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