MEASUREMENTS &

MAT

H

EXACT NUMBERS!Numbers determined by counting or by definition

Ex: 6 apples, 1 teacher1 inch=2.54 cm

IN SCIENCE…Numbers are based on

MEASUREMENTS made in the lab.

Our data is only as good as the measurements we make and the instruments we use.

QUALITATIVE DATAObservation that DOES NOT involve a number/measurement

EX. Presence of odor, color change

QUANTITATIVE DATAObservation that DOES involve a number/measurement (has magnitude size or amount)

Ex. Length, mass, volume

Accuracy: how close a measured value is to the actual (true) value.

Precision: how close the measured values are to each other.

COPY IN YOUR NOTES!!

ACCURACY VS. PRECISION

SIGNIFICANT FIGURES• Shows how PRECISE a

measurement is

• Indicates the QUALITY of the instrument you use (how sensitive or exact)

EX. Graduated cylinder vs. beaker

SIG FIG RULES!

COUNTING SIGNIFICANT FIGURES

5432.1

0.00032

4004

82.0000

10

5 sig figs

2 sig figs

4 sig figs

6 sig figs

SCIENTIFIC NOTATIONUsed to write really LARGE or really small #’s

Why? To save space & time

SCI. NOTATION RULES!Written in the form of m x

10n

m: ≥ 1 AND <10indicate the number of

sig. figs

STEPS OF THE SCIENTIFIC NOTATION

Step 1) Determine the sig figs106,000,000 = 3 sig figs

Step 2) Determine the value of M using the sig figs

1.06 (remember this must be between 1 and 10)

Step 3) Add the 10’s multiplier1.06 x 10n

Step 4) Determine the value of “n” by counting the number of times you move the decimal in the original number to get the value for “M”

Step 5) Determine the sign of “n” by looking at the direction that you moved the decimal

Move decimal to left = “n” is positiveMove decimal to right = “n” is negative

NOW GO THE OTHER WAY!!

Ex. 1) 7,801

Ex. 2) 0.00030

15

7.801 x 103

3.0 x 10-4

Ex. 1) 3.1 x 104

Ex. 2) 4.08 x 10-6

16

31,000

0.00000408

SI UNITS OF MEASUREMENTOne system for all scientists around the

world

We must have a standard for comparisonlength – meter (m)mass – kilogram(kg)time – second (s)volume – liter (L)

SI PREFIXESAdded to base units to represent large or smaller

quantitiesSI Prefix Unit Abbreviation Exponential Factorkilo K 103

hecto h 102

deka da 101

BASE m,g,s,L 100

deci d 10-1

centi c 10-2

milli m 10-3

King Henry Died By Drinking Chocolate Milk

EXAMPLE

10 g = ____________mg?

K h da b d c m

10,000

EXAMPLE

14.6 dL= __________ kL