Chapter 1: Chemistry: The Study of Change Flashcards
Chemistry
the study of matter and the changes it undergoes
scientific method
a systematic approach to research
qualitative
data consisting of general observations about the system
quantitative
data comprising numbers obtained by various measurements of the system
hypothesis
a tentative explanation for a set of observations
law
a concise verbal or mathematical statement of a relationship between phenomena that is always the same under the same conditions
theory
a unifying principle that explains a body of facts and/or those laws that are based on them
matter
anything that occupies space and has mass: water, earth, trees, air, etc
substance
a form of matter that has a definite (constant) composition and distinct properties
differ from one another in composition and can be identified by their appearance, smell, taste, and other properties
mixture
a combination of two or more substances in which the substances retain their distinct identities
do not have constant composition
can be created and then separated by physical means into pure components without changing the identities of the components
homogeneous mixture
the composition of the mixture is the same throughout: spoonful of sugar dissolves in water
heterogeneous mixture
the composition of the mixture is not uniform: sand mixed with iron fillings
element
a substance that cannot be separated into simpler substances by chemical means
114 elements identified; 82 naturally occurring, 32 created by scientists
compound
a substance composed of atoms of the two or more elements chemically united in fixed proportions
can only be separated by chemical means into pur componenets
physical property
can be measured and observed without changing the composition or identity of a substance: color, melting point, boiling point, etc
chemical property
to observe such property, must carry out a chemical change: burning, etc
cannot recover original substance via physical change
extensive property
measured value dependent on how much matter is being considered: mass, length, volume, etc
values of same extensive property can be added together
mass
the quantity of matter in a given sample of a substance
volume
length cubed
intensive property
measured value not dependent on how much matter is being considered: density, temperature, etc
values of same intensive property are not additive
density
the mass of an object divided by its volume
macroscopic properties
properties determined directly with the eye
microscopic properties
properties on the atomic or molecular scale that require detection by an indirect method
SI
International System of Units
Systeme Internationale d’Unites
weight
the force that gravity exerts on an object
liter
the volume occupied by one cubic decimeter
kelvin
the SI base unit for temperature
absolute temperature scale; lowest temperature attainable is 0K, cannot have negative value
does not have degree sign
significant figures
the meaningful digits in a measured or calculated quantity
when used, the last digit is understood to be uncertain
accuracy
how close a measurement is to the true value of the quantity that was measured
highly accurate measurements are usually precise too
precision
how closely two or more measurements of the same quantity agree with one another
measurements deviate less from averaged measurement
highly precise measurements do not necessarily guarantee accurate results
