1. unit Measurement number 42.5 g 1.05 mL 16 cm measurement:
quantity with _______ and a _____.
42.5 g mL 16 cm
number
unit

2. Scientific Notation a really big number: 100,000,000,000,000
(atoms in a cell)
or really small number: meter
(size of one atom)
can be written without zeroes
by using powers of 10.
Expressing very large numbers, such as the estimated number of stars in a galaxy, is easier if scientific notation is used. Do some on the board as examples of moving decimal back and forth (10 min)

3. Scientific Notation 100,000,000,000,000 = 1 x 1014 atoms
(atoms in a cell)
meter = 1 x 10–11 meters
(size of an atom)
Expressing very large numbers, such as the estimated number of stars in a galaxy, is easier if scientific notation is used. Do some on the board as examples of moving decimal back and forth (10 min)

4. Accurate and Precise but not Neither Precise Nor Accurate _______
Yes good acc poor prec is possible with average
Accurate
and
Precise
but not
Neither Precise
Nor
Accurate
_______
Precise
________
Accurate

5. Accuracy, Precision, and % Error Accuracy: Precision:
how close to the actual or true value
Precision:
how close to each other (repeatable)

6. Accuracy, Precision, and % Error
Error = exp - acc
Error
% Error = ________ x 100
acc
|exp – acc|
exp – experimental value
acc – accepted value

7. % Error Calculation:
What is the % error if a measurement of 99.1oC is made, but the true temperature is 100.0oC?
(Is being off by 9 cm a lot or a little? It depends on whether you
are measuring the length of a piece of paper or the distance to here to Philly for the X Games.

8. Quick Quiz!
1. Which of the following expressions has NOT been correctly changed to sci. not.?
=  10–3
=  10–5
8,426,000 =  106
45, =  103
Scientific notation change both numbers to standard and compare (Do these on board)

9. Quick Quiz.
2. Which set of measurements of a 2.00-g object is the most precise?
2.00 g, 2.13 g, 1.92 g
2.10 g, 2.00 g, 2.20 g
2.05 g, 2.04 g, 2.05 g
1.50 g, 2.00 g, 2.50 g