Unit 1 Flashcards
Scientific Method
Approach to aquire knowledge through the observation of phenomena
Experiment
an observation of natural phenomena tested in a controlled and repeatable process; and a rational conclusion can be made
Hypothesis
A tentative and testable explanation for an observation or a series of observations
Theory
a tested explanation of basic natural phenomena
law
a statement that summarizes a vast number of experimental observations, and describes or predicts some aspect of the natural world
Rules for counting significant figures
- Nonzero integers are always significant
- Exact numbers have an infinite amount of sig figs (ex. 1 penny, 1 liter=1000mL)
- Captive zeros (zeros in between 2 sig figs) are significant
- Trailing zeros are significant (if they come after a decimal point) but not if they do not come after a decimal point
- leading zeros are not significant
precision
agreement among repeated measurements
accuracy
agreement between a measured value and the accepted or true value
Sig figs rule addition and subtraction
The number of sig figs depends on the number of decimal places in the least accurate measurement
Ex. 68+1190=1258…. answer is 1260
Sig Figs rule multiplication/division
answer based on least # of sig figs in calculation
Ex. 6.38x2.0=12.76… answer is 13(2 sig figs)
Measurement
- Essential for characterizing physical and chemical properties of matter
- contains a number and a unit
- standardization of measurement is essential
Uncertainty in Measurements
- almost all measurements contain uncertainty, different instruments can have different degrees of uncertainty
- a digit that must be estimated is called uncertain (last recording digit)
Scientific Notation
- The representation of a number in the form A.XX x 10^n
- 1<=A<=10
- n is an integer
- every digit included in A is significant
1cm^3 is???
1 mL
