1. Chemistry, Matter and MeasurementsL

2. What is Chemistry? AKA the central science
The study of matter and the changes that it undergoes
Used in everything!

3. What’s it matter? Matter – anything that has mass and volume
Mass – amount of matter
Volume – space it takes up
DON’T confuse mass with weight
Weight – gravitational pull on a mass
If I put you on the moon you weight less, however you have the same mass
If I cut your arm off you have less mass and weight……(and blood pressure)

4. Macro vs Micro
Much of what happens in chemistry is on the macroscopic level
What you can see, touch, smell etc.
However , a lot happens on the submicroscopic level
To be seen we must make models
Model – a visual, verbal or mathematical explanation of data (turning Micro  Macro)

5. Big ones for Chem. Base Units Use international system of units (SI)
Manipulated by
powers of 10
ame
Symbol
Distance
meter m
Mass
kilogram kg
Time
second s
Electrical current
ampere A
Temperature
kelvin K
Amount of a substance
mole
mol
lumination
candela cd
Big ones for Chem.

6. Derived Units Taken by manipulating base units
Volume – space an object occupies
L (m) x W (m) x H (m)
Therefore, volume = m3
10 cm3 = 1 Liter (L)
Typical units:
Liters
cm3

7. Derived Units (continued)
Density
Amount of mass packed into a volume
Density = Mass over volume (D = M/V)
Typical units are g/cm3

8. More or less

9. What’s Scientific Notation?
My brain is on fire with the crazy amount of info here

10. Rules of Sci. Not. Always between 1 and 10 and ten raised to a power.
The power tells you how may times to multiply the 1st number by 10.
Ex:
1.12 x 105 = 112,000
x 102 =
works the same in the opposite direction.
4.5 x 10-4 =
x =

11. Adding/Subtracting Sci. Not.
Get all exponents to the same value, then add/subtract the first number.
Ex:
5 x 10-5m + 2 x 10-5m
1.26 x 104kg x 103kg
4.39 x 105kg – 2.8 x 104kg

12. Multiplying/dividing Sci. Not.
1st multiply/divide the first number
2nd add (multiplication)/subtract (division) the second number
Ex:
(9 x 108)/(3 x 10-4) = (9/3) x 10(8 - -4)
(2 x 103) x (3 x 102) = (2 x 3) x 10(3 + 2)

13. Practice
Pg 32 14a-h
Pg33 15a-d, 16a-d

14. Significant figures Include all known digits plus one estimated digit
Rules
Rule
Ex.
Sig Fig.
Non-zero numbers are always significant
72.3 3 6
Zeros between non-zero numbers are always significant
50.001
17.02 5 4
All final zeros to the right of the decimal place are significant
6.20
9.0 2
Zeros that act as placeholders are not significant. Convert to Scientific notation to remove the placeholder zeros.
0.0253
20000
4320 1
Counting numbers and defined constants have an infinite number of sig. fig.
6 mol.
60 s = 1 min ∞

15. Measurement Reliability
Accuracy – how close a value is to an accepted value
Precision – how close a series of measurements are to one another.

16. Ex: g/cm3 Student A Student B Student C Trail 1 1.54 1.40 1.70 Trial 2
Students were asked to find the density of an unknown powder.
The powder was table sugar which has a density of 1.59g/cm3
g/cm3
Student A
Student B
Student C
Trail 1
1.54
1.40
1.70
Trial 2
1.60
1.68
1.69
Trail 3
1.57
1.51
1.71
Average
1.53
Which student was most precise?
Which student was most accurate?

17. Percent Error
Error -- Difference between experimental and accepted values
Percent error = (expected - actual)/accepted value x 100

18. Ex: Find the % error for student A trial 1 g/cm3 Student A Student B
Student C
Trail 1
1.54
1.40
1.70
Trial 2
1.60
1.68
1.69
Trail 3
1.57
1.51
1.71
Average
1.53
Ex:
Find the % error for student A trial 1
Error
g/cm3
Student A
Student B
Student C
Trail 1
0.05
0.19
-0.11
Trial 2
-0.01
-0.09
-0.10
Trail 3
0.02
0.08
-0.12