1. Welcome to Intro to Chemistry! Chem 100
Mrs. Sedlock

2. Attendance
Introduction
Syllabus
Scientific Math

3. Introduction….
A little about me…..
What about you?
The course…..

4. The course See syllabus for information pertaining to the course
Contact information

5. Why Chemistry?
Study of matter- everything around you!

13. What can I do with A Degree in chemistry?
Analytical- focused on the composition of matter
Research, development, forensics, environmental
NASA, textile, petroleum, food, electronics, glass, paper, packaging, cosmetics, paint, drug, chemical industries

14. Biochemistry- the study of chemical rxn that take place in organisms
Research, development, analysis, consulting, quality control, medical, environmental
Research labs, pharmaceutical, biotech firms, food processors, industrial inspection agencies, colleges, CDC

15. Organic- study of compounds containing carbon
Research, development, analysis, quality control, consulting
Petroleum, coal wood plastics industries
Manufacturers of synthetic materials
Research
Federal and state government
College and universities

16. Physical Chemistry- apply physics and math to problems that interest chemists, biologists and engineers
Plastics
Ceramics
Materials
science
Nanoscale
Chemical biology
Computer molecular modeling

17. Business- Sales/marketing, management, banking/finance, advertising
Or Maybe a Minor in Chem?
Business-
Sales/marketing, management, banking/finance, advertising
Manufacturing firms, drug stores, medical/pharmaceutical supply companies, industries-glass, paper, plastic, petroleum, etc, agricultural product companies, environmental management

18. Art
Scientific Illustration

19. Law Patent agents, patent attorneys, legislator
Manufacturing firms, law firms, private practice, environmental agencies

20. Chemistry is the Central Science
Physical
chemistry
Organic
Analytical
Forensic
Geology
Biochemistry
Medicinal

21. Evolution of Chemistry
Chinese- Yin and Yang
Greek philosophers-Earth, Air, Fire, and Water
Aristotle
Antoine Lavoisier – quantitative chemistry

22. Plan- an experiment to evaluate nature
Scientific Method
Plan- an experiment to evaluate nature
Observe – an experiment and collect data
Explain – the data by forming a hypothesis

23. Hypothesis
Hypothesis is a proposal that explains the results of one or more experiments. It may be
Confirmed
Rejected
Revised
Based on new experiments that test the
hypothesis

24. Natural Law is a confirmed hypothesis
has a mathematical relationship to describe the results
Explain many observations
Do not have scientific data to prove them wrong

25. Scientific Theory Confirmed hypothesis
DOES NOT have a mathematical relationship that describes the results
Explain many observations
Ex: theory of evolution

26. Scientific Measurement
Every measurement has a number and a unit and an uncertainty
Ex: driving 65 mph
65 is the number, the unit is mph, ± 1 mph is the uncertainty

27. Uncertainty and Significant Figures
All measurements must be reported with the correct number of significant figures in order to calculate the answer.
“Sig-Figs” include all the digits known plus the last digit that is estimated
Ex.
You use the scale in the produce section of the store to get an approximate weight of your vegetables. The scale is calibrated in 0.1lb intervals Your vegetables are between 2.4 and 2.5lbs.so you estimate its weight to be 2.46lbs.
Your answer has three significant figures

28. Rules to determine number of significant figures
1. All non-zero numbers are always significant
2. Zeros are tricky…..
Leading zeros- NEVER significant (0.005)
Captive zeros- ALWAYS significant (505)
Trailing zeros- SOMETIMES….
(decimal-YES otherwise no)
5.000 (yes) 5,000 (no)

29. Example 24.7 meters, 7.43 meter and 714 meters
-all have three significant figures, all non-zero digits

30. Example 7003 meters 40.79 meters 1.503 meters -all have trapped zeros
-all have four significant figures

31. Example 300m has 1 “sig-fig” 7000m – has 1 “sig-fig”
27,210m – has 4 “sig-figs”

32. Example
There are two situations when you have an unlimited number of “sig-figs”.
1. Counting – Ex. 23 people in the classroom
2. Using exactly defined quantities.
Ex. 60min. = 1 hour
500 pages = 1 ream

33. How many “Sig-figs” are there?
40,506mm =
x 104 m =
22 meter sticks =
m =
98,000 m =
(3)
(5)
(5)
(unlimited)
(4)
(2)

34. Rounding
Keep all digits until the final calculation and round the final answer!
Count the number of sig figs starting from the left
Then look to the number to the right of that digit – if its less than 5 leave your last digit and drop everything to the right
If it’s more than 5, round your number up one digit and drop everything to the right

35. Rounding Problems = 3.147 x 102 = 1.8 x10-3 = 8.8 x 103
Round each measurement to the number of “sig-figs” shown in parentheses. Write answers in scientific notation first !!!!
meters (four)
meters (two)
8792 meters (two)
= x 102
= 1.8 x10-3
= 8.8 x 103

36. Using “Sig-Figs” when Calculating
A calculated answer can not be more precise than the least precise measurement used in the calculation
For multiplication and division use least # of sig-figs in measurements you are multiplying or dividing

37. Using “Sig-Figs” when Calculating
For addition and subtraction use least number of decimal places in measurements you are adding or subtracting

38. Example Try this: 6.9cm x 0.0876cm Perform operation (multiply)
Put in scientific notation
Round to correct number of significant figures

39. Example
5 g
5.0 g g
15.00 g

40. Precision and Accuracy
Accuracy- how close the measurement is to accepted value
Precision- how close a series of measurements are to each other.

42. Lisa Lamont Leigh Weighing 1 47.03 47.34 47.95 Weighing 2 47.94 47.39
Three students made multiple weighings of a copper cylinder, each using a different balance. Describe the accuracy and precision of each student’s measurements if the correct mass of the cylinder is 47.32g
Lisa
Lamont
Leigh
Weighing 1
47.03
47.34
47.95
Weighing 2
47.94
47.39
47.91
Weighing 3
46.83
47.31
47.90
Weighing 4
47.47
47.33
47.93
Inaccurate & imprecise
Accurate & precise
Inaccurate & precise

43. “Calibrating” an instrument improves it’s accuracy

44. Unit Analysis A ratio of equivalent measurements Ex.
1 dollar = 4 quarters = 10 dimes = 100 pennies
1 dollar = 4 quarters
4 quarters dollar

45. Unit analysis
A way to solve problems using units, dimensions or measurements
Start with known, work toward unit you want
Ex. How many seconds in 8 hours?

46. Converting Metric Units to Metric units (2 step-process)
Go from “known” to a basic unit, then basic unit to unit you want.
236.6 kg = __________cg

47. Writing answers correctly
Must be in scientific notation
Must have correct number of significant figures.
Don’t count the sig-figs in conversion factors
Count sig-figs in “known” and put the answer in the same number of sig-figs.

48. Scientific Notation Write down the significant digits
Then move the decimal point to the right of the first nonzero digit
Use the power of t3n to indicate the number of places you moved the decimal
Negative if moved to the right
Positive if moved to the left

49. Scientific notation Examples
_________________
189, _________________
_________________
3,570,000,000 _________________

50. Scientific notation examples
3.7 x 10 1 ________________ x 10-3 ________________ 2.7 x 10 5 ________________ 6.83 x ________________ 4.5 x 10 3 ________________

51. Using scientific notation
6.40 x  x 10 15
3.20 x 1017
6.5 x x x 10 8
2.1 x 1016
5.75 x  x 10 8
7.93 x 107
1.80 x x x 10 4
6.48 x 108