# Chemistry

Introductory level chemistry notes

### Significant Figures

When recording a measurement, you cannot be more precise than the instrument, so a value is always comprised of all known digits plus one unknown.

- Digits 1 through 9 always count. (
**123**)
- Zeroes before digits do not count. (0.00
**123**)
- Zeroes in between digits do count. (
**1023** or **1.023**)
- Zeroes after a decimal point and after a digit do count. (0.00
**12300**)
- Zeroes after a digit in an integer value do not count. (
**123**000)

Multiplication / Division: Round answer to fewest sig figs.

Addition / Subtraction: Round answer to fewest decimal places.

### Metric Conversion Factors (x)

__Length__ (based on meter (m))
__Mass__ (based on gram (g))
__Volume__ (based on liter (L))

- 1,000 x = 1 kx
- 1 x = 10 dx
- 1 x = 100 cx or 1 * 10
^{2} cx
- 1 x = 1,000 mx or 1 * 10
^{3} mx
- 1 x = 1,000,000 ux or 1 * 10
^{6} ux
- 1 mL = 1 cm
^{3} (cc)

- 1 mile = 5280 feet
- 1 km = 1 mile
- 1.609 km = 1 mile
- 2.54 cm = 1 in (exact)
- 1 lb = 0.4536 kg = 454 g
- 1 qt = 946.4 mL

### Molecular Geometry

VSEPR Theory