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51
Science
7th Grade
03/31/2009

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Term
control group
Definition
the group that does not receive special treatment
Term
experimental group
Definition
the group that receives special treatment
Term
independent variable
Definition
the variable that is changed on purpose
Term
dependent variable
Definition
the variable that you are measuring
Term
constants
Definition
the variables that remain the same each time the experiment is conducted
Term
the law of conservation and mass
Definition
matter is neither created nor destroyed, therefore, in a chemical reaction the reactants and products must be equal in number
Term
non-point source pollution
Definition
pollution that is difficult to identify the source, such as run-off from fertilizers, litter, and erosion
Term
electron
Definition
the negatively charged particle on the outside nucleus of an atom
Term
proton
Definition
the positively charged particle found within the nucleus of an atom
Term
neutron
Definition
the particle with no charge found within the nucleus of an atom
Term
chemical change
Definition
a change that produces a whole new substance
Term
physical change
Definition
a change in appearance only
Term
endothermic reaction
Definition
a chemical reaction in which energy in the form of heat is absorbed
Term
exothermic reaction
Definition
a chemical reaction in which energy in the form of heat is released
Term
proper structure for a chemical equation
Definition
reactant + reactant --> product
Term
parts of the water cycle
Definition
evaporation, condensation, precipitation, runoff, transpiration
Term
eutrophication
Definition
the over abundance of fertilizers which cause algal bloom and then the decay of underwater grasses
Term
solution
Definition
a mixture of dissolved substances mixed evenly throughout a solvent
Term
atomic number
Definition
show the number of protons or the number of electrons in an element (number written above the symbol on the periodic table)
Term
atomic mass
Definition
shows the sum of the number of protons and neutrons in an element that tells how heavy an element is (number written below the symbol on the periodic table)
Term
compound
Definition
2 or more elements chemically combined
Term
solution
Definition
a mixture in which all material is dissolved and evenly spread throughout
Term
solvent
Definition
what does the dissolving
Term
solute
Definition
what is being dissolved
Term
pH
Definition
measures how acidic or basic a substance is on a scale of 0 - 14
Term
potential energy
Definition
energy that is stored and held in readiness
Term
kinetic
Definition
energy of motion
Term
aquifer
Definition
underground layer of soil or rock that contains water
Term
desalinization
Definition
process of removing salt from ocean water to make it usable for humans
Term
fission
Definition
the splitting of an atom's nucleus into 2 nuclei = nuclear energy
Term
weather depends on:
Definition
climate, temperature, precipitation
Term
most weather occurs in the:
Definition
troposphere
Term
winds circulate because of:
Definition
air moving in to replace the air that sank or rose
Term
temperature can be affected by:
Definition
latitude, altitude, proximity to a large body of water
Term
clouds form from:
Definition
rising air
Term
weather forecasting is:
Definition
an attempt to predict the weather
Term
fronts form by:
Definition
sinking or rising air masses
Term
warm air over land & cool air over the sea cause:
Definition
"sea breezes" which blow from the sea toward the land
Term
a cold front may form with:
Definition
the approach of a cooler air mass and an increase in air pressure
Term
problems associated with burning fossil fuels:
Definition
they do not burn clean and cause air pollution, acid rain, smog, global warming, & greenhouse effect
Term
Why is it important to manage use of fossil fuels carefully?
Definition
there is a limited amount that will run out some day & they cause pollutants
Term
What are some alternative energy sources that could be used instead of fossil fuels?
Definition
hydropower, solar energy, wind
Term
A flashlight converts chemical energy into:
Definition
electrical energy, which is then converted into radiant energy
Term
Photosynthesis uses ______________ energy to convert sunlight into food for plants
Definition
chemical
Term
Stored chemical energy that can be burned is a:
Definition
fuel
Term
No machine is 100% efficient because:
Definition
some energy is lost as heat
Term
solutes will dissolve faster when they are ___________
Definition
heated
Term
A solution will dissolve more material by ________________ it.
Definition
heating
Term
Saltwater is an example of a _____________
Definition
solution
Term
examples of physical change are:
Definition
freezing, boiling, melting, chopping, cutting
Term
examples of chemical change are:
Definition
burning, exploding, decomposing, & rusting
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