Mastering Chemistry Chapters 2 & 3.1-2

Intensive Property

A property that does not change as the amount of substance changes and can be used to identify a substance.

Extensive Property

A property that changes as the amount of substance changes and cannot be used to identify a substance.

Measured Numbers

Numbers obtained when a quantity is determined by using a measuring device.

Significant Figures

The numbers recorded in a measurement that show its precision.

Exact Numbers

Numbers obtained by counting items or through definitions comparing two units in the same measuring system.

Rounding Rules for Significant Figures

If the first digit to be dropped is 4 or less, drop it; if it is 5 or greater, increase the last retained digit by 1.

Multiplication and Division Rule

The final answer should have the same number of significant figures as the measurement with the fewest significant figures.

Addition and Subtraction Rule

The final answer should have the same number of decimal places as the measurement with the fewest decimal places.

Density

The relationship of the mass of an object to its volume expressed as grams per cubic centimeter (g/cm³).

Pure Substance

Matter that consists of only one type of atom or molecule.

Element

The simplest type of pure substance that cannot be broken down into simpler substances.

Compound

A pure substance that consists of two or more elements.

Homogeneous Mixture

A mixture with a uniform composition throughout.

Heterogeneous Mixture

A mixture with a non-uniform composition where components can be seen.

Physical Property

A property that can be measured without changing the substance into another substance.

Physical Change

A change where some part of the matter changes but the matter retains its composition.

Chemical Property

A property that can only be measured when a substance changes into a new substance.

Chemical Change

A change where one or more original substances are converted into one or more new substances.