Physical Science Glossary
absolute
magnitude
The brightness of a star if viewed from a distance of 32.6 light
years; the scale ranges from -8 to 16, with -8 being the brightest
and 16 the faintest (Lesson 31)
absolute zero
The lowest point on the Kelvin scale (Lessons 19, 31)
acceleration
The rate of change in velocity; includes speeding up, slowing
down, and changing direction (Lessons 15, 16)
accuracy
The closeness of a measurement to the actual value of what is
being measured (Lesson 3)
accretion
The process by which planets and other bodies in the solar system
are created (Lesson 30)
acid
A substance that donates protons (hydrogen ions); any compound
that produces hydrogen ions in a solution (H+); a substance with a
pH of less than 7 on the pH scale (Lesson 14, Lab 2)
acid rain
Rain or any other type of precipitation that is abnormally acidic as
a result of air pollution (Lesson 14)
actinide series
Radioactive group of elements consisting of elements 89 through
103 on the periodic table (Lesson 9)
activated
Highest point or peak on an energy diagram; represents the
complex
highest energy point between the reactant's and product's
transition state (Lesson 12)
activation energy Amount of energy needed to start a reaction (Lessons 12, 13)
air resistance
Friction acting on an object moving through the air (Lesson 16)
alkali
A base; any substance having basic properties as opposed to acidic
(Lesson 14)
alkali metal
Metal element belonging to group 1 of the periodic table (Lesson
9)
alkaline earth
Metal element belonging to group 2 of the periodic table, not
metal
including hydrogen (Lesson 9)
alpha particle
A positively charged particle emitted during the radioactive decay
of some unstable atoms (Lesson 25)
alternating
A flow of electric charge that regularly reverses direction (Lesson
current
23)
amplitude
The maximum distance that the medium of a wave is displaced
from its resting position (Lessons 20, 21)
anion
A negatively charged ion (Lessons 8, 10, 11)
Antarctic Circle
The circle of latitude south of which, on the solstices, every
location experiences a period of continuous day or night (Lesson
29)
aphelion
The point in a planet's orbit at which it is farthest from the Sun
(Lesson 29)
aqueous
Dissolved in water or relating to water (Lessons 12, 13)
Arctic Circle
The circle of latitude north of which, on the solstices, every
location experiences a period of continuous day or night (Lesson
29)
asteroid
An irregularly shaped, rocky object that orbits the Sun and is
believed to be formed from the same material as planets (Lesson
asthenosphere
atmosphere
atmospheric
pressure
atom
atomic mass
atomic mass unit
atomic number
Atomic Theory
atomic structure
attraction
average speed
average velocity
axis
background
radiation
balanced force
bar graph
base
base units
beta particle
The Big Bang
Theory
binary compound
biochemical
black hole
30)
Partly molten layer of the Earth that lies below the lithosphere
(Lesson 26)
The body of gases that surrounds a celestial body such as Earth
(Lesson 28)
The weight of the air mass that surrounds Earth and exerts
pressure on all points of the planet (Lesson 28)
Building block of matter, the smallest particle of an element
(Lessons 5, 8, 10, 23, 24, 25)
The sum of protons and neutrons in the nucleus of an atom; mass
number (Lessons 8, 9)
Special unit of mass used to express the mass of atoms and
molecules (Lesson 8)
The number of protons in the nucleus of an atom (Lesson 9)
Proposed explanation of the structure, properties, and behavior of
the atom (Lesson 8)
The structure of an atom, consisting of a nucleus with a positive
charge that is surrounded by negatively-charged electrons (Lesson
24)
An electric or magnetic force that acts between oppositely charged
bodies; bring together (Lesson 24)
The average of all speeds traveled during a given time; the total
distance divided by the time it takes to travel that distance (Lesson
15)
Velocity of an entire trip, found by dividing the change in distance
by the time it took to travel the distance (Lesson 15)
The invisible line on which the Earth rotates that runs through the
Earth from the North Pole to the South Pole (Lesson 29)
Radiation that occurs naturally in the environment or is received as
cosmic rays (Lesson 25)
When all the forces in a system cancel each other out and the net
force is 0 N (Lesson 15)
A graph using comparative bars of different lengths to represent
data (Lesson 4)
A substance that accepts protons (hydrogen ions); any compound
that produces hydroxide ions (OH-); a substance with a pH of more
than 7 on the pH scale (Lesson 14, Lab 2)
Seven units of measurement that are considered to be
"dimensionally independent," according to the BIPM (Lessons 3,
15)
An electron given off by an unstable nucleus (Lesson 25)
The theory on the origins of the present day universe that states
that the universe started as a small mass that gradually expanded
to its current size and shape (Lesson 31)
A compound made up of only two elements (Lesson 11)
