PHYSICAL SCIENCE VOCABULARY

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PHYSICAL SCIENCE VOCABULARY
acceleration- The rate of change in         atomic nucleus; has a charge of 2+, an
velocity (a change in direction or a        atomic mass of 4, and is the largest,
change in speed).                           slowest, and least penetrating form of
acid- A substance that produces             radiation.
hydrogen ions in solution; these            amalgam- An alloy containing the
solutions have a pH less than 7.            element mercury; an example is dental
alternating current (AC) - Electric         fillings.
current that reverses its direction in a    ammeter- A galvanometer that
regular pattern; the 60-Hz AC in our        measures electrical current passing
homes changes direction 120 times each      through in amperes; connected in a
second.                                     series with the circuit.
acid rain - Rain with a pH less than 5.6;   amorphous- Something that has no
produced by substances in the air           specific shape; for example, a liquid or
reacting with rainwater.                    gas.
acoustics -The study of sound.              ampere -The unit of measuring current,
actinide- Any of the 14 radioactive         the rate of flow of electrons in a circuit.
elements having atomic numbers 90-          amplification- The process of increasing
103; used in nuclear power generation       the strength of an electric signal.
and nuclear weapons.                        amplitude- In a wave, the distance from
active solar heating - Collecting the       the rest position of the medium to either
sun's energy with solar panels, heating     the crest or trough.
water with that energy, and storing the     amplitude modulated - (AM) waves -
heated water to use the energy later.       Radio waves whose amplitude is varied
aerosol -A liquid sprayed from a            with voice, music, video, or data for
pressurized container; for example, a can   transmission over long distances.
of insect spray.                            angle of incidence - In waves, the angle
air resistance - Frictional force air       formed by the incident wave and the
exerts on a moving object; acts opposite    normal.
in direction to the object's motion.        angle of reflection - In waves, the angle
alchemist -A medieval version of the        formed by the reflected wave and the
modern chemist; a practitioner who          normal (perpendicular).
blended primitive chemistry with magic,     anhydrous- A chemical compound that
seeking to turn ordinary metals into        normally has water molecules attached
gold.                                       to its ions but from which water has been
alcohol -Type of compound formed            removed.
when -OH groups replace one or more         antacid -An "anti-acid," or a chemical
hydrogen atoms in a hydrocarbon.            that changes an acid substance to a
allotropes -Different structural forms of   neutral substance.
the same element; for example, some         antifreeze -A solute added to a solvent
carbon molecules form soft graphite,        to lower the temperature at which the
whereas others form hard diamonds.          solvent will freeze.
alloy -A mixture consisting of a metal      aqueous -Describes a solution made
and one or more elements.                   with water.
alpha particle - A particle of nuclear
radiation emitted from a decaying
PHYSICAL SCIENCE VOCABULARY
Archimedes' principle - This Greek          beta particle - A negatively charged
mathematician stated that the buoyant       electron or positively charged positron
force on an object in a fluid is equal to   emitted from a decaying atomic nucleus.
the weight of the fluid displaced by the    binary compound - A chemical
object.                                     compound composed of two elements;
aromatic compounds - Chemical               for example, sodium chloride.
compounds that contain the benzene ring     biogas Mixture of gases, mostly
structure; most have distinctive odors.     methane, produced when biomass is
artificial satellite - Human-made device    allowed to rot in the absence of air.
that orbits Earth; used for                 biomass -Organic material from such
communication, weather-monitoring,          sources as wood, corn, and wastes from
military, and scientific purposes.          animals and crops.
atomic number - The number of               bionics The science of designing
protons in an atom's nucleus.               artificial replacements for parts of the
average speed - A rate of motion            human body that are not working
determined by dividing the total distance   properly.
traveled by the total travel time.          boiling point - The
average atomic mass - The average           temperature at which vapor
mass of the mixture of an element's         bubbles form in a liquid and
isotopes.                                   rise to the surface,
balance -A device used in laboratories      increasing evaporation.
to measure mass; it works by balancing a    Boyle's law - British
mass to be determined with a standard       scientist Robert Boyle
mass that is known.                         stated that volume of a gas decreases
balanced chemical equation - A              when the pressure increases, provided
chemical equation that has the same         the temperature stays the same.
number of atoms of each element on          bubble chamber - Device filled with
both sides of the equation.                 superheated liquid; used to detect and
balanced forces - Forces that are equal     monitor the path of charged nuclear
in size and opposite in direction.          particles, which leave a trail of bubbles
bar graph - A type of graph used to         as they pass though the chamber.
show information collected                  buoyant force - Ability of a fluid to
by counting; uses vertical or               exert an upward force on an object
horizontal bars of different                immersed in the fluid.
lengths to help people                      butane -A flammable gas; part of
compare quantities.                         natural gas.
base -A substance that                      byte -A basic unit of computer memory
produces hydroxide ions (OH-) in            the represents a character (number,
solution; these solutions have a pH         symbol, or alphabet letter); consists of 8
over 7.                                     bits.
Bernoulli's principle - The Swiss           calorimeter- An instrument used to
scientist Daniel Bernoulli stated that as   measure changes in thermal energy.
the velocity of a fluid increases, the      carbohydrate An organic compound
pressure exerted by the fluid decreases.    having twice as many hydrogen atoms as
                                            oxygen atoms.
