1. Chemistry is the study of matter and how it reacts.
What is Chemistry?
matter
The “stuff” in the universe is made
of “building blocks” formed in stars.
atoms/elements
Chemistry is the study of matter and how it reacts.
To study matter and its reactions, we’re going to need to make a lot of measurements…
To study matter, we’ll need to make a lot of measurements…

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

3. 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)

4. 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)

5. 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

6. Accuracy, Precision, and % Error Accurate: Precise: (repeatable)
close to the accepted or true value
Precise: (repeatable)
close to each other
(if only last digit varies)

7. Accuracy, Precision, and % Error
% Error = (________) x 100
acc
exp – acc
exp – experimental value
acc – accepted value

8. % 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.

9. Quick Quiz!
1. What is one reason to study chemistry?
to pass the test
you need it before driver’s ed
to be the coolest kid in school
to explain the natural world around you

10. Quick Quiz.
2. 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)

11. Quick Quiz.
3. 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