Key Terms Flashcards
accuracy
The closeness of a measurement to the actual value
base unit
A unit that defines the standard for one of the seven physical quantities in the International System of Units (SI).
calibration
The process of correcting for systematic error of a measuring device by comparing it to a known standard.
Celsius scale
A temperature scale in which the freezing and boiling points of water are defined as 0°C and 100°C, respectively.
chemical change
A change in which one or more substances are converted into one or more substances with different composition and properties.
chemical property
A characteristic of a substance that appears as it interacts with, or transforms into, other substances.
chemistry
The scientific study of matter and its properties, the changes it undergoes, and the energy associated with those changes.
combustion
The process of burning in air, often with release of heat and light.
composition
The types and amounts of simpler substances that make up a sample of matter.
controlled experiment
An experiment that measures the effect of one variable at a time by keeping other variables constant.
conversion factor
A ratio of equivalent quantities that is equal to 1 and used to express a quantity in different units.
cubic meter (m3)
The derived SI unit of volume.
data
Pieces of quantitative information obtained by observation.
density (d)
An intensive physical property of a substance at a given temperature and pressure, defined as the ratio of the mass to the volume: d = m/V.
derived unit
Any of various combinations of the seven SI base units.
dimensional analysis
A calculation method in which arithmetic steps are accompanied by canceling units that represent physical dimensions.
energy
The ability to do work, that is, to move matter.
exact number
A quantity, usually obtained by counting or based on a unit definition, that has no uncertainty associated with it and, therefore, contains as many significant figures as a calculation requires.
experiment
A set of procedural steps that tests a hypothesis.
extensive property
A property, such as mass, that depends on the quantity of substance present.
gas
One of the three states of matter. A gas fills its container regardless of the shape because its particles are far apart.
heat (q)
The energy transferred between objects because of a difference in their temperatures only.
hypothesis
A testable proposal made to explain an observation. If inconsistent with experimental results, a hypothesis is revised or discarded.
intensive property
A property, such as density, that does not depend on the quantity of substance present.
Kelvin scale
The preferred temperature scale in scientific work, which has absolute zero (0 K, or − 273.15°C) as the lowest temperature.
kelvin (K)
The SI base unit of temperature. The kelvin is the same size as the Celsius degree.
kilogram (kg)
The SI base unit of mass.
kinetic energy (Ek)
The energy an object has because of its motion.
liquid
One of the three states of matter. A liquid fills a container to the extent of its own volume and thus forms a surface.
liter (L)
A non-SI unit of volume equivalent to 1 cubic decimeter (0.001 m3)
mass
The quantity of matter an object contains. Balances are designed to measure mass.
matter
Anything that possesses mass and occupies volume.
meter (m)
The SI base unit of length. The distance light travels in a vacuum in 1/299,792,458 second.
milliliter (mL)
A volume (0.001 L) equivalent to 1 cm3.
model
A simplified conceptual picture based on experiment that explains how a natural phenomenon occurs.
natural law
A summary, often in mathematical form, of a universal observation.
observation
A fact obtained with the senses, often with the aid of instruments. Quantitative observations provide data that can be compared.
physical change
A change in which the physical form (or state) of a substance, but not its composition, is altered.
physical property
A characteristic shown by a substance itself, without interacting with or changing into other substances.
potential energy
The energy an object has as a result of its position relative to other objects or because of its composition.
precision
The closeness of a measurement to other measurements of the same phenomenon in a series of experiments.
property
A characteristic that gives a substance its unique identity.
random error
Error that occurs in all measurements (with its size depending on the measurer’s skill and the instrument’s precision) and results in values both higher and lower than the actual value.
round off
The process of removing digits based on a series of rules to obtain an answer with the proper number of significant figures (or decimal places).
scientific method
A process of creative proposals and testing aimed at objective, verifiable discoveries of the causes of natural events.
second (s)
The SI base unit of time.
SI unit
A unit composed of one or more of the base units of the Système International d’Unités, a revised form of the metric system.
significant figures
The digits obtained in a measurement. The greater the number of significant figures, the greater the certainty of the measurement.
solid
One of the three states of matter. A solid has a fixed shape that does not conform to the container shape.
state of matter
One of the three physical forms of matter: solid, liquid, or gas.
systematic error
A type of error producing values that are all either higher or lower than the actual value, often caused by faulty equipment or a consistent flaw in technique.
temperature (T)
A measure of how hot or cold a substance is relative to another substance. A measure of the average kinetic energy of the particles in a sample.
thermometer
A device for measuring temperature that contains a fluid that expands or contracts within a graduated tube.