A type of sedimentary rock that is formed from the remains of
organisms (Lesson 27)
An extremely dense region of space where the gravitational pull is
boil
boiling point
bond
Boyle's Law
brittle
buffer
buoyancy
catalyst
cation
caustic
cementation
centrifugal force
centripetal
acceleration
centripetal force
chain reaction
Charles's Law
chemical bond
chemical change
chemical
equilibrium
chemical
equation
chemical formula
chemical
property
chemical reaction
chemistry
so massive that nothing can escape its force (Lesson 31)
To reach the boiling point and change from a liquid to vapor
(Lesson 7)
Temperature at which a liquid boils; the temperature at which a
substance changes from a liquid to a gas (Lesson 7)
Attractive force that holds atoms and ions together (Lesson 10)
The pressure and volume of a gas at a constant temperature are
inversely proportional to each other. (Lesson 6)
Easily shattered or broken (Lessons 9, 26)
A solution that is able to resist large changes in pH (Lesson 14)
Upward force exerted on an object in liquid that causes it to float
because the liquid has a greater density than the object (Lesson
13)
A substance used to speed up a chemical reaction but that is not
consumed in the reaction (Lesson 12)
A positively charged ion (Lessons 8, 10, 11)
Capable of destroying, damaging, or eating away at another
substance; any chemical substance that burns or destroys living
tissue (Lesson 14)
The last stage in the formation of sedimentary rock; formed when
mineral material bonds with sediment clasts (Lesson 27)
The outward push on an object when it is moving in a circle
(Lesson 16)
The acceleration of an object traveling around a circle or portion of
a circle as it constantly changes direction (Lesson 16)
A force that continuously changes the direction of an object to
make it move on a circular path (Lesson 16)
A rapid series of nuclear reactions triggered by the release of
neutrons during fission; can be controlled or uncontrolled (Lesson
25)
At a constant pressure and with a fixed amount of gas, volume and
temperature are directly proportional to each other. (Lesson 6)
Attractive force that holds atoms or ions together (Lesson 10)
Alteration of a chemical property of a substance that results in the
formation of a new substance (Lessons 5, 13)
Type of reversible reaction occurring when the rate of the forward
reaction is equal to the rate of the reverse reaction (Lesson 12)
A representation of a chemical reaction using chemical symbols
and formulas (Lesson 12)
A way of writing a compound's name using symbols; a formula
used to describe the number and type of atoms or ions in an
element or compound (Lesson 11)
A characteristic of a substance that describes a type of chemical
change it can undergo (Lesson 5)
A process by which one substance is transformed into another; a
process in which a chemical change occurs (Lessons 9, 12)
Study of the properties, composition, structure, and reactions of
matter (Lesson 5)
circle graph
circuit
circumference
classical planets
clast
cleavage
closed system
cochlea
coefficient
collide
collision theory
colloid
color
coma
Combined Gas
Law
combustion
reaction
comet
compaction
compound
compound
machine
compression
concave lens
concave mirror
A graphic representation of the parts that make up a whole
amount; also called a pie chart (Lesson 4)
A complete path around which electric current can flow (Lesson
23)
The perimeter, or distance around, a circle; the distance around
the widest point of a sphere (Lesson 29)
The eight planets of the solar system (Lesson 30)
A particle that is formed by the weathering of existing rock
material (Lesson 27)
The tendency of certain minerals, rocks, etc to break in certain
directions (Lesson 27)
A system that is isolated from any forces except those acting
inside it (Lessons 15, 16, 17)
The fluid-filled canal in the ear that contains nerve cells that
vibrate to send electrical impulses to the brain (Lesson 21)
A number that is placed in front of a symbol or a compound
formula in a chemical equation that indicates how many atoms or
molecules of that substance are involved in each reactant and
product (Lesson 12)
Come together, bump into each other (Lesson 12)
Theory that states for a reaction to occur, the particles in the
reactants must come together and collide with enough energy to
break the bonds and form new bonds (Lesson 12)
Heterogeneous mixture of tiny particles dispersed evenly
throughout a solid, liquid, or gas (Lesson 13)
A physical property test that identifies the coloring of a mineral
(Lesson 27)
The sphere of vaporized gas and dust that surrounds the nucleus
of a comet as it approaches the Sun (Lesson 30)
The pressure and volume of a gas are inversely proportional to
each other, but directly proportional to the temperature of that
gas. (Lesson 6)
A chemical reaction that occurs when oxygen combines with other
substances, often producing heat and light (Lesson 12)
A celestial body that orbits the Sun and is formed from dust, ice,
