Unit 3
Scientific Measurement
Types of Measurement
• Qualitative
– Gives results in nonnumeric, descriptive form.
• Example: looking at a picture and evaluating if it’s a
good picture or not.
• Quantitative
– Gives results in a definite form, usually in
numbers.
• Example: looking at a picture and recording the exact
number of people, number of different kinds of
animals, etc.
Accuracy - v - Precision
• Accuracy = “closeness” to the standard or exact
value.
• Precision = “closeness” to the standard or exact
value of several measurements.
*accuracy is the value of the measurement in terms of
good or bad whereas precision is how consistent
(reproducible) the measurement is.
example: kicking field goals
accuracy = kicking the ball between the uprights.
precision = kicking the ball between the uprights and
each kick travels the same path.**precision depends
on more than one measurement**
Scientific Notation
• Chemistry involves very small and very large
numbers.
– Example: 1 gram of Hydrogen =
301,000,000,000,000,000,000,000 hydrogen
molecules. This is a long number to write.
• Use scientific notation:
– 36,000 is written 3.6 x 104 (3.6 x 10 x 10 x 10 x 10)
• If it’s a small number such as .00036 use scientific
notation:
– .00036 is written 3.6 x 10-4
Multiplication/Division/Addition/Subtraction
• Mathematics Review (pg. 31)
Significant Figures
• = include all the digits that are known
precisely plus one last digit that is estimated.
– Write down 1-6 on pg. 33 in your book
– Do pg. 34, #7 a-f