Bob Jones Chemistry Chapter 3
Unit analysis (dimensional analysis)
Problem-solving tool that converts a measured value from 1 unit to another; must have identical units before adding, subtracting, etc.
Significant digits
The certain digit and the uncertain digit together; indicate the precision of measurements
Conversion factor
(Within unit analysis) Ratio that is constructed from the relationship of 2 measurements and their units that represent the same quantity, or equal 1
mL
1 cc= 1_____
Exponential factor
10 raised to some power
Derivative Units
22 units of measurement that are derived from the basic SI units; ex: volume = l x w x h; it is derived from SI unit for length = m3
Scientific Notation
A convenient way of expressing very large and very small numbers as a number between 1 and 9 (< 10) multiplied by an exponential factor
Unit of measurement
A label ("inches", "meters") used to specify the terms in which
SI Prefixes
G-giga M-mega K-kilo H-hecto D-deka O- measurement D-deci C-centi M-milli M-micro N-nano P-pico
Accuracy
How close a measurement is to the accepted reference or theoretical value; has a small percent error; the bulls-eye on a dart board
Precise
How finely divided the measurement scale is on an instrument; mm vs. inches
SI System
International system of Units; particular group of units within the metric system; has units for time, temperature, electrical current, and length
Pure Number
Number of units determined by actual measurements
Density
Physical property of matter Measure of concentration of matter
What are the two essential parts of measurement?
Pure number and unit of measurement
Precision
The agreement between 2 or more measurements; the reproducibility of data; how close together the darts are on the dartboard
Exponent
The power that 10 is raised to; + means how many times coefficient (number) is multiplied by 10; - means how many times it is divided by 10 (results in number between 0 and 1)
Percent error
[O-A/A\]x 100
Graduated
accurately subdivided into measurement units
Measurement
act of comparing an unknown quantity to a standard unit
Dimension
measurable quantities such as length, mass, volume, time, electrical charge
Scale
provides means of measuring when dimensional units are lined up against