PHYSICAL SCIENCE VOCABULARY
carbon 14 dating - Age-determining          which elements are in a compound and
method for carbon-containing objects up     their ratios.
to 50,000 years old.                        chemical property - A characteristic of
catalyst-A substance that speeds a          a substance that indicates whether it can
chemical reaction without itself being      undergo a specific chemical change.
permanently changed.                        chemical reaction - A change in which
cathode ray tube (CRT) - Sealed glass       one or more substances are converted to
vacuum tube that uses electrons and         different substances.
fluorescent material to produce images      chemical symbol - A shorthand way to
on a screen.                                write the name of an element; for
central processing unit - The main          example: C for carbon, Ag for silver.
circuit board inside a                      chemically stable - Describes an atom
computer that performs the                  whose outer energy level is completely
calculating and holds the                   filled with electrons.
main memory.                                chemically unstable - Describes an
centripetal acceleration -                  atom whose outer-most energy level is
Acceleration toward the                     not filled with electrons so it seeks
center of a circle by an object moving      electrons from other atoms and thus
along a circular path.                      forms compounds.
centripetal force - The force that causes   chloro Prefix that indicates presence of
an object moving along a circular path to   chlorine, as in tetrachloroethylene or
move toward the center of the path.         chlorofluorocarbon.
ceramic A material made from dried          CFC A group of compounds whose
clay or claylike mixtures.                  decomposition releases chlorine atoms
cermet A tough, heat-resistant material     that destroy ozone molecules in the
that has the properties of both a ceramic   upper atmosphere.
and an alloy; ceramic-metal.                circuit A closed path through which
chain reaction - A continuing series of     electrons flow.
fission reactions in which neutrons from    circuit breaker - A device that protects
fissioning nuclei cause other nuclei to     an electrical circuit; if too much current
split, releasing more neutrons, which       flows, the device opens the circuit,
split more nuclei, and so on.               stopping the current.
Charles's law - The volume of a gas         cloud chamber - Device filled with
increases when temperature increases,       water- or ethanol-saturated air; used to
provided the pressure stays the same.       detect charged nuclear particles, which
chemical bond - The force that holds        leave a trail as they pass through.
together the atoms in a compound; it        coagulation Process that destroys
occurs because atoms of most elements       colloid structure; can be used to reduce a
become more stable by losing, gaining,      colloidal form of air pollution.
and sharing electrons.                      coal A rock formed of ancient decayed
chemical change - The                       plants; burned as a fossil fuel.
change of substances to                     coefficient In a chemical equation, the
different substances.                       number that represents the number of
chemical formula - A                        units of each substance taking part in a
precise statement that tells                chemical reaction.
PHYSICAL SCIENCE VOCABULARY
coherent light - A beam of light in           constant speed - Speed that does not
which all the electromagnetic waves           change.
travel with the crests and troughs            contraction Movement of molecules
aligned; thus, the beam does not spread       toward one another, so that they occupy
out.                                          a smaller space.
colloid A heterogeneous mixture               combustion Rapid burning.
containing tiny particles that never settle   composite A mixture of two materials,
out; for example, milk and gelatin.           one of which is embedded in the other.
compression In compressional waves,           compound Substance made of the
the dense area of the wave.                   combined atoms of two or more
compressional wave - A type of wave           elements.
where matter vibrates in the same             compound machine - A combination of
direction the wave travels.                   two or more simple machines.
computer A device you can program to          constant In an experiment, a factor that
do calculations, make logical decisions,      does not change.
and manipulate data.                          control In an experiment, a standard for
computer virus - Type of program              comparison that is often needed to draw
designed to infect a computer, erase          a meaningful conclusion.
data, scramble other programs, or fill up     convection The transfer of energy by the
so much memory that the system is             bulk movement of matter in which
harmed.                                       particles move from place to place in
concave lenses - Lenses that are thinner      fluid, carrying the energy with them.
in the middle and thicker at the edges        convex lenses - Lenses that are thicker
and thus curve inward; form virtual,          in the middle than at the edges; can
upright, smaller images of an object.         produce both real and virtual images.
concave mirror - A mirror whose               convex mirror - A mirror with a surface
surface curves inward; produces real          that curves outward; produces upright,
images.                                       smaller, virtual images of an object.
concentrated solution - A solution in         corrosive Hazardous compound that
which the amount of solute is near the        attacks and alters metals, human tissue,
maximum the solvent can hold at that          or other materials; for example, oven
temperature.                                  cleaners and battery acid.
concentration Generally, the proportion       coulomb The charge carried by 6.24
of a solute dissolved in a solvent.           billion billion electrons.
condensation The change of a substance        covalent bond - A type of chemical
from a gas to a liquid, which usually         bond formed by atoms when they share
takes place when a gas is cooled to or        electrons.
below its boiling point.                      crest The highest point of a wave.
condense To go from the gas state to the      critical temperature - In
liquid state, due to a loss of heat.          superconductors, the very low
conduction The transfer of energy             temperature at which a material ceases to
through matter in which energy moves          have any electrical resistance.
from particle to particle.                    crystals In most solids, the arrangements
conductor A material that allows              of particles in repeating geometric
electrons to move easily through it.          patterns.
