Chapter 1-7: Scientific Measurement, Density, and Specific Gravity

Vocabulary flashcards covering key concepts from scientific notation, significant figures, unit conversions, density, volume, and specific gravity.

Scientific notation

A method of writing numbers as a × 10^n where 1 ≤ a < 10; used to express very large or very small values.

Significant figures (SF)

Digits in a measurement that carry meaning about precision; used to express the uncertainty of a value.

Least number of significant figures rule (multiplication/division)

In a calculation, the result should have as many SF as the factor with the fewest SF.

Exact number

A quantity with infinite significant figures, often arising from counting or defined quantities (e.g., 1,000 m; 1 kg).

Measured number

A quantity obtained from measurement that has a finite number of significant figures.

Conversion factor

A ratio that relates two equivalent units (e.g., 1 km = 1000 m) used to convert units.

Dimensional analysis

A problem‑solving method that uses conversion factors to ensure correct units and arrive at the desired unit.

Metric prefixes (examples)

Prefixes that denote powers of ten: milli (10^-3), centi (10^-2), micro (10^-6), nano (10^-9), pico (10^-12); kilo (10^3), mega (10^6), giga (10^9).

Density

Mass per unit volume (ρ = m/V); a property that remains constant for a given substance regardless of shape.

Volume

The amount of space a substance occupies; for regular shapes, V = base area × height; for cylinder, V = πr^2h; for irregular shapes, determine by displacement.

Mass

Amount of matter in an object; measured with a balance; used with density to find volume or determine density.

Displacement method

Determining the volume of an irregular solid by measuring the rise in water level when submerged in a graduated cylinder.

Specific gravity

The ratio of a substance's density to the density of water; SG = ρsubstance / ρwater; dimensionless.

Density of water at 4°C

Defined as 1.00 g/mL; used as the reference density when calculating specific gravity.

Regular solid

A solid with a well-defined geometry (e.g., cube, cylinder) for which volume can be calculated from dimensions.

Purity test using density

Comparing a sample’s density to the known density of a pure substance to assess purity.

Mass–volume relationship (D = m/V)

With any two of mass, volume, or density known, the third can be found.

Units and conversion consistency

Ensure units are consistent and conversions yield the desired unit in calculations.

Volume of a cube

Volume of a cube is side length^3.

Volume of a cylinder

Volume of a cylinder is V = πr^2h.

Volume by subtraction (displacement method)

Calculate volume by subtracting initial from final water volume when an object is submerged.

Exact vs measured conversion factors

Some conversions are exact with infinite SF (e.g., 1,000 micrograms = 1 milligram); others are measured and carry limited SF.