rock fragments, and frozen methane and ammonia (Lesson 30)
The process by which sedimentary rock is formed by the
compression of clasts (Lesson 27)
A substance made from two or more elements chemically bonded
together and that can be chemically broken down into those
substances (Lessons 5, 8, 9, 10, 11)
Machine made of two or more simple machines (Lesson 18)
An area in a longitudinal wave in which the particles in the medium
are spaced close together (Lessons 20, 21)
A lens that curves inward in the middle and is thicker at the top
and bottom (Lesson 22)
A mirror in which the inside of a curved surface is reflective
(Lesson 22)
concentrate
To make a mixture stronger by adding more of the solute (Lesson
13)
concentration
A measure of the strength of a solution; the number of molecules
of a substance in a determined volume (Lessons 12, 13)
condensation
Phase change that occurs when a vapor or gas turns into a liquid
(Lessons 7, 28, Lab 4)
conduction
The transfer of thermal energy without a transfer of matter
(Lesson 19)
conductor
A material through which heat, electricity, or sound can flow easily
(Lessons 23, 24, Lab 3)
conjugate acid
The compound formed when a proton is added to a base; differs
from a base pair by the presence of one proton, or H+ (Lesson 14)
conjugate base
The compound formed when an acid loses a proton (Lesson 14)
control
A standard of comparison in a scientific experiment (Lesson 1)
constant speed
An object traveling at a steady speed (Lesson 15)
constructive
Two or more waves that combine to produce a wave with a larger
interference
amplitude (Lessons 20, 21, 22)
Continental Drift Theory that proposes that about 225 million years ago, the seven
Theory
continents of the Earth originally came from one single continent
(Lesson 26)
convection
Heat transfer that occurs by the circulation of a moving liquid or
gas (Lesson 19)
convection
The circular pattern of fluid formed by the heating and cooling of
current
magma in the asthenosphere (Lesson 26)
convergent plate Two plates on the Earth's crust that collide and push into each
boundary
other (Lesson 26)
convex lens
A lens that curves outward and is thicker in the middle (Lesson 22)
convex mirror
A mirror in which the outside of a curved surface is reflective
(Lesson 22)
core
Hot mixture of metal, mostly iron and nickel, that makes up the
center of the Earth (Lessons 26, 29)
corrosive
Capable of damaging and destroying materials on contact (Lesson
14)
cosmology
The study of the structure and evolution of the universe (Lesson
31)
covalent bond
A chemical bond that occurs between atoms sharing a pair of
valence electrons (Lesson 10)
covalent
Type of compound formed when non-metals bond by sharing
compound
electrons (Lessons 11, 13)
crest
The highest point of a wave above the rest position (Lesson 20)
critical angle
The angle of incidence that causes light to refract at a 90 degree
angle (Lesson 22)
critical point
The temperature at which the liquid phase of a substance no
longer exists and at which a substance will be a gas regardless of
the pressure (Lesson 7)
crust
The outer layer of the Earth (Lesson 26)
crystal
A solid made up of molecules arranged in a fixed structure; i.e.
salt (Lesson 11)
crystalline
Atoms and molecules that are arranged in a fixed shape, such as
structure
those in a mineral (Lesson 27)
crystallize
A form of solid made up of molecules that are neatly arranged in
regular and specific repeating patterns (Lesson 13)
customary units The system of weights and measures used in the United States;
also known as English units (Lesson 3)
data
A body of facts, statistics, or information (Lesson 1)
data table
Facts, statistics, or information displayed in column format (Lesson
4)
decomposition
A chemical reaction that occurs when a compound breaks down
reaction
into simpler substances (Lesson 12)
density
The measure of how heavy something is for its size; the state or
quality of being dense; mass per unit volume (Lessons 5, 21)
dependent
A part of an experiment or set of data that is affected by an event
variable
or another variable (Lesson 1)
deposition
Phase change that occurs when a gas transforms into a solid,
skipping the liquid phase (Lesson 7)
derived units
Units of SI measurement that are made when the base units are
combined algebraically (Lesson 3)
destructive
Two or more waves that combine to produce a wave with a smaller
interference
amplitude (Lessons 20, 21, 22)
detrital
A type of sedimentary rock formed from the compaction and
cementation of clasts (Lesson 27)
diameter
The distance from one point of a circle's or sphere's circumference
to another when passing through the center point (Lesson 29)
diatomic element Pure elements that, in nature, form molecules containing two
atoms of the same element; i.e. hydrogen exists as H 2 (Lesson 10)
diatomic
Molecules made of only two atoms of either the same or different
molecule
elements; i.e. NaCl or O2 (Lesson 10)
diffraction
