## We introduced the seven Base SI units: mass, length, time, temperature, amount of substance, electric current and luminous intensity. In CHEM 1314 we are interested in the first five of these base units; mass, length, time, temperature, amount of substance. You must know these usints and their symbols.

## We then discussed the derived units important to our class this semester; volume, area, temperature (degrees Celsius), temperature (degrees Fahrenheit), heat, pressure and density. Again you are responsible for these units and their symbols.

## Everyone is responsible for memorizing the prefixes used with the metric units. The most important are giga, mega, kilo, centi, milli, micro, nano, pico and femto.

## Everyone is also responsible for the following English relationships;

## 12 in = 1 foot## 3 feet = 1 yard## 5280 ft = 1 mile |
## 4 quarts = 1 gallon## 2 pints = 1 quart |
## 16 ounces = 1 pound## 2000 lbs = 1 ton |

## We looked at an animation to explain the difference between precision and accuracy.

## Accuracy means the the agreement of a particular value with the true value.

## Precision is the agreement between several measurments of the same quantity.

## We looked at an animation demonstrating the relationship between measurement and significant figures.

## We listed the rules for assigning significant figures and did several examples. Then we started to discuss how to handle significant figures when doing calculations. Because the browser crashed I was not able to show a few 'simple' examples of how to determine the correct number of significant figures in calculations. So I made an example up off the top of my head. It turned out to be more challenging than I had planned. I apologize for that.

## Here is the problem we did at the end of class. Look it over and we'll review a few more examples on Monday.