B.Significant Figures and Precision Flashcards

A set of vocabulary flashcards covering significant figure rules, measurement uncertainty, exact numbers, accuracy, precision, and target examples from the chemistry lecture notes.

Significant figures

The digits in a measurement consisting of all certain digits plus one estimated or uncertain digit.

Certain digits

The digits in a measured value that are determined directly from the calibrated scale markings of a measuring instrument.

Estimated digit

The final, uncertain digit in a reported measurement that is approximated between the smallest scale markings of an instrument.

Measurement uncertainty

The inherent error or limitation present in any measurement, which depends upon both the skill of the measurer and the quality of the measuring tool.

Leading zeros

Zeros that appear in front of all nonzero digits in a measurement, which are never significant (for example, $0.008$ has one significant figure).

Middle zeros

Zeros that appear between other nonzero digits in a measurement, which are always significant (for example, $5.02$ has three significant figures).

Trailing zeros

Zeros that appear after all nonzero digits, which are significant if the number contains a decimal point (for example, $620.0$ has four significant figures) but ambiguous without one.

Exact numbers

Integers obtained by counting discrete objects or from defined conversions (such as $1\,\text{ft} = 12\,\text{in}$), which are considered to have an infinite number of significant figures.

Accuracy

The closeness of a measured value to the true or accepted value.

Precision

The closeness of agreement among multiple measurements of the same quantity under identical conditions (reproducibility).

psi

An abbreviation standing for pounds per square inch, which is a unit of pressure.

Archery targets measurement example

A visual representation of accuracy and precision concepts: target (a) is precise but inaccurate, target (c) is both precise and accurate, and target (d) is neither precise nor accurate.