PHYSICAL SCIENCE VOCABULARY
current The flow of electrons through a      diode A type of rectifier that allows
wire or any conductor; measured in           electric current to flow in only one
amperes with an ammeter.                     direction.
deceleration The rate of change in           direct current - Electrical current that
velocity (speed and/or direction) when       flows in only one direction through a
velocity is decreasing; also called          wire.
negative acceleration.                       disinfectant A chemical that kills
decibel The unit of measure for sound        bacteria, such as alcohol.
intensity, abbreviated dB.                   dissociation – The breaking apart of an
decomposition reaction - A chemical          ionic compound into positive and
reaction in which a substance breaks         negative ions when dissolved in water.
down into two or more simpler                doping Adding an impurity to a
substances.                                  semiconductor to increase its electrical
dehydrating agent - A substance that         conductivity.
can remove water from materials.             Doppler effect - An increase or decrease
density The mass per unit volume of a        in wave frequency, caused by motion of
material; describes how tightly packed a     the source and/or motion of the observer;
substance's molecules are.                   applies to all waves.
dependent variable - In an experiment,       dot diagram - A diagram to represent
the factor whose value changes because       electrons in the outer energy level of an
of a change in the independent variable.     atom; uses the element symbols and
derived - Unit of measurement obtained       dots.
by combining SI units.                       double displacement reaction - A
detergent An organic salt similar to         chemical reaction in which two ionic
soap, except that detergents do not form     compounds in solution react, forming a
soap scum in hard water.                     precipitate, gas, or water.
diatomic molecule - A molecule               dry cell - A power source that acts as an
composed of two atoms of the same            electron pump and generates electric
element.                                     current by a chemical reaction; uses
diesel engine - An internal combustion       thick, pasty electrolyte.
engine that compresses a fuel-air            ductile – ability of metals to be pulled
mixture so much that it ignites from the     into wires
heat of compression without a spark.         effort arm - The part of a lever on
diffraction The bending of waves             which an effort force is applied.
around a barrier.                            effort force - The force applied to a
diffraction grating - A piece of glass or    machine when a machine is used to do
plastic with many parallel slits that acts   work.
like a prism, causing white light that       electric field - An area surrounding an
passes through it to separate into its       electron that exerts a force on anything
component colors.                            nearby with an electric charge; strongest
dilute solution - A solution in which the    nearest the electron and weakens with
amount of solute is much less than the       distance.
maximum the solvent can hold at that         electric motor - A device that contains a
temperature.                                 rotating electromagnet that changes
                                             electrical energy to mechanical energy.
PHYSICAL SCIENCE VOCABULARY
electrical power - The rate at which        evaporation The gradual change of a
electrical energy is converted to another   substance from a liquid to a gas at
form of energy; electrical power is         temperatures below the boiling point.
expressed in watts or kilowatts.            exothermic reaction - A chemical
electrolyte A substance that separates or   reaction in which energy is released.
forms ions in a water solution, making      Outward movement of molecules away
the solution an electrical conductor.       from one another so that they occupy a
electromagnet Strong temporary              larger space.
magnet made by inserting an iron core       expansion combustion engine - An
into a wire coil and passing an electric    engine in which the fuel is burned
current through the coil.                   outside the engine.
electromagnetic induction - Process by      experiment An organized procedure for
which electrical current is induced in a    testing a hypothesis; typically has a
wire when it is moved through a             control and dependent and independent
magnetic field.                             variables.
electromagnetic radiation - Transverse      farsighted Describes a person who sees
waves that transfer energy by radiation;    faraway things clearly, but has trouble
vary in length from very long radio         focusing on nearby objects.
waves to extremely short gamma waves.       fiberglass Hairlike strands of glass that
electron arrangement - In an atom,          make a good insulator when arranged in
how the electrons are distributed in the    puffy layers.
atom's various energy levels.               filter In working with light, a device that
electron cloud - Region where electrons     allows one or more colors to be
most probably are found surrounding the     transmitted while others are absorbed or
nucleus of an atom.                         blocked.
electrons Negatively charged particles      flammable A chemical characteristic of
that move around the nucleus of an          a substance that allows it to oxidize
atom.                                       rapidly.
electroscope A device containing two        fluid Any material that flows, such as
suspended metal leaves in a jar that        liquids and gases.
move apart when charged; used to detect     fluorescence Occurs when a material
the presence of electric charges.           absorbs ultraviolet radiation that
element Substance in which all the          stimulates it to radiate visible light.
atoms in a sample are alike.                fluorescent light - Light produced when
endothermic reaction - A chemical           ultraviolet radiation inside a fluorescent
reaction in which energy is absorbed.       light bulb causes its fluorescent coating
energy The ability to cause change.         to glow.
energy farming - The growing of plants      focal length - The distance from the
for use as fuel.                            center of a lens or mirror to its focal
energy transfer - The movement of           point.
energy from one object to another; for      focal point - A point on the optical axis
example, thermal energy flowing as heat     of a concave mirror or convex lens
from a heated stove to a skillet.           where the light rays come together.
ester An organic compound formed by         force A push or pull one body exerts on
reacting an organic acid with an alcohol.   another.
