This document provides an overview of key concepts in chemistry. It discusses the differences between observations and inferences, and emphasizes recording observations rather than inferences in lab exercises. It also covers scientific methodology, including variables, controls, and the scientific method. Measurement concepts like accuracy, precision, error, and significant figures are defined. Formulas for calculating percent error are presented. Key terms like independent and dependent variables are introduced.

1. Chemistry
Chapter 1
IT’S ALL ABOUT THE PROCESS!!!

2. Observation vs. Inference
 Observation- What you pick up or perceive with your senses.
 Ex: you smell smoke.
 Inference- The conclusion you draw from what your senses
pick up.
 Ex: The smell of smoke tells you there must be a fire.

3. Note the Differences
In laboratory exercises, record observations
NOT inferences
Inferences may be used when writing the
conclusion in your lab report.
 Let’s test your observation skills…

5. Question 1
Are there cars parked on the sides of the road?

6. Question 2
What color is the pickup truck driving in the road?

7. Question 3
Any minivans around?

8. Question 4
What does the blue sign say?

9. Question 5
What's the speed limit?

10. Question 6
Are there any pedestrians on the road?

12. Answers
1. Yes
2. Blue
3. Yes
4. Yard Sale
5. 35 mph
6. No

14. Observation Activity #2
 Choose several people to be observers and choose two
people to be investigators.
 Allow the observers to look at the picture or this picture
for 30 seconds. The investigators should not look at the
picture.
 After 30 seconds, the investigators should begin
questioning the observers. Each Investigator should
question each observer. Then, the Investigators should
attempt to reconstruct the scene based on the
"eyewitness testimony".

16. Questions Asked
 How many cars were in the intersection?
Answer: 2
 Across the street, are there any parked cars on the side?
Yes
 Can you describe at least one of the cars driving through the intersection?
 Are there any other potential witnesses?
If they answer yes, ask the following question: What was this witness doing?
Where was he?
They should have noticed a person mowing a lawn across the street.
 What was the speed limit?
35
 Was there anyone parked in the first parking spot?
No

17. Observation vs Inference
 On the next slide, state whether the statement is an observation or an inference.

18. 1. There is a representation of a face on one side of the
coin.
2. The Latin word "Dei" means "God."
3. The coin was made by deeply religious people.
4. The date 1722 is printed on one side of the coin.
5. The coin was made in 1722.
6. The face on the coin is a representation of the
nation's president.

19. How many legs does the elephant
have?

20. What do you see?

21. Who is in this picture?
 Do you see former President Bill Clinton and Al Gore?
 Actually, it’s Clinton’s face twice with 2 different hair
cuts!

22. What do you see?
Hint:
There are
3 images.
1. An old lady
2. A young
woman
3. A man with
a big
brown
mustache

23. Take a very close look at the 2 vertical lines.
Is one line is longer than the other?
They are the SAME length!

24. Compare this picture to the next
one…

25. What’s the difference?

26. What do you see?

27. Can you build these shelves?

28. Does the square have
curved sides?

30. Read this sign

31. What do you see?

32. Can you stack these blocks?

33. What animal do you perceive?
A Duck, Bunny, or BOTH?

34. This image contains a
picture and a word.
Do you see both of
them?

36. Where are those dots coming from?!
Your
brain!

37. Look at the chart and say the color,
NOT the word
Your right brain tried to say the color,
but your left brain was reading the word.

38. Read across..

39. What images do you see?

40. Can you pick the tallest soldier?
They are all the same height!

41. What do you see?
The Landscape of Faces

42. Do you see the face on Earth?
How about now?

43. These circles are not moving, your brain is
making them appear to move. Try focusing on
one circle. It will stop moving.

44. Are these dots moving?

45. Does this image appear to be moving?
 It’s NOT!
 Just kidding, this one
is actually moving

46. Variables and Controls
 A variable is anything that can changed or tested in
an experiment.
 Independent variable: The variable being changed or
tested by the scientist.
Dependent variable: The variable being tested for or
determined by the independent variable.
 A valid experiment tests only one variable at a time.

47. The Scientific Method: A series of logical
steps to follow in order to solve problems.
 OBSERVE SOMETHING UNKNOWN OR NOT UNDERSTOOD.
 FORMULATE A QUESTION.
 FORM A HYPOTHESIS
 DESIGN AND CONDUCT AN EXPERIMENT
 MAKE OBSERVATIONS
 COLLECT AND ANAYZE DATA
 DRAW CONCLUSIONS
 FORMULATE A THEORY and RETEST AND PUBLISH

48. Making Measurements
measurements are made in this class using SI units.
LENGTH: distance between 2 points
VOLUME: space occupied.
MASS: the amount of matter in an object.
WEIGHT: the force with which gravity pulls on a
quantity of matter.

49. Scientific Notation:
 scientist use special notation to express VERY LARGE
or very small numbers.
 Ex: 300,000,000 m/sec = 3.0 X 108
 Ex: 1,007,000,000 sec = 1.007 X 109
 Ex: 0.000 000 000 004 76 m = 4.76 X 10-12

50. Accuracy, Precision, and Error
Accuracy
 1. The nearness of a
measurement to its accepted
value b. Systematic errors can
cause results to be precise but
not accurate
Precision
 The agreement between
numerical values of two or
more measurements that have
been made in the same way
 a. You can be precise without
being accurate

51. Calculating Percent Error (Relative
Error)
Percent error can have negative or positive
values
푃퐸푅퐶퐸푁푇 퐸푅푅푂푅 = 푉퐴퐿푈퐸 퐴퐶퐶퐸푃푇퐸퐷 − 푉퐴퐿푈퐸 퐸푋푃퐸푅퐼푀퐸푁푇퐴퐿
푉퐴퐿푈퐸 퐴퐶퐶퐸푃푇퐸퐷
X 100

52. Error in Measurement
1. Some error or uncertainty exists in all
measurement
a. no measurement is known to an infinite number of
decimal places
2. All measurements should include every digit
known with certainty plus the first digit that is
uncertain - these are the significant figures