Chapter 1 Flashcards
Chemistry
The field of study that deals with the composition, properties, and changes of matter
Matter
- Any physical entity that you can see, feel, taste and smell
- Any physical entity that has mass and volume
Scientific method
- Observation
- hypothesis
- experiments
- theory
Which measurement systems are used most in the world?
Metric system and international system (SI)
How do we make a stating measurement more convenient?
By using scientific notation and unit prefrences
prefix
•what does it do when it is placed in front of a unit
•what does it do
•example
- it increases or decreases the size of that unit
- it makes units smaller or larger than the initial unit by one or more factors of 10 and indicates a numerical value
- 1 kilometer = 1000 meters
prefixes that increase the size of the unit
•4
- tera = 10^12
- giga = 10^9
- mega = 10^6
- kilo = 1000
prefixes that decrease the size of the unit
•7
- deci = 10^-1
- centi = 10^-2
- milli = 10^-3
- micro = 10^-6
- nano = 10^-9
- pico = 10^-12
- femto= 10^ -15
Accurate measurements
the measurement is correct
Precise measurements
the measurement is repeatable
Exact numbers
Obtained by counting items or from a definition that compares two units in the same measuring system
Measured numbers
Everything else for which we must us significant figure rules
A number is a significant figure if it is…
• 4 things
- Not a zero
- a zero between nonzero digits
- a zero at the end of a decimal number
- any digit in the coefficient of a number written in scientific notation
A zero is not significant if it is…
• 2 things
- at the beginning of a decimal number
2. used as a place holder in a large number without a decimal point
Sig Fig Rules: What do you do when multiplying/dividing?
For your answer, use the same number of SFs ad the number with the fewest SFs
Sig Fig Rules: What did you do when adding/subtracting
For your answer, use the same number of decimal places as the measurement with the fewest decimal places
Equalities
•what does it allow
•what does it state
•how can it be written
- allows us to convert between units
- states the same measurement in two different units
- can be written using the relationships between two metric units
1kg= __g
1000g
1g= __mg
1000mg
1mg= __g
0.001g
1mg= __ug
1000ug
Conversion factor
•what is it the key to
•what is it and how is it obtained
•how can it be inverted
- the key to dimensional analysis
- a fraction obtained from an equality
- can be inverted to give two conversion factors for every equality
Percent factor
•what is it made from
•what is it (4 points)
- a conversion factor made from a percent
- gives the ratio of the parts to the whole ( %=(parts/whole) x 100%)
- uses the same units for the parts and whole
- uses the value 100
- can be written as two factors
- ppm
* ppb
- parts per million (10^6)
* parts per billion (10^9)
Density
- compares the mass of an object to its volume
* mass/volume
Why does ice float?
Because the density of ice is less that the density of water
Why does aluminum sink in water?
Because its density is greater than the density of water