The bending of a wave as it moves around an obstacle or passes
through an opening (Lessons 20, 21)
diffuse reflection Type of reflection that occurs when parallel light waves strike an
uneven surface and bounce off in many different directions (Lesson
22)
dilute
To make the strength of a mixture weaker or less concentrated by
adding more solvent (Lesson 13)
direct current
A type of continuous charge that moves in one direction; also
known as DC (Lesson 23)
displacement
Moving or putting out of the usual or proper place (Lessons 20, 21)
dispersion
Method of dissolving that occurs when a substance breaks apart
into tiny particles and spreads throughout the solvent (Lesson 13)
dissociation
Method of dissolving that occurs when an ionic compound
separates into ions as it dissolves (Lesson 13, Lab 2)
dissolve
The process by which solid particles mix with a liquid and appear
to become part of the liquid; i.e. dissolving salt in water; to pass
into or become part of a solution (Lessons 11, 13)
divergent plate
Plate movement in which two plates move away from each other
boundary
Doppler effect
(Lesson 26)
sound: The change in a sound's frequency caused by the motion of
the sound's source, the listener's position, or both (Lesson 21)
light: The measurable shift in color used to determine a celestial
object's movement with respect to the observer (Lesson 22)
dosimeter
Device that measures the amount of radiation to which one is
exposed over time (Lesson 25)
double bond
Type of bond formed when atoms share two pairs of electrons
(Lesson 10)
double
A chemical reaction that occurs when elements from two
replacement
compounds replace each other to form two new compounds by
reaction
exchanging positive ions (Lesson 12)
downdraft
Fast-moving cool air (Lesson 28)
ductile
Easily made into a wire (Lessons 9, 10)
dwarf planet
A celestial body that is similar to a planet, but its gravitational pull
is too weak to clear all debris from its orbit path (Lesson 30)
dynamic
A reversible reaction that is balanced so the concentration of the
equilibrium
reactants is equal to the concentration of the products and does
not change over time (Lesson 12)
eardrum
The membrane that separates the outer and middle ear that
vibrates at the same frequency as the sound waves that strike it
(Lesson 21)
Earth’s gravity
Force that the Earth exerts on all objects at or near its surface
(Lesson 5)
earthquake
A series of vibrations in the Earth's crust caused by built up strain
(Lesson 26)
eclipse
When two celestial bodies align with the Sun, one blocking the
light of the Sun from the other (Lesson 29)
effective collision Reactants that come together and collide with enough energy to
break their bonds and form new ones (Lesson 12)
efficiency
The ratio of work put out by a machine to the work put into that
machine; a measure of how well something gets a job done with
little waste of time and energy (Lesson 18)
electric charge
A property that causes the particles that make up atoms (such as
protons and neutrons) to attract or repel each other (Lesson 23)
electric circuit
A closed path along which electrons can flow (Lesson 23, Lab 3)
electric current
The continuous flow or movement of an electric charge (Lessons
23, 24, Lab 3)
electric field
A region of space that is characterized by the presence of an
electric force (Lesson 22)
electric force
The attraction or repulsion between electrically charged objects
(Lesson 23)
electrolyte
Compound within the body that dissolves in water and separates
into ions (Lessons 11, 13, Lab 3)
electromagnet
A very strong temporary magnet that can be turned on and off
(Lesson 24)
electromagnetic The motion of a conductor through a magnetic field to produce
induction
electric current (Lesson 24)
electromagnetic
radiation
electromagnetic
spectrum
electromagnetic
wave
Electromagnetic waves that transfer energy by traveling through
matter or empty space (Lesson 22)
The entire range of frequencies of electromagnetic radiation
(Lessons 22, 25)
A wave that is made up of changing electric fields and changing
magnetic fields; considered a transverse wave (Lessons 20, 21,
22, 24, 25)
electromagnetism The relationship between electric and magnetic fields and their
interactions with each other (Lesson 24)
electron
A negatively charged particle located outside the nucleus of an
atom (Lessons 8, 10, 19, 23, 24)
electron dot
A diagram that uses dots to show an element's valence electrons;
diagram
also called a Lewis diagram or Lewis dot diagram (Lesson 10)
electrostatic field Space surrounding a static electric charge (Lesson 8)
element
Any of 118 known substances that make up matter and cannot be
separated into simpler substances; also called chemical element
(Lessons 5, 8, 9)
empirical formula The simplest formula for a compound; shows the simplest ratio in
which atoms can combine and form a compound (Lesson 11)
endothermic
A reaction that absorbs or takes in energy from its surroundings
(Lesson 12)
energy
The ability to move or change matter; the ability to do work
