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Vocabulary
Ch.1-24
66
Science
8th Grade
03/22/2007

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Term
constant
Definition
a factor that remains the same in all phases of an experiment
Term
control
Definition
standard used for comparison in an experiment
Term
hypothesis
Definition
a statement that can be tested
Term
independent variable
Definition
variable changed by the experimenter
Term
dependent variable
Definition
variable measured during an experiment
Term
inference
Definition
a conclusion drawn from an observation
Term
observation
Definition
information you gather with your senses
Term
science
Definition
the process of understanding the world
Term
scientific methods
Definition
step-by-step approach to solving problems
Term
technology
Definition
new products or tools made because of knowledge gained through science
Term
atomic number
Definition
the number of protons in an atom
Term
electron
Definition
a negatively charged particle of an atom
Term
electron cloud
Definition
region surrounding the nucleus of an atom
Term
element
Definition
a substance made up of only one type of atom
Term
isotope
Definition
atoms of the same element that have different numbers of neutrons
Term
mass number
Definition
the number of protons and neutrons in the nucleus of an atom
Term
neutron
Definition
a nuclear particle with no charge(neutral)
Term
proton
Definition
positively charged particle in the nucleus of an atom
Term
radioactive decay
Definition
the release of nuclear particles and energy
Term
transmutation
Definition
changing of one element into another through radioactive decay
Term
average atomic mass
Definition
the average mass of the mixture of its isotopes
Term
catalyst
Definition
speeds up a chemical reaction
Term
group
Definition
family of elements in the periodic table with similar physical or chemical properties
Term
metal
Definition
element that has luster, is malleable and ductile, good conductor of heat and electricity
Term
metalliod
Definition
an element that shares some properties with metals and some with nonmetals
Term
nonmetal
Definition
are usually gases or brittle solids at room temperature and are poor conductors of heat and electricity
Term
period
Definition
horizontal row of elements whose properties change gradually and predictably
Term
representative elements
Definition
groups 13-18, include metals, metalloids, and nonmetals
Term
semiconductor
Definition
does not conduct electricity as well as a metal but conducts it better than a nonmetal
Term
synthetic elements
Definition
elements that do not occur naturally and are made in laboratories
Term
transition elements
Definition
groups 3-12, are all metals
Term
activation energy
Definition
minimum amount of energy needed to start a chemical reaction
Term
chemical reaction
Definition
process that produces chemical change, resulting in a new substance
Term
concentration
Definition
amount of substance present in a certain volume
Term
chemical equation
Definition
shorthand form to show which reactants are used and which products are formed in a chemical reaction
Term
endothermic reaction
Definition
chemical reaction in which heat energy is absorbed
Term
enzyme
Definition
protein that helps chemical reactions in organisms occure more quickly
Term
exothermic reaction
Definition
chemical reaction in which heat energy is released
Term
inhibitor
Definition
substance that slows down a chemical reaction
Term
product
Definition
substance that forms as a result of a chemical reaction
Term
rate of reaction
Definition
measure of how fast a chemical reaction occurs
Term
reactant
Definition
substance that exists before a chemical reaction begins
Term
Archimedes' principle
Definition
states that the buoyant force on an object is equal to the weight of the fluid displaced by the object
Term
buoyant force
Definition
upward force exerted on an object immersed in a fluid
Term
condensation
Definition
change of matter from a gas to a liquid state, such as water vapor changing to a liquid
Term
density
Definition
mass of an object divided by its volume
Term
freezing
Definition
change of matter from a liquid state to a solid state
Term
gas
Definition
matter that does not have definite shape or volume
Term
heat
Definition
movement of thermal energy from a substance at a higher temperature to a substance at a lower temperature
Term
liquid
Definition
matter with a definite volume but no definite shape
Term
matter
Definition
anything that takes up space and has mass
Term
melting
Definition
change of matter from a solid state to a liquid state
Term
Pascal's principle
Definition
states that when a force is applied to a confined fluid, an increase in pressure is transmitted equally to all parts of the fluid
Term
pressure
Definition
force exerted on a surface divided by the total area over which the force is exerted
Term
solid
Definition
matter with a definite shape and volume, has tightly packed particles
Term
force
Definition
a push or a pull
Term
vaporization
Definition
change of matter from a liquid state to a gas
Term
acceleration
Definition
change in belocity divided by the amount of time needed for that change to take place
Term
balanced forces
Definition
describes forces that are equal but opposite in direction
Term
displacement
Definition
measures the distance and direction from a starting point to an ending point
Term
first law of motion
Definition
states that an object will remain at rest or move in a straight line at a constant speed unless it is acted upon by a force
Term
friction
Definition
1
Term
second law of motion
Definition
1
Term
speed
Definition
1
Term
third law of motion
Definition
1
Term
unbalanced forces
Definition
1
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