1. Measurements and Calculations

2. Measurements are quantitative data that scientists obtain
“Measurements represent quantities” (Davis, Saquis, Frey and Saquis 33)
Quantity = “something that has magnitude, size, or amount” (Davis et al. 33)
Example: volume
“A quantity is not the same as a measurement” (Davis et al. 33)
Volume is a quantity
Teaspoon is a unit of measurement for volume
Measurements need a number and a unit!
Speed Limit = 50
Distance traveled = 5
Without units, the numbers don’t make sense

3. Le Système International d’Unités (SI)
Different standards used to be used to measure things
By having different standards for measuring things, data can be confusing
Scientists developed a list of common standards of measurements to be universal
This is called the SI system

4. Le Système International d’Unités (SI)
There are seven base units
Quantity
SI Unit
Abbreviation
Length
meter m
Time
second s
Mass
kilogram kg
Amount of Substance
mole
mol
Temperature
kelvin K
Electric Current
ampere A
Luminous intensity
candela cd

5. SI Units
“defined in terms of standards of measurement” (Davis et al. 33)
“The standards are objects or natural phenomena that are of constant value, easy to preserve and reproduce, and practical in size” (Davis et al. 33)

6. SI Base Units
Length
SI Base Unit = meter (m)
Can be measured using a meter stick
“A distance of 1 m is about the width of an average doorway” (Davis et al. 35)
The meter can be adjusted with prefixes
kilometer = 1000 meters
centimeter = 1/100 meter
Time = “interval between two occurrences” (“Chapter 1: Measurements and Calculations”)
SI Base Unit = second (s)

7. SI Base Units
Mass = “a measure of the quantity of matter” (Davis et al. 34)
SI Unit Name = kilogram (kg) (about the mass of a textbook (Davis et al. 35))
1 kg = 1000 grams
Smaller masses are typically measured in grams (1/1000 kg) or even smaller masses in milligrams (1/ kg)
Mass can be measured using an electronic or triple beam balance
Mass is not the same as weight!
Weight is the measure of the Earth’s gravitational pull on an object
Weight varies according to distance from Earth
The farther you are away from Earth, the less weight you have.
You will still have the same mass though!
Davis, Raymond E., Mickey Sarquis, Regina Frey, and Jerry L. Sarquis. Modern Chemistry. Austin: Holt, Rinehart and Winston, Print.

8. SI Base Units Amount of substance (Davis et al. 34) Temperature
SI Unit Name = mole (mol)
“the amount of substance of a system which contains as many elementary entities as there are atoms in kilogram of carbon-12” (Davis et al. 34)
Temperature
SI Unit Name = kelvin (K)
kelvin temperature = °C

9. SI Base Units
Electric current = “the time rate of flow of electric charge, in the direction that a positive moving charge would take and having magnitude equal to the quantity of charge per unit time” (“electric current”)
SI Unit Name = ampere (A)
Luminous Intensity = “a measure of the amount of light that a point source radiates in a given direction. It is expressed by the luminous flux leaving the source in that direction per unit of solid angle” (“luminous intensity”).
SI Unit Name = candela (cd)

10. Works Cited
“Chapter 1: Measurements and Calculations.” Course notes. Honors Chemistry Level 5. Department of Science, Serra Catholic. 30 September Davis, Raymond E., Mickey Sarquis, Regina Frey, and Jerry L. Sarquis. Modern Chemistry. Austin: Holt, Rinehart and Winston, Print. "electric current". Dictionary.com Unabridged. Random House, Inc. 4 Oct <Dictionary.comhttp:// "luminous intensity". Collins English Dictionary - Complete & Unabridged 10th Edition. HarperCollins Publishers. 4 Oct <Dictionary.com