PHYSICAL SCIENCE VOCABULARY
fractional distillation - A process based     gasoline, but whose production may be
on boiling points used in oil refineries to   damaging to the environment; a biomass
separate the chemical compounds in            fuel.
crude oil into gasoline, kerosene, and        gear A wheel with teeth around its edge
other products.                               designed to mesh with teeth on another
fractionating towers - Towers at oil          gear so as to transfer force and motion.
refineries used for fractional distillation   gelatin A substance obtained by boiling
of petroleum.                                 animal bones; used in glues and goods.
free fall - How an object moves in space      generator A device that uses
when it is influenced only by gravity.        electromagnetic induction to induce
freon A refrigerant gas used in               electrical current by rotating loops of
refrigerators and air conditioners.           wire through a magnetic field.
frequency The number of wave crests           geothermal energy - Thermal energy
that pass a point during one second;          source located far below Earth's crust.
expressed in hertz.                           glass A ceramic mixture with no regular
frequency modulated - Radio waves             crystal structure.
whose frequency is varied with voice,         graduated cylinder - A cylinder marked
music, video, or data for transmission        with volume scale, used in laboratories
over long distances.                          for measuring liquid volumes.
friction The force that opposes motion        graph A visual display of information or
between two surfaces that are touching        data organized to help people interpret,
each other.                                   understand, or quickly find information.
fuel rod - A metal rod filled with            graphite A mineral made of carbon
uranium pellets, used as the fuel in a        atoms arranged in layers that easily slide
nuclear reactor.                              past one another, forming a dry
fulcrum The fixed point around which a        lubricant.
lever pivots.                                 gravity Force exerted by every object in
fuse A device that protects an electrical     the universe on every other object. The
circuit.                                      amount of force depends on the masses
galvanometer An instrument used to            of the objects and the distance between
detect electric currents.                     them.
gamma rays - High frequency                   grounded Electrically connected to
electromagnetic waves that travel at the      Earth, either directly or through a wire or
speed of light, have no mass or charge,       other metal object.
and are the most penetrating form of          group In the periodic table, each of the
radiation.                                    18 vertical columns of elements; each
gamma rays - High frequency                   group is made up of elements with
electromagnetic waves that travel at the      similar properties.
speed of light, have no mass or charge        hacker A person who uses a computer
and are the most penetrating form of          to break into other computer systems
radiation.                                    without permission.
gaseous solution - A homogeneous gas          half life - The amount of time required
that is composed of two or more gases.        for one-half of the nuclides in a sample
gasohol A mixture of ethanol and              of radioactive isotope to decay.
gasoline that is a useful substitute for
PHYSICAL SCIENCE VOCABULARY
halogens Highly active elements in            inclined plane - A simple machine
periodic table Group 17; they have seven      consisting of a sloping surface used to
electrons in their outer shells and readily   raise objects.
combine with Group 1 elements.                incoherent light - Light rays that are
heat Thermal energy that flows from a         nearly parallel, but spread out because
warmer material to a cooler material.         their electromagnetic waves do not
heat engine - A device that converts          travel in the same direction.
thermal energy that is produced by            ideal machine - A machine in which
burning fuel into mechanical energy.          work input equals work output; such a
heat mover - A device that moves              perfect machine would be frictionless
thermal energy from one location and          and 100 percent efficient
releases it in another location having a      independent variable - In an
different temperature.                        experiment, the factor adjusted to a
heat of fusion - The amount of energy         different value by the experimenter to
needed to change a material from the          see what effect it will have on the
solid state to the liquid state.              dependent variable.
heat of vaporization - The amount of          indicator An organic compound that
energy needed to change a material from       changes color in an acidic solution or a
a liquid to a gas.                            basic solution.
herbicide A chemical poison that kills        induction Electrically charging an
undesirable plants.                           object or creating an electrical current in
hertz The unit of measure for frequency.      it, without physically touching it.
heterogeneous mixture - A mixture in          inertia The tendency of an object to
which different parts can be easily           resist any change in its motion. If
distinguished.                                motionless, it tends to remain at rest; if
homogeneous mixture – A mixture in            moving, it tends to keep moving at the
which different materials are blended         same speed and in the same direction.
evenly so that the mixture is the same        infrared radiation - Electromagnetic
throughout; also called a solution.           waves that have a wavelength slightly
hydrate A compound that has water             longer than visible light; indicates the
molecules chemically attached to its ions     presence of heat.
and written into its formula.                 infrasonic waves - Waves at frequencies
hydraulic Describes a system operated         below the limit of human hearing.
by the energy of moving water.                inhibitor A substance that slows or
hydrocarbon A compound containing             prohibits a chemical reaction.
only carbon and hydrogen atoms.               instantaneous speed - The rate of
hydronium ion - The ion that makes a          motion at a given instant in time.
solution acidic.                              insulator A material that does not allow
hypothesis A testable prediction used to      heat or electrons to move through it
see how something works or to solve a         easily.
problem.                                      integrated circuit - A thin slice of
incandescent light - Light produced by        silicon, often less than 1 cm on a side,
a thin tungsten wire, or filament, that is    which can contain thousands of resistors,
heated in an incandescent bulb until it       diodes, and transistors; used in computer
glows.                                        and electronic equipment.