(Lessons 12, 17, 18)
energy diagram A graph plotting the energy change of a system as a chemical
reaction proceeds (Lesson 12)
energy level
The possible energy that electrons in an atom must have; the path
of a given electron's orbit around a nucleus (Lesson 8)
enzyme
A protein that acts as a catalyst for specific reactions (Lesson 14)
equilibrium
State of balance; occurs in a system when opposing forces balance
and cancel each other out to equal zero (Lesson 12)
equinox
The time when the Earth is tilted neither towards nor away from
the Sun, resulting in a night and day of equal length (Lesson 29)
evaporation
Process that changes a liquid to a gas at temperatures below the
boiling point (Lesson 7)
exosphere
The highest region of the Earth's atmosphere (Lesson 28)
exothermic
A reaction that releases or gives off energy (Lesson 12)
extrusive
A type of igneous rock formed on Earth's surface (Lesson 27)
eye
The calm, low-pressure center of a hurricane (Lesson 28)
family
A column or group of elements on the periodic table (Lesson 9)
fission
A nuclear reaction that involves the splitting of an atomic nucleus
into smaller parts (Lesson 25)
flame test
Procedure in chemistry used to detect the presence of certain
metal ions; a sample is placed under a flame and the color of the
flame identifies the metal in the sample (Lesson 9)
flux lines
Magnetic lines of force that circle a magnet (Lesson 24)
focal point
The point at which the light rays parallel to a mirror or lens meet
or appear to meet (Lesson 22)
foliated
Rock texture characterized by the presence of layered mineral
grains (Lesson 27)
force
An action that causes an object to accelerate; equal to the product
of an object's mass and acceleration (Lessons 15, 16, 17, 18)
fossil fuel
Naturally occurring organic compounds that undergo combustion
reactions to provide energy (Lesson 12)
frequency
The number of cycles of periodic motion that pass by a point in a
given amount of time (Lessons 20, 21)
friction
A force that opposes motion between two objects that touch
(Lessons 15, 16, 18, 19, 20, 23)
fulcrum
In a lever, the point around which a bar pivots (Lesson 18)
fusion
A nuclear reaction in which the nuclei of two atoms combine to
make a larger nucleus (Lessons 25, 31)
galaxy
A system of stars, gas, and dust that is located within the universe
(Lesson 31)
gamma ray
A ray of energy emitted by an unstable nucleus (Lesson 25)
gas
State of matter that has no definite shape or volume (Lesson 6)
gas law
Any of a group of laws that illustrate the relationship between
temperature, pressure, and volume in gases (Lesson 6)
Gay-Lussac's Law At a constant volume and with a fixed amount of gas, pressure and
temperature are directly proportional to each other (Lesson 6)
geocentric model The model of the solar system that places the Earth at the center,
with satellites orbiting around it (Lesson 30)
geographic poles Either of two fixed points on the surface of a planet; in this case,
Earth (Lesson 24)
grain size
The size of a rock's mineral crystals (Lesson 27)
gravitational
The potential energy that exists between the Earth and every
potential energy object on it due to the force of gravity (Lessons 17, 18)
gravitational pull The force produced by a mass that causes other objects to be
attracted to it (Lesson 30)
gravity
Attraction between two objects due to their masses that increases
with mass and decreases with distance (Lessons 16, 17, 26, 30)
greenhouse
The process by which gasses trap heat in the atmosphere,
effect
warming surface temperatures of a planet (Lesson 28, 30)
group
A column of 18 elements on the periodic table; also called a family
(Lesson 9)
hail
A type of precipitation that is formed from ice crystals that
condense within a thunderstorm cloud (Lesson 28)
half-life
The time required for one half of a sample of a radioisotope to
decay (Lesson 25)
halogen
Non-metallic gaseous element belonging to group 17 of the
periodic table of elements (Lesson 9)
hardness
A physical property test that identifies the strength of a mineral
(Lesson 27)
heat
The transfer of thermal energy from one object to another due to a
difference in temperature (Lesson 19)
heating curve
Plot of temperature versus time showing the various states of a
substance (Lesson 7)
heliocentric
The model of the solar system that places the Sun at the center,
model
heliosphere
heterogeneous
mixture
high pressure
system
homogeneous
mixture
Hubble's
Constant
Hubble's Law
with satellites orbiting around it (Lesson 30)
The region of the universe that is influenced by the solar wind
(Lesson 30)
A mixture composed of substances that are unevenly mixed
(Lesson 13)
Weather condition that occurs in areas of high atmospheric
pressure and usually results in stable conditions (Lesson 28)
A mixture composed of substances that are evenly mixed and have
a uniform composition, uniform appearance, and definite
properties (Lesson 13)
The rate at which the universe is currently expanding (Lesson 31)
