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111 terms

science vocab ch:1-11

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frame of reference
a system of objects that are not moving with respect to one another
relative motion
movement in relation to a frame of reference
distance
the length of the path between two points
vector
a quantity that has a direction associated with it
resultant vector
the vector sum of two or more vectors
speed
the ratio of the distance an object moves to the amount of time the object moves
average speed
the total distance traveled divided by the time it takes to travel that distance
instantaneous speed
the rate at which an object is moving at a given moment in time
velocity
the speed and direction an object is moving, measured relative to a reference point
acceleration
the rate at which velocity changes
free fall
the movement of an object toward Earth because of gravity
constant acceleration
a steady change in velocity
linear graph
a graph in which the displayed data form a straight line
nonlinear graph
a graph in which the displayed data form a curved line
periodic table
an arrangement of elements in columns, based on a set of properties that repeat from row to row
period
a row in a periodic table of elements
group
a column of elements in a periodic table
periodic table
an arrangement of elements in columns, based on a set of properties that repeat from row to row
atomic mass unit (amu)
one twelfth the mass of a carbon-12 atom
metals
elements that are good conductors of heat and electric current
transition metals
elements that form a bridge between elements of the left and right sides of the periodic table
nonmetals
elements that are poor conductors of heat and electric current
metalloids
elements with properties that fall between those of metals and nonmetals
valence electron
an electron that is in the highest occupied energy level of an atom
alkali metals
the elements in Group 1A of the periodic table, not including hydrogen
alkaline earth metals
the elements in Group 2A of the periodic table
halogens
the elements in Group 7A of the periodic table
noble gases
the elements in Group 8A of the periodic table
nucleus
the dense, positively charged mass located in the center of an atom.
proton
a positively charged subatomic particle that is found in the nucleus of an atom
electron
a negatively charged subatomic particle; the space outside the nucleus
neutron
a neutral subatomic particle that is found in the nucleus of an atom
atomic number
a unique number for each element that equals the number of protons in an atom of that element
mass number
the sum of the protons and neutrons in the nucleus in the nucleus of that atom
isotopes
atoms of the same element that have different numbers of neutrons and different mass numbers
energy levels
the possible energies that electrons in an atom can have
electron cloud
a visual model of the most likely locations for electrons in an atom
orbital
a region of space around the nucleus where an electron is most likely to be found
electron configuration
the arrangement of electrons in the orbitals of an atom
ground state
when all the electrons in an atom have the lowest possible energies
solid
the state of matter in which materials have a definite shape and a definite volume
liquid
the state of matter in which a material has a definite volume but not a definite shape
gas
the state of matter in which a material has neither a definite shape nor a definite volume
kinetic energy
the energy an object has due to its motion
pressure
the result of a force distributed over an area
absolute zero
a temperature of 0 kelvins
Charles's law
the direct proportion of the volume of a gas to its temperature (in kelvins) if the pressure and the number of particles of the gas are constant
Boyle's law
the inverse variation of the volume of a gas with its pressure if the temperature and the number of particles are constant
phase change
a reversible physical change that occurs when a substance changes from one state of matter to another
endothermic
a description of a change in which a system absorbs energy from its surroundings
heat of fusion
the energy a substance must absorb in order to change from a solid to a liquid
exothermic
a description of a change in which a system releases energy to its surroundings
vaporization
the phase change in which a substance changes from a liquid to a gas
heat of vaporization
the energy a substance must absorb in order to change from a liquid to a gas
evaporation
the process that changes a substance from a liquid to a gas at temperatures below the substance's boiling point
vapor pressure
the pressure caused by the collisions of particles in a vapor with the walls of a container
condensation
the phase change in which a substance changes from a gas or vapor to a liquid
sublimation
the phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first
deposition
the phase change in which a gas or vapor changes directly into a solid without first changing into a liquid; the placement of sediment that has been transported from another location
pure substance
matter that always has exactly the same composition; an element or compound
element
a substance that cannot be broken down into simpler substances
atom
the smallest particle of an element
compound
a substance that is made from two or more simpler substances and can be broken down into those simpler substances
heterogeneous mixture
a type of mixture in which the parts of the mixture are noticeably diferent from one another
homogeneous mixture
a type of mixture in which the substances in the mixture are so evenly distributed that it is difficult to distinguish one substance in the mixture from another
solution
when substances dissolve and form a homogeneous mixture
suspension
a heterogeneous mixture that separates into layers over time
colloid
contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension
physical property
any characteristic of a material that can be observed or measured without changing the composition of the substances in the material
viscosity
the tendency of a liquid to keep from flowing
conductivity
a material's abitlity to allow heat to flow
malleability
the ability of a solid to be hammered without shattering
melting point
the temperature at which a substance changes from solid to liquid
boiling point
the temperature at which a substance boils
filtration
a process that separates materials based on the size of their particles
distillation
a process that separates the substances in a solution based on their boiling points
physical change
occurs when some of the properties of a material change, but the substances in the material remain the same
chemical property
any ability to produce a change in the composition of matter
flammability
a material's ability to burn in the presence of oxygen
reactivity
the property that describes how readily a substance combines chemically with other substances
chemical change
occurs when a substance reacts and forms one or more new substances
precipitate
any solid that forms from a liquid mixture
science
a system of knowledge about the natural world and the methods used to find that knowledge
technology
the use of scientific knowledge to solve practical problems
chemistry
the study of the composition, structure, properties, and reactions of matter
physics
the study of matter and energy and the interactions between the two through forces of motion
geology
the study of the origin, history, and structure of the earth
astronomy
the study of the universe beyond earth
biology
the study of life and life processes
scientific method
an organized plan used for gathering, organizing, and communicating info
observation
info obtained through the senses
hypothesis
a proposed answer to a question
manipulated variable
the variable that causes a change in another variable
responding variable
a variable that changes in response to a change in the manipulated variable
controlled experiment
an experiment in which only the manipulated variable is deliberately changed at a time
scientific theory
a well-tested explanation for a set of observations or experimental results
scientific law
a statement that summarizes a pattern found in nature
model
a representation of an object or event
scientific notation
a way of expressing a value as the product between a number of 1 and 10 and a power of 10
length
a straight-line distance between points
mass
the amount of matter in an object
volume
the amount of space taken up by an object
density
the ratio of a material's mass to its volume
conversion factor
a ratio of equivalent measurements that is used to convert a quantity from one unit to another
precision
a gauge of how exact a measurement is
significant figure
all the digits in a measurement that are directly measured, plus the last digit, which is estimated
accuracy
the closeness of a measurement to the true value of what is measured
thermometer
an instrument that measures temperature
slope
the steepness of a line, equal to the ratio of a vertical change to the corresponding horizontal change
direct proportion
a relationship between two variables in which their ratio is constant
inverse proportion
a relationship in which the product of two variables is a constant when all other variables are held constant