PHYSICAL SCIENCE VOCABULARY
intensity In sound waves, the amount of     Law of conservation of mass - A law
energy in each wave.                        stating that matter is neither created nor
interference The ability of two or more     destroyed during a chemical change.
waves to combine to form a new wave.        Law of conservation of momentum - A
internal combustion engine - An             law stating that the total momentum of a
engine in which fuel is burned inside the   group of objects is conserved unless a
engine in chambers.                         net force acts on the objects.
ion A positively or negatively charge       lever A simple machine consisting of a
atom.                                       bar that is free to pivot around a fixed
ionic bond - A type of chemical bond        point.
formed by the attraction between            line graph - A type of graph used to
opposite charges of the ions in an ionic    show trends or continuous change by
compound.                                   drawing a line that connects data points.
ionization The breaking apart of certain    lipids Fats, oils, and related organic
polar substances to form ions when          compounds.
dissolved in water.                         liquid solution - A liquid solvent that
isomers Compounds that have identical       has dissolved in it a gas, liquid, or solid.
chemical formulas but different             liter The unit of liquid volume that
molecular structures and shapes.            occupies the same volume as a cubic
isotopes Atoms of the same element that     decimeter and is slightly larger than a
have different numbers of neutrons.         quart.
joule The basic unit of energy and work.    loudness The human perception of
kelvin The SI unit of temperature.          sound intensity.
kilogram The SI unit of mass.               lubricant A substance used to reduce
kilowatt hour - The unit of electrical      friction between two surfaces that move
energy.                                     together; for example, oil,
kinetic energy - Energy in the form of      grease, or graphite.
motion, as in a moving car or truck.        machine A device that
kinetic theory of matter - The idea that    makes work easier by
all matter is made up of constantly         changing the size of the
moving, tiny particles.                     force applied to it and/or the direction of
lanthanide Any of the 14 metallic           the force.
elements having atomic numbers 58-71;       magnetic bottle - A powerful magnetic
used in magnets, ceramics, and              field that creates a container to hold the
television picture tubes.                   hydrogen plasma needed for a nuclear
laser A device that emits a beam of         fusion reaction.
photons that travel in the same direction   magnetic domains - Groups of atoms
and phase, producing a beam of coherent     with aligned magnetic poles.
light.                                      magnetic field - The region around a
Law of conservation of energy - A law       magnet where magnetic forces act.
stating that energy can change form but     magnetic poles - The two ends of a
cannot be created or destroyed under        piece of magnetic material where the
ordinary conditions.                        magnetic forces are strongest, labeled
                                            north pole and south pole.
PHYSICAL SCIENCE VOCABULARY
magnetism A property of some                microscope A optical
materials in which there is a force of      instrument that uses two
repulsion or attraction between certain     convex lenses with
like and unlike poles.                      relatively short focal
magnifier A device that                     lengths to magnify small,
makes things appear larger so               close-up objects.
that more detail can be seen;               microwaves Radio waves with the
for example, a microscope.                  highest frequency and energy; used in
malleable Ability of metals to be           communications and microwave ovens.
hammered or rolled into thin sheets.        mixture A material made of elements or
mass A measurement of the amount of         compounds stirred together but not
matter in an object.                        combined chemically.
mass number - Sum of the number of          model A symbolic representation of an
protons and neutrons in an atom's           idea, system, or structure to make
nucleus.                                    something understandable.
mechanical advantage - The number of        modulation Process of adding voice,
times a machine multiples the effort        music, video, computer information, or
force applied to it.                        other data to radio waves by using
mechanical energy - The total amount        electrical currents to vary either
of kinetic energy and potential energy in   amplitude or frequency.
a system.                                   momentum A property of any moving
medium A material through which a           object; the product of an object's mass
wave travels.                               and velocity.
melt The changing of a substance from a     monomers Organic molecules that are
solid state to a liquid state when heated   strung together to form polymers.
above the substance's freezing/melting      music Sound created using specific
point.                                      pitches, sound quality, and regular
melting point - The temperature at          patterns.
which a solid changes to a liquid.          nearsighted Describes a person who
metallic bonding - The type of chemical     sees nearby things clearly, but has
bond in which positively charged ions       trouble focusing on distant objects.
are surrounded by freely moving             net force - The sum of the forces on an
electrons.                                  object when unbalanced forces are
metalloids Elements having properties       applied to it.
of both metals and nonmetals.               neutralization A chemical reaction
metals Elements usually having these        between an acid and a base.
common properties: shiny, good              neutralize To change an acidic solution
conductors of heat and electricity, are     or a basic solution so that it is neutral.
solids at room temperature.                 neutron Atomic particle with no charge
meter The SI base unit of length.           that is part of an atom's nucleus.
microprocessor The computer's "brain."      Newton's first law of motion -
It receives input and tells the computer    Describes the relationship between
how to respond.                             velocity and forces. An object moving at
                                            a constant velocity keeps moving at that
                                            velocity unless a net force acts on it.