The redshift in light coming from distant galaxies is proportional to
their distance. (Lesson 31)
hurricane
Powerful cyclonic storm that develops over warm subtropical
waters (Lesson 28)
hydrocarbon
Compound composed of hydrogen and carbon (Lesson 12)
hydronium ion
Compound that results from adding a hydrogen ion to a water
molecule (Lesson 14)
hypothesis
pl. hypotheses; A proposition set forth as an explanation of a
certain phenomenon (Lessons 1, 22, 29)
ideal machine
A theoretical machine in which the input work is equal to the
output work and no energy is lost (Lesson 18)
ideal mechanical An object's mechanical advantage if there were no friction involved
advantage
in the system (Lesson 18)
igneous rock
A rock that is formed from hardened magma (Lesson 27)
inclined plane
A flat surface that is slanted; one of the six simple machines
(Lesson 18)
independent
A variable that is not affected by other variables or events in an
variable
experiment (Lesson 1)
index of
The ratio of the speed of light in a vacuum to the speed of light in
refraction
a medium (Lesson 22)
indicator
A substance that changes color to signal the presence of an acid or
base (Lesson 14, Lab 2)
induction
Method of charging an object with static electricity or without
contact between the materials (Lesson 23)
inertia
The tendency of matter to resist change to its motion, whether it is
moving or at rest (Lessons 15, 16, 30)
infiltration
Absorption of water into the ground or soil (Lesson 7)
The Inflation
The addition to the Big Bang Theory that explains that the universe
Theory
expanded rapidly over a short period of time and that it is still
expanding (Lesson 31)
infrasound
Sound with frequencies too low to be heard by the human ear but
that may be felt as vibrations (Lesson 21)
inorganic
Compound that is not formed from plant or animal remains
(Lesson 27)
input force
The force that is applied to a machine; represented by Fin (Lesson
18)
input work
inner core
insoluble
instantaneous
velocity
insulator
intensity
International
System of Units
(SI)
intrusive
The work that is done on a machine; represented by Win (Lesson
18)
The innermost part of a core such as the dense, solid center of the
Earth's core (Lesson 26)
Unable to dissolve; does not dissolve (Lesson 13, Lab 1)
The speed and direction of an object at any particular moment
(Lesson 15)
A material through which energy cannot flow easily (Lessons 19,
23, Lab 3)
Energy and force per unit of area, volume, time, etc; the rate at
which a wave's energy flows through a given area (Lessons 21, 22)
The system of universal units of measurement based on the
meter-kilogram-second system (Lessons 3, 5, 6, 31)
A type of igneous rock that is forced between pre-existing rocks or
layers (Lesson 27)
ion
An atom that is electrically charged as a result of having more or
less electrons than protons (Lessons 8, 10, 11, 13, 14, 23)
ionic bond
Attractive force that holds ions together (Lesson 10)
ionic compound Chemical compound of cations and anions held together by ionic
bonds (Lessons 10, 11, 13)
ionization
Process by which a neutral atom or molecule loses or gains
electrons (Lesson 13)
isotope
Atoms of an element that have the same number of protons but
different numbers of neutrons, and therefore a different atomic
mass (Lessons 8, 9, 25)
Jovian planets
The gas rich, outer planets of the solar system: Jupiter, Saturn,
Uranus, and Neptune (Lesson 30)
kinetics
The study of the actions of forces and reaction rates in chemical
reactions (Lesson 12)
kinetic energy
The energy that an object possesses because of its motion
(Lessons 6, 7, 17, 18, 19)
kinetic friction
The friction between two moving surfaces (Lesson 15)
kinetic theory of Matter is made up of small particles, atoms, or molecules that are
matter
always in random motion. (Lesson 6)
Kuiper Belt
The ring of asteroids and other celestial bodies located past the
orbit of Neptune (Lesson 30)
lanthanide series Metallic group of elements located below the periodic table
consisting of elements 57 through 71 (Lesson 9)
latitude
A line that runs east-west on a map and measures the distance
north or south from Earth's equator (Lesson 29)
lava
Fluid, molten rock that has risen to the Earth's surface through a
volcano or volcanic vent (Lesson 26)
law
A phenomenon in nature that has been proven to occur whenever
certain conditions are met; also the statement of the phenomenon
(Lessons 1, 6)
Law of
In a chemical reaction, matter cannot be created or destroyed. It
Conservation of is conserved. (Lessons 7, 12)
Mass
Law of
Conservation of
Mass and Energy
Law of
Conservation of
Momentum
Law of Universal
Gravitation
lever
light year
line graph
line of symmetry
liquid
lithosphere
longitudinal wave
loudness
low pressure
system
luminosity
luminous
lunar month
luster
magma
magnetic domain
magnetic field
magnetic force
magnetic poles
magnetic
variation
magnetosphere
Neither energy nor matter can be created or destroyed. They can
only be changed or transformed from one form to another.
