Transcript Significant Figures

Significant Figures
8/15/13
Bellwork (8/15/13)
 What is a Domino?
 It is a method for converting a unit of
measurement into another unit of
measurement
Significant Figures
 Significant Figures (sig. figs.): the number of
digits that carry meaning contributing to the
precision of a measurement or calculated
data.
Important Note!!!
 In-class notes are ONLY slides 14, 17,
18 and 19!
Precision and Accuracy
Low Accuracy
High Precision
High Accuracy
Low Precision
High Accuracy
High Precision
Significant Figures
 Significant figures, which are also called
significant digits, are very important in
science.
 Each recorded measurement has a certain
number of significant figures.
 Calculations done on these measurements
must follow the rules for significant figures.
Significant Figures
 The significance of a digit has to do with
whether it represents a true measurement or
not.
 Any digit that is actually measured or
estimated will be considered significant.
 Placeholders, or digits that have not been
measured or estimated, are not considered
significant.
Significant Figures
 There are 5 rules to determine which zeros in
a number are significant or not.
Rules for Significant Figures
 Rule #1: All non-zero digits (1-9) are
significant.
For example:
453
number of sig figs______
345.21 number of sig figs______
Rules for Significant Figures
 Rule #2: Zeros between non-zero digits are
significant.
For example:
12.007
number of sig figs______
3008007
number of sig figs______
Rules for Significant Figures
 Rule #3: Zeros to the left of the first non-
zero digit are NOT significant.
For example:
1.02
0.12
0.00127
0.00040301
number of sig figs______
number of sig figs______
number of sig figs______
number of sig figs______
Rules for Significant Figures
 Rule #4: If a number ends in zeros to the
right of the decimal point, those zeros are
significant.
For example:
 2
number of sig figs______
2.0
number of sig figs______
2.00
number of sig figs______
2.000
number of sig figs______
{This signifies greater precision.}
Rules for Significant Figures
 Rule #5: If a number ends in zeros, the zeros
to the right are NOT significant IF there is NO
decimal point present.
For example:
47100
number of sig figs______
20060
number of sig figs______
40000
number of sig figs______
The Atlantic - Pacific Rule
for Significant Figures
 When determining the number of significant
figures ask the question:
 “Does the number have a decimal point?”
(YES or NO answer)
 If YES, then think of “P” for Present and the
Pacific ocean
 If NO, then think of “A” for Absent and the
Atlantic ocean
The Atlantic and Pacific Rule
for Significant Figures
The Atlantic and Pacific Rule
for Significant Figures
 "P" for "Present". This means that we imagine an
arrow coming in from the Pacific ocean, from the
left side
 "A" for "Absent". This means that we imagine an
arrow coming in from the Atlantic ocean, the right
side.
The Atlantic and Pacific Rule
for Significant Figures
 Look for the first non zero number starting
from that direction
 That number, and all other numbers following
it are considered to be significant
 For “P” the numbers to the right of the first
non zero number
 For “A” the numbers to the left of the first
non zero number
Sig. Figs. Practice
Ex 1) 0.020110
Ex 2) 730800
 1) 48001
 2) 9807000
 3) 0.008401
 4) 40.500
 5) 64000
 6) 64000.
 7) 64000.00
 8) 0.0107050
Sig. Figs. Practice
Ex 1) 0.020110
Ex 2) 730800
 1) 48001
 2) 9807000
 3) 0.008401
 4) 40.500
 5) 64000
 6) 64000.
 7) 64000.00
 8) 0.0107050
Ex 1) 0.020110 (5 sig. figs.)
Ex 2) 730800 (4 sig. figs)
 1) 48001 (5 sig. figs.)
 2) 9807000 (4 sig. figs.)
 3) 0.008401 (4 sig. figs.)
 4) 40.500 (5 sig. figs.)
 5) 64000 (2 sig. figs.)
 6) 64000. (5 sig. figs.)
 7) 64000.00 (7 sig. figs.)
 8) 0.0107050 (6 sig. figs.)