PHYSICAL SCIENCE VOCABULARY
Newton's second law of motion -              medicine, and so on; storing it is a
Describes the acceleration of an object in   political and environmental problem.
the direction of the net force applied to    nucleic acid - An organic polymer that
it.                                          controls the activities and reproduction
Newton's third law of motion -               of cells.
Describes action-reaction pairs; for         nucleus The positively charged center of
every action force, there is an equal and    an atom that contains protons and
opposite reaction force.                     neutrons.
NIMBY Not in my backyard; a point of         nuclide The nucleus of a specific isotope
view that supports an issue such as          having a certain specific atomic number
nuclear generation of electricity as long    and atomic mass.
as it does not take place close to home.     observation Using your senses to gather
noise Sound that has no regular pattern      information.
or definite pitch.                           ocean thermal energy conversion -
nonelectrolyte A substance, such as          Process that uses heat engines to convert
pure water, that does not conduct            differences in ocean temperatures into
electricity.                                 mechanical energy to drive turbines.
nonmetals Elements that usually are          ohm The unit for measuring resistance.
gases or brittle solids at room              Ohm's law - States that potential
temperature; most do not conduct heat or     difference equals current multiplied by
electricity well.                            resistance.
nonpolar molecule - A molecule that          opaque materials - Materials you can't
does not have oppositely charged ends.       see through because they absorb or
nonrenewable resources - Resources           reflect all light.
such as coal, oil, and natural gas, which    Optical axis - A line perpendicular to
cannot be replaced after they are used       the center of a mirror or lens.
up.                                          optical fiber - Transparent glass fiber
normal In the study of light, an             that can transmit light from one place to
imaginary line drawn perpendicular to a      another.
reflecting surface or perpendicular to a     organic compounds - Chemical
medium that light is entering.               compounds that contain the element
nuclear fission - Process in which an        carbon.
atom's nucleus is split into two nuclei      organic solvent - A type of liquid often
with smaller masses.                         found in building materials; contains
nuclear fusion - Process in which two        potentially harmful chemicals.
atomic nuclei with low masses are fused      oxidation number - A positive or
into a single nucleus of larger mass; also   negative number that indicates how
known as a thermonuclear reaction.           many electrons an atom has lost, gained,
nuclear reactor - A device that              or shared when bonding with other
generates electricity from a controlled      atoms.
nuclear fission chain reaction.              parallel circuit - An electrical circuit
nuclear waste -                              where the current flows through more
Radioactive by-products                      than one path. If one path is interrupted,
from nuclear power                           current will still flow through the other
generation, nuclear                          paths.
PHYSICAL SCIENCE VOCABULARY
pascal The SI unit of pressure.                   pitch The highness or lowness of a sound,
Pascal's principle - French scientist Blaise      which is determined by the frequency of the
Pascal stated that pressure applied to fluid is   sound waves.
transmitted unchanged through the fluid.          plane mirror - A mirror with a flat surface
passive solar heating - Direct use of the         that produces a virtual image.
sun's energy to heat something, without           plankton Tiny plants and animals that live
using fans or mechanical devices to transfer      in water and are food for small fish; they are
heat from one area to another.                    easily killed by acid rain.
period A horizontal row in the periodic           plasma A gaslike mixture of charged
table.                                            particles that exists at extremely high
periodic table - A table of the elements          temperatures.
arranged according to repeated changes in         plastic polymer-based material that can be
properties.                                       easily molded.
PET Scans that are used in medicine to            polar molecule - A molecule with opposite
reveal brain function and certain brain           charges on each end.
disorders such as tumors.                         polarized light - Light in which the
petroleum Crude oil, formed by decayed            transverse waves vibrate only along one
remains of plants and animals; a fossil fuel      plane.
that is burned and used to make lubricants        polarizing filter - A filter made of chains of
and plastics.                                     molecules in parallel rows that will transmit
pH A measure of hydronium ion                     only light waves vibrating in the same
concentration in solution.                        direction as the molecular chains.
phenolphthalein A chemical used as a color        polluted water - Water that contains high
indicator in titration; colorless in an acidic    levels of unwanted substances that may be
solution, but turns pink in a basic solution.     harmful to living things.
photon A tiny particlelike bundle of              polyatomic ion - A group of covalently
radiation.                                        bonded atoms in which the whole group is
photovoltaic cell - A device used to convert      positively or negatively charged.
solar energy directly into electrical energy;     polymer A huge molecule made up of many
also called a solar cell.                         smaller organic molecules, called
physical change - A change in the size,           monomers, that have formed new bonds and
shape, color, or state of matter.                 are linked together.
Physical property - Any characteristic of a       positron A positively charged particle
material that can be observed without             similar to an electron.
changing the identity of the material itself.     potential difference - The difference in
physical science - The study of matter and        electric potential energy between two
energy; topics for study include chemistry        different points; measured in volts.
and physics.                                      potential energy - Stored energy.
pickling A process that removes impurities        power The measure of the amount of work
from the surfaces of steel and other metals       done in a specific amount of time.
by dipping them in hydrochloric acid.             precipitate An insoluble compound formed
pigment Colored material that absorbs some        during a double-displacement reaction.
colors and reflects others; the colors of         pressure The amount of force exerted per
pigments are determined by the colors they        unit of area.
reflect.