(Lessons 7, 17)
When two objects collide in a closed system, the total momentum
of both the objects remains the same before and after the collision.
Any momentum lost by one object is equal to the momentum
gained by the other object. (Lesson 15)
Any two masses attract each other with a force equal to a constant
multiplied by the product of the two masses and divided by the
square of the distance between them. (Lessons 16, 30)
A bar that is free to pivot around a specific point; one of the six
simple machines (Lesson 18)
The distance that light can travel during one year; 9.5 x 10 12
kilometers (Lesson 31)
A diagram of lines made from connected data points that represent
change in a value (Lesson 4)
An imaginary line that divides a figure into two equal parts that are
mirror images of each other (Lesson 27)
State of matter that has a definite volume but no definite shape
(Lesson 6)
Layer of Earth formed by the crust and the upper mantle (Lesson
26)
A wave that causes the medium to vibrate in a motion that is
parallel to the direction of the wave (Lessons 20, 21)
A physical response to the intensity of sound (Lesson 21)
Weather condition that occurs in areas of low atmospheric pressure
and usually results in some degree of precipitation (Lesson 28)
Astronomy: the rate at which a star gives off energy (Lesson 31)
An object that gives off its own light (Lesson 22)
The time it takes the Moon to complete one full cycle of Moon
phases, from new Moon to new Moon (Lesson 29)
A physical property test that identifies how a mineral reflects light
(Lesson 27)
Molten, liquid rock of the lower mantle (Lesson 26)
An area that has a high number of electrons with magnetic fields
that align (Lesson 24)
Space surrounding a magnet that experiences the force of
attraction or repulsion of the magnet; a region of space that is
characterized by the presence of a magnetic force (Lessons 8, 22,
24, 30)
The force a magnet places on another magnet, magnetic material,
or moving charges (Lesson 24)
The regions where a magnet's force is the strongest; the points at
which the Earth's magnetic force is strongest (Lesson 24)
The difference in the location of the magnetic and geographic poles
at a given point (Lesson 24)
The magnetic field around Earth; it is strongest at the north and
south magnetic poles (Lesson 24)
main-sequence
The longest stage of a star's life cycle during which the star
phase
produces hydrogen fusion (Lesson 31)
malleable
Able to be bent, reshaped, and hammered without breaking
(Lessons 9, 10)
manipulated
A variable that is altered to cause change within another variable
variable
(Lesson 4)
mantle
The thickest of the Earth's layers, lies between the crust and the
core (Lesson 26)
mass
A measure of the amount of matter in an object; also, a measure
of an object's inertia (Lessons 5, 15, 16, 17)
mass number
The sum of protons and neutrons in the nucleus of an atom; also
called atomic mass (Lessons 8, 9, 25)
matter
Anything that has mass and takes up space (Lessons 5, 8, 24)
mean
The sum of all the data in a set divided by the total number of
pieces of data; a value midway between the values of other
quantities (Lesson 2)
mechanical
Ratio of output force to input force; the number of times a
advantage
machine increases, or multiplies input force (Lesson 18)
mechanical
Energy associated with everyday objects; the total amount of
energy
potential and kinetic energy in an object (Lessons 17, 23)
mechanical wave A disturbance in matter that carries energy from one place to
another (Lessons 20, 21, 22)
medium
pl. media; Matter through which a force acts or an effect is
produced (Lessons 20, 21, 22, 23)
melting
Phase change that occurs when a solid changes into a liquid
(Lesson 7)
melting point
Same as the freezing point; the temperature at which a solid
becomes a liquid and at which a liquid becomes a solid (Lesson 7)
mesosphere
One of the upper layers of the Earth's atmosphere (Lesson 28)
metal
Reactive element that is a good conductor of electricity and heat,
located to the left of the 'staircase' on the periodic table (Lesson 9)
metallic
Term used to describe a substance that is made of metal or carries
the properties of a metal (Lesson 10)
metallic bond
Bond formed between a metal cation and the shared electron
around it (Lesson 10)
metalloid
An element located along the 'staircase' on the periodic table that
exhibits properties of both metals and non-metals (Lesson 9)
metamorphic
A rock that is formed by changes to igneous or sedimentary rocks
rock
through heat and pressure (Lesson 27)
metamorphism
