Chemistry - Chapter 2 Vocabulary

Scientific method

is a logical approach to solving problems that lend themselves to investigation

System

a specific portion of matter in a given region of space that has been selected for study during an experiment or observation.

Hypothesis

is a testable statement that serves as the basis for predictions and further experiments.

Model

is more than a physical object; it is often an explanation of how phenomena occur and how data or events are related.

Theory

is a broad generalization that explains a body of known facts or phenomena.

Quantity

The result of nearly every measurement is a number and a unit.

SI

is used in science. It has base units: the meter (length), kilogram (mass), second (time), kelvin (temperature) mole (amount of substance), ampere (electric current), and candela (luminous intensity).

Weight

is a measure of the gravitational pull on matter.

Derived unit

include the square meter (area) and the cubic meter (volume)

Volume

is the amount of space occupied by an object.

Density

is the ratio of mass to volume.

Conversion factor

is used to convert from one unit to another.

Dimensional analysis

is a mathematical technique that allows you to use units to solve problems involving measurements.

Accuracy

refers to the closeness of a measurement to the correct or accepted value.

Precision

refers to the closeness of values for a set of measurements.

Percentage error

is the difference between the experimental and the accepted value that is divided by the accepted value and then multiplied by 100.

Significant figures

is in a number consist of all digits known with certainly plus one final digit, which is uncertain.

Scientific notation

After addition or subtraction, the answer should be rounded so that it has no more digits to the right of the decimal point than there are in the measurement that has the smallest number of digits to the right of the decimal point. After multiplication or division, the answer should be rounded so that it has no more significant figures than there are in the measurement that has the fewest number of significant figures.

Directly proportional

if two quantities are () to each other if dividing one by the others gives a constant value.

Inversely proportional

Two quantities are directly proportional to each other if dividing one by the other yields a constant value. Two quantities are inversely proportional to each other if their product has a constant value.