PHYSICAL SCIENCE VOCABULARY
principle A basic rule or law describing         rectifier Any device that converts
how something always works in the natural        alternating current into direct current.
world.                                           reflecting telescope - An optical instrument
products In a chemical reaction, the             that uses a concave mirror, a plane mirror,
substances produced by the reaction.             and a convex lens to magnify distant objects.
projectile Any object shot or thrown             reflection Occurs when a wave strikes an
through the air.                                 object and bounces off.
propane A flammable gas and a part of            refracting telescope - An optical instrument
natural gas.                                     that uses two convex lenses to magnify
protein Organic polymer formed from              distant objects.
amino acids.                                     refraction The bending of waves, caused by
proton Atomic particle with a positive           changing their speed.
charge that is part of an atom's nucleus.        resistance The opposition to the flow of
pulley A simple machine consisting of a          electrons through a conductor; measured in
grooved wheel with a rope or a chain             ohms.
running along the groove.                        resistance arm - The part of a lever that
quality In sound, the difference among           exerts the resistance force.
sounds of the same pitch and loudness.           resistance force - The force exerted by a
quarks Very small particles of matter that       machine to overcome resistance to gravity or
make up protons and neutrons; presently six      friction.
different types are known.                       resonance The tendency of an object to
radiation The transfer of energy in the form     vibrate at the same frequency as another
of waves. It is a type of energy transfer that   vibrating source.
does not require matter.                         reverberation The echoing effect produced
radiator A device with a large surface area      by multiple reflections of sound.
that transfers heat to surrounding air by        RNA A nucleic acid that controls production
conduction.                                      of proteins that make new cells.
radio waves - Electromagnetic waves that         ROM In a computer, it is permanent
have long wavelengths and are used in            memory stored inside the computer, even
communications.                                  when the power is turned off.
radioactive element - An unstable element        salt A compound formed during a
whose nucleus brakes down and gives off          neutralization reaction when negative ions
particles, radiation, and energy.                from an acid combine with positive ions
radioactivity The emission of high-energy        from a base.
radiation or particles from the nucleus of a     saponification The process of making soap.
radioactive atom.                                saturated hydrocarbon - A hydrocarbon
RAM In a computer, temporary memory              that contains only single-bonded carbon
that is lost when the computer is turned off.    atoms; an example is propane.
rarefaction In compressional waves, the          saturated solution - A solution that has
less dense area of the wave.                     dissolved all the solute it can normally hold
reactants The starting substances in a           at a specific temperature.
chemical reaction.                               scientific law - A rule that describes, but
real image - An image produced where light       does not explain, a pattern in nature and
rays converge, as with a concave mirror or       predicts what will happen under specific
convex lens.                                     conditions.
PHYSICAL SCIENCE VOCABULARY
screw A simple machine consisting of a            solution A homogeneous mixture containing
special type of inclined plane wrapped in a       particles so tiny that they cannot be seen
spiral around a cylindrical post.                 even with a microscope.
second The SI unit for time.                      solvent The substance that dissolves a
semiconductor An element that conducts            solute.
electricity under certain conditions.             specific heat - The amount of energy
series circuit - An electrical circuit where      needed to raise the temperature of 1 kg of
the current has only one path. If the path is     material 1 K; it is measured in joules per
interrupted in any point, it stops current flow   kilogram per kelvin.
in the entire circuit.                            speed The rate of motion, or the rate at
SI Standard, easy to use, worldwide system        which a body changes position.
of measurement based on powers of ten. The        standard In measurement, an exact quantity
standards are used by all scientists, and are a   that everyone agrees to use as a basis of
modern version of the metric system.              comparison.
simple machine - A device that                    state of matter - Any of the four conditions
accomplishes work with only one                   in which matter can exist: solid, liquid, gas,
movement. The lever, pulley, wheel and            or plasma.
axle, inclined plane, screw, and wedge are        static electricity - The net buildup of
all examples.                                     electric charges on an object.
single displacement reaction - A chemical         step down transformer - An electrical
reaction in which one element replaces            transformer that decreases the voltage of a
another element in a compound.                    power line.
soap An organic salt made by reacting fats        step up transformer - An electrical
or oils with a strong base such as sodium         transformer that increases the voltage of a
hydroxide.                                        power line.
solar collector - A                               strong acid - An acid that ionizes almost
device that absorbs                               completely in solution; for example,
radiant energy from                               hydrochloric acid and sulfuric acid.
the sun that can be                               strong base - A base that dissociates
converted to                                      completely in solution; for example, sodium
thermal energy and                                hydroxide.
used to heat                                      sublimation The process in which a solid
buildings.                                        changes directly to a vapor without forming
solar energy - Energy from the sun. It is         a liquid.
free and can be converted into thermal            substance Matter that is an element or a
energy to heat homes and other buildings.         compound.
solubility The amount of a substance that         substituted hydrocarbon - A hydrocarbon
will dissolve in a solvent; generally             in which one or more hydrogen atoms have
expressed as the maximum number of grams          been replaced by atoms of other elements.
of solute that will dissolve in 100 g of a        supercollider A device to make protons
solvent at a specific temperature.                collide at high speed so they break apart into
solute The substance being dissolved in a         quarks.
solvent.
