chemistry
the study of matter and the changes that it undergoes
conclusion
a judgement based on the information obtained
control
in an experiment, the standard that is used for comparison
dependent variable
in an experiment, the variable whose value depends on the independent variable
experiment
a set of controlled observations that test the hypothesis
hypothesis
a tentative, testable statement or prediction about what has been observed
independent variable
in an experiment, the variable that the experimenter plans to change
mass
a measure of the amount of matter
matter
anything that has mass and takes up space
qualitative data
information describing color, odor, shape, or some other physical characteristic
quantitative data
numerical information describing how much, how little, how big, how tall, how fast, etc.
weight
a measure of an amount of matter and also the effect of Earth's gravitational pull on that matter
accuracy
refers to how close a measured value is to an accepted value
base unit
a defined unit in a system of measurement that is based on an object or event in the physical world and is independent of other units
conversion factor
a ratio of equivalent values used to express the same quantity in different units; is always equal to 1 and changes the units of a quantity without changing its value
density
a ratio that compares the mass of an object to its volume
derived unit
a unit defined by a combination of base units
dimensional analysis
a problem-solving method that focuses on the units that are used to describe matter
graph
a visual representation of information, such as a circle graph, line graph, or bar graph, that can reveal patterns in data
kelvin
the SI base unit of temperature
kilogram
the SI base unit for mass; about 2.2 pounds
liter
the metric unit for volume equal to one cubic decimeter
meter
the SI base unit for length
percent error
the ratio of an error to an accepted value
precision
refers to how close a series of measurements are to one another; precise measurements show little variation over a series of trials but may not be accurate
scientific notation
expresses numbers as a multiple of two factors- a number between 1 and 10, and 10 raised to a power, or exponent; makes it easier to handle extremely large or small measurements
second
the SI base unit for time
significant figure
the number of all known digits reported in measurements plus one estimated digit
percent by mass
a percentage determined by the ratio of the mass of each element to the total mass of the compound
periodic table
a chart that organizes all known elements into a grid of horizontal rows (periods) and vertical columns (groups or families) arranged by increasing atomic number
solution
a uniform mixture that may contain solids, liquids, or gases; also called a homogeneous mixture
crystallization
a separation technique that produces pure solid particles of a substance from a solution that contains the dissolved substance
chemical change
a process involving one or more substances changing into new substances; also called a chemical reaction
compound
a chemical combination of two or more different elements; can be broken down into simpler substances by chemical means and has properties different from those of its component elements
filtration
a technique that uses a porous barrier to separate a solid from a liquid
heterogeneous mixture
one that does not have a uniform composition and in which the individual substances remain distinct
homogeneous mixture
one that has uniform composition throughout and always has a single phase; also called a solution
mixture
a physical blend of two or more pure substances in any proportion in which each substance retains its individual properties; can be separated by physical means
chromatography
a technique that is used to separate the components of a mixture based on the tendency of each component to travel or be drawn across the surface of another material
states of matter
the physical forms in which all matter naturally exists on Earth- most commonly as a solid, a liquid, or a gas
solid
a form of matter that has its own definite shape and volume, is incompressible, and expands only slightly when heated
liquid
a form of matter that flows, has constant volume, and takes the shape of its container
chemical property
the ability or inability of a substance to combine with or change into one or more new substances
substance
a form of matter that has a uniform and unchanging composition; also known as a pure substance
gas
a form of matter that flows to conform to the shape of its container, fills the container's entire volume, and is easily compressed
physical property
a characteristic of matter that can be observed or measured without changing the sample's composition- for example, density, color, taste, hardness, and melting point
physical change
a type of change that alters the physical properties of a substance but does not change its composition
alpha radiation
radiation that is made up of alpha particles; is deflected toward a negatively charged plate when radiation from a radioactive source is directed between two electrically charged plates
atom
the smallest particle of an element that retains all the properties of that element; is electrically neutral, spherically shaped, and composed of electrons, protons, and neutrons
atomic number
the number of protons in an atom
beta radiation
radiation that is made up of beta particles; is deflected toward a positively charged plate when radiation from a radioactive source is directed between two electrically charged plates
electron
a negatively charged, fast- moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus
isotopes
atoms of the same element with the same number of protons but different numbers of neutrons
mass number
the number after an element's name, representing the sum of its protons and neutrons
neutron
a neutral subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton
nucleus
the extremely small, positively charged, dense center of an atom that contains positively charged protons, neutral neutrons, and is surrounded by empty space through which one or more negatively charged electrons move
proton
a subatomic particle particle in an atom's nucleus that has a positive charge of 1+
radioactivity
the process in which some substances spontaneously emit radiation
organic chemistry
area of emphasis- most carbon- containing chemicals;
examples- Pharmaceuticals, plastics
inorganic chemistry
area of emphasis- in general, matter that does not contain carbon;
examples- minerals, metals and nonmetals, semi-conductors
physical chemistry
area of emphasis- the behavior and changes of matter and the related energy changes;
examples- reaction rates, reaction mechanisms
analytical chemistry
area of emphasis- components and composition of substances;
examples- food nutrients, quality control
biochemistry
area of emphasis- matter and processes of living organisms;
examples- metabolism, fermentation