The process in which metamorphic rock is formed by changes in
exposure to heat and pressure (Lesson 27)
meteoroid
Debris that is produced when asteroids collide with one another
(Lesson 30)
meteorologist
A scientist who studies the atmosphere, including climate and
weather patterns (Lesson 28)
meter
The most basic unit of length in the metric system (Lesson 3)
metric system
The decimal system of weights and measures (Lesson 3)
mineral
A solid compound that is formed from one or more elements that
occur naturally (Lesson 27)
mineralogy
The scientific study of minerals (Lesson 27)
miscible
Capable of being mixed (Lesson 13, Lab 1)
mixture
Substance composed of two or more substances mixed together
(Lessons 5, 13)
Mohs' scale of
A scale that is used to rate the scratch resistance of a mineral
hardness
(Lesson 27)
molecular
The actual formula for a compound; shows the actual number of
formula
atoms in the compound and gives the types of atoms and the
exact number of each type (Lesson 11)
molecule
Smallest part of a compound that contains all chemical properties
of the compound; two or more atoms held together by chemical
bonds (Lessons 5, 10, 17, 23)
momentum
A property of mass that is moving; equal to the product of an
object's mass and velocity (Lesson 15)
motion
The act or process of changing position (Lesson 15)
natural magnet Substance found in nature that has magnetic properties (Lesson
24)
neap tide
The lower than average tide that is created when the Moon and the
Sun are at a right angle relative to the Earth (Lesson 29)
nebula
pl. nebulae; Collection of gas and dust particles found in space
(Lessons 26, 30, 31)
negative
A measure of a decrease in an object's velocity in the opposite
acceleration
direction as its motion (Lesson 15)
net charge
The overall charge of an object (Lesson 23)
net force
The sum of all the forces acting on an object (Lessons 15, 16)
neutral
Physics and chemistry: Having no electrical charge (Lesson 8)
Chemistry: Having neither acidic nor alkaline qualities (Lesson 14)
neutralization
A double displacement reaction between an acid and a base that
produces two neutral substances: salt and water (Lesson 14)
neutron
A particle of an atom that holds no charge; located in the nucleus
(Lessons 8, 23, 24)
newton
The force needed to move one kilogram at a rate of one meter per
second squared; the SI unit for force (Lesson 15)
Newton's First
Objects that are in motion will stay in motion unless they are acted
Law of Motion
upon by an outside force; objects that are not moving will stay still
unless they are acted upon by an outside force. (Lessons 15, 30)
Newton's Second The force acting on an object is equal to the product of the mass of
Law of Motion
the object and its acceleration. (Lessons 15, 16)
Newton's Third
For every force, there is an equal force in the exact opposite
Law of Motion
direction. (Lesson 16)
noble gas
An element from the group of non-reactive, non-metal elements
located in group 18 on the periodic table (Lesson 9)
nomenclature
A set or system of names or terms (Lesson 11)
non-foliated
Rock texture characterized by the absence of layered mineral
grains (Lesson 27)
non-metal
An element that is a poor conductor of heat and electricity; located
to the right of the 'staircase' on the periodic table (Lesson 9)
non-silicate
Minerals that do not contain bonded silicone and oxygen
tetrahedrons (Lesson 27)
nuclear radiation Charged particles and energy given off by the nuclei of
radioisotopes as they decay (Lesson 25)
nuclear reactor
A device in which a nuclear chain reaction can be initiated,
sustained, or controlled in order to generate heat and power
(Lesson 25)
nucleus
pl. nuclei; Chemistry: The dense core of an atom where the
protons and neutrons are located (Lessons 8, 10, 23, 24, 25)
Earth and Space Science: The hard, rocky center of a comet
(Lesson 30)
oceanic ridge
Chain of underwater volcanic mountains (Lesson 26)
octet rule
Atoms are happiest when their outer shell is filled with the
maximum number of valence electrons. (Lesson 10)
ohm
The unit of measurement for resistance (Lesson 23)
Ohm's Law
The voltage in a circuit equals the product of the current and the
resistance. (Lesson 23)
Oort cloud
A hypothetical region that exists past the Kuiper Belt and is
believed to be the region where long range comets originate
(Lesson 30)
opaque
Not permitting light to pass through at all (Lesson 22)
optics
The study of invisible and visible light and vision; the use of optical
technology (Lesson 22)
orbit
The path of a celestial body around another object (Lesson 29)
orbital
Space around the nucleