimal places (not sig fig) as original number with the least decimal places. Ex: 12.52 + 349.0 + 8.24 – Sum is 369.76 – But 349.0 has only ONE decimal place – ANSWER is 369.8

20. Sig Fig Add/Subtract Practice 61.2 + 9.35 + 8.6 9.44 – 2.11 1.36 + 10.17 34.61 – 17.3 14.2 + 8.73 + 0.912 79.2 7.33 11.53 17.3 23.8

21. Multiply/Divide Sig Fig Answer to multiplication or division problem should contain the same number of significant figures as original number with the least significant figures. Ex: 7.55 x 0.34 – Product is 2.567 – But 0.34 has only TWO sig figs – ANSWER is 2.6

22. Sig Fig Multiply/Divide Practice 2.10 x 0.70 2.4526 / 8.4 8.3 x 2.22 8432 / 12.5 22.4 x 11.3 x 5.2 1.5 0.29 18 675 1300

23. Measurement Measurement – quantity with a number and unit Accuracy – how close you are to the true value Precision – how close your measurements are to one another

25. Scientific Notation Used for very large or very small numbers Converts a single number to a product of two numbers – Ex: 8000  8 x 10 3 – Ex: 0.234  2.34 x 10 -1

26. Scientific Notation Practice 1.252 2.125000 3.0.00305 4.0.00000000548 1.2.52 x 10 2 2.1.25 x 10 5 3.3.05 x 10 -3 4.5.48 x 10 -9

27. International System of Units (SI) Five SI base units: – meter (length) – kilogram (mass) – Kelvin (temperature) – Second (time) – Mole (amount)

28. Metric Conversions Kilo -k10 3 1000 BASE10 0 1 Deci -d10 -1 0.1 Centi -c10 -2 0.01 Milli -m10 -3 0.001

29. Factor-Label Method Write down starting and ending unit Write all relevant conversion factors Cancel units to get to end unit – To cancel a unit, the unit must be on the top and bottom

30. Conversion Examples