1. SI Base Units

2. SI Base Units Length Meter (m) Time Second (s) Mass Gram (g) Current
Ampere (A or amp)
Temperature
Kelvin (K)
Luminous Intensity
Candela (Cd)
Amount of Substance
Mole (mol)

3. Prefixes to Memorize .

4. femto f
10-15
pico p
10-12
nano n
10-9
micro
10-6
milli m
10-3
centi c
10-2
deci d
10-1
BASE UNITS
deka
da (or dk)
101
hecto h
102
kilo k
103
mega M
106
giga G
109
tera T
1012

5. Significant Digits Significant Figures

6. You may be asked to round to 3 significant figures ( or possibly 4 or 5)
But first you must know how to determine whether a number is considered significant

7. Rule 1 1. All digits 1-9 are significant 789 12587 1.234 3 sig figs

8. Rule 2 ~ BETWEEN
Any zero between two significant digits is automatically significant
1003
4 sig figs
10.03
1,000,007
7 sig figs

9. Rule 3 ~ FINAL ZERO
Any FINAL ZERO (after the decimal point) is significant.
12.30
4 sig figs
8 sig figs
4.0
2 sig figs

10. Rule 4 ~ placeholder
Any zero is insignificant if it is not between two sig digits nor the final zero after a decimal point. Theses zeros are called placeholders.
2 sig figs
3 sig figs
400
1 sig fig
10000
789,600
4 sig figs

11. Examples
30040 grams
4 sig figs
The last zero is not significant

12. 0.663 kg
3 sig figs
The zero only located the decimal point and is not significant

13. 20.05 L
4 sig figs

14. 1500 mg
4 sig figs
There is line over the final zero, so all digits are significant

15. grams
1 sig fig
The zeros are only place holders. They are not significant

16. The End
Let’s practice!