PHYSICAL SCIENCE VOCABULARY
superconductor A supercooled material            damage or destroy plants and animals that
that has no electrical resistance; a current     live there.
can flow indefinitely through a                  thermonuclear fusion - Nuclear fusion that
superconductor without losing energy.            occurs under conditions of
supersaturated solution - An unstable            enormous heat, as in a star.
solution that contains more solute that a        tidal energy - Energy produced
saturated solution can at that same specific     by the rise and fall of ocean
temperature.                                     levels; used to generate
suspension A heterogeneous mixture               electricity.
containing a liquid in which larger particles    time The interval between two events.
eventually settle out.                           titration Process in which a solution of
synthesis reaction - A chemical reaction in      known concentration is used to determine
which two or more substances combine to          the concentration of an acidic or basic
form a different substance.                      solution.
synthetic fiber - A thin strand of synthetic     total internal reflection - Occurs when all
polymer that can be woven into fabrics;          the light striking a surface between two
examples include nylon and Kevlar fibers.        materials is reflected totally back into the
technology The practical use of scientific       first material.
information to improve the quality of human      toxic Hazardous
life.                                            substance that can
telephoto lens - A lens having a long focal      injure living tissue.
length and producing an enlarged, close-up       tracer A radioisotope
image of an object.                              used in medical
temperature A measure of the average             diagnosis to allow
kinetic energy of the particles that make up a   doctors to monitor
sample of matter.                                human body functions, locate tumors, detect
terminal velocity - The greatest velocity        fluid movement, and so on.
reached by a falling object. It is achieved      transistor A semiconductor that amplifies
when the force of gravity is balanced by air     or strengthens an electrical signal or acts as
resistance.                                      a tiny off/on switch.
theory The most logical explanation of why       transformer A device that
things work the way they do. A former            can increase or decrease the
hypothesis that has been tested with repeated    voltage of an alternating
experiments and observations and found           current.
always to work.                                  transition element - An
thermal energy - Total energy of a               element in Groups 3-12 of
material's particles, including both kinetic     the periodic table; typically, these are metals
energy and potential energy.                     with one or two electrons in their outer
thermal expansion - A characteristic of          energy level.
almost all material that causes it to expand     translucent materials - Materials that can
when heated and contract when cooled.            be hazily seen through because they allow
thermal pollution - Pollution caused when        some light to pass through them, but not
waste heat raises the temperature of the         enough for a clear image.
environment. In bodies of water, it can
PHYSICAL SCIENCE VOCABULARY
transmutation- Changing one element to            voltmeter -A galvanometer that measures
another through radioactive decay.                potential differences in volts and is placed in
transparent materials - Materials that can        parallel across a part of the circuit.
be clearly seen through because they allow        Volume- The amount of space occupied by
light to pass through them.                       an object.
transuranium element - Any element                wave -A rhythmic disturbance that carries
having more than 92 protons, the atomic           energy through matter or space.
number of uranium.                                wavelength The distance between identical
transverse wave - A type of wave where the        points on two adjacent waves; for example,
medium moves at right angles to the               the distance between two crests or two
direction the wave is traveling.                  troughs.
trough The lowest point of a wave.                weak acid - An acid that partially ionizes in
Tyndall effect - The scattering of light by       solution; for example, carbonic acid.
particles in a mixture; this effect can be seen   weak base - A base that partially dissociates
in all colloids.                                  in solution; for example, magnesium
ultrasonic technology - Technology using          hydroxide.
high-frequency sound waves for many               Wedge- A simple machine consisting of a
different purposes such as medical                moving inclined plane with one or two
diagnoses, sonar, and jewelry cleaning.           sloping sides; examples are knives and
ultraviolet radiation - Electromagnetic           chisels.
waves that have a higher frequency than           weight -The measure of the force of gravity
visible light.                                    of an object.
unsaturated hydrocarbons - Hydrocarbons           wet cell - A power source that generates
that contain at least one double or triple        electric current by a chemical reaction using
bond between carbon atoms.                        a liquid electrolyte.
unsaturated solution - A solution that is         wheel and axle - A simple machine
capable of dissolving more solute at a            consisting of two different-sized wheels that
specific temperature.                             rotate together, such as a doorknob.
velocity -The speed and direction of a            wide angle lens - A lens with a short focal
moving body, such as a storm or a                 length that produces a relatively small image
basketball thrown across a court.                 of an object, but includes much of the
Venturi effect - Reduction in pressure of a       object's surroundings.
fluid resulting from the speed increase as        work -The transfer of energy through
fluids are forced to flow faster through          motion.
narrow spaces.                                    X rays - Electromagnetic waves having a
virtual image - An image formed of                wavelength shorter than ultraviolet
diverging light rays, as in a plane or convex     radiation; often used in medical diagnosis
mirror, or seen through a concave lens.           and photography because they can penetrate
visible radiation - Electromagnetic waves         human tissue.
in the only part of the electromagnetic
spectrum we can see--light.
volt The unit for measuring electrical
potential energy.
voltage A difference in electrical potential,
measured in volts with a voltmeter.
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