1. Lesson 1 – SI Units and Dimensional Analysis
MATH and Methods
Lesson 1 – SI Units and Dimensional Analysis

2. Introduction to Chemistry (not in notes)
Chemistry: The Central Science
Chemistry is the science that investigates and explains the structure and properties of matter.
Seeks to explain the submicroscopic events that lead to macroscopic observations

3. Branches of Chemistry (not in notes)
Area of Emphasis
Examples
Organic chemistry
most carbon-containing chemicals
pharmaceuticals, plastics
Inorganic chemistry
(this class)
in general, matter that does not contain carbon
minerals, metals and nonmetals, semi-conductors
Physical chemistry
the behavior and changes of matter and the related energy changes
reaction rates, reaction mechanisms
Analytical chemistry
components and composition of substances
food nutrients, quality control
Biochemistry
matter and processes of living organisms
metabolism, fermentation

4. SI Units (Le Systéme Internationale)
Units of measurement
SI Units (Le Systéme Internationale)
Scientists need to report data that can be reproduced by other scientists. They need standard units of measurement.
Standard Units
A standard unit is a defined unit in a system of measurement
There are seven standard units in SI. Le 4

5. SI Units Official definitions of the seven base units 5

6. Derived units of measurement
A derived unit is any unit based off one or more SI units
In other words:
a derived unit is a created unit as opposed to a natural occurrence
The main derived units used in this class are volume and density.

7. Volume Volume = the amount of space occupied by a substance
Volume can be found mathematically
(Vrect. prism= L*W*H)
Volume can also be measured by
water displacement
By definition 1 cm3 = 1 mL

8. Density Density = amount of mass per unit of volume
D=m/v
Units for mass are grams
Units for volume can either be mL or cm3
Remember 1ml = 1 cm3
Many known densities are listed in your reference packet, these will be useful throughout the semester.

9. BASE UNIT (gram, liter, meter)
Prefix
Symbol
Factor
Scientific Notation
giga G
109
mega M
106
kilo k
1000
103
hecto h
100
102
deka da 10
101
NO prefix, use
BASE UNIT (gram, liter, meter) 1
deci d
1/10
10-1
centi c
1/100
10-2
milli m
1/1 000
10-3
micro μ 1/
10-6
nano n 1/
10-9
pico p 1/
10-12

10. Why do we use the metric system?
Advantages
Simple to use
Easy to convert from one unit to another
Dimensional Analysis (coming soon!)
Universal – used worldwide
By all scientists to communicate
By all industrialized nations
Except United States

11. Unit Equalities – Some examples
1 meter = 1000 mm
1L = 1000 mL
1 km = 1000 m
1 mole = x 10²³ particles (e.g. atoms, molecules, ions, etc.)
1 kg = 1000 g
1 day = 24 hours
All unit equalities can be turned into conversion factors.

12. Dimensional Analysis Process for converting between units.
The Unit Equality (1 km = 1000 m) becomes the Conversion Factor:
1 km or m
1000 m km
This is a technique for converting units.
95% of all your problems in this class will be of this type.

13. Using Dimensional Analysis
Multiply the starting unit by the conversion factor.
Example: Convert 4.6 m to km
4.6 m x 1 km = km
1000 m
If you use your conversion factors properly, the units you started with should cancel

14. Examples
Convert between the following measurements using dimensional analysis (show your conversion factors):
1.) mg x ___________ = g
2.) mol x ________________= atoms
3.) 1,098 mL x _________ = L
4.) 5 km x _______ x ________ = cm
1 g
1000 mg
6.022 x 1023 atoms
5.9 x 1023
1 mol
1 L
1.098
1000 mL
1000 m
100 cm
500,000
1 km
1 m

15. Multiple Unit Dimensional Analysis
Convert 455 km/hr to m/s
Convert 6.67 g/mL to mg/L
Convert 45.0 m/s to mm/hr
455 km/hr x 1000 m/1 km x 1 hr/60 min x 1 min/60 s
= 126 m/s
6.67 g/mL x 1000 mg/1 g x 1000 mL/1 L
= 6,670,000 mg/L
45.0 m/s x 1000 mm/1 m x 60 s/1 min x 60 min/1 hr
= 162,000,000 mm/hr

16. (Honors) Converting Cubed Units
Express 4563 mm³ in m³
Express 35.6 mol/m³ in atoms/cm³
4563 mm3 x (1m/1000 mm)3 = x 10-6 m3
35.6 mol/m3 x x 1023 atoms/mol x (1m/100 cm)3
= 2.14 x 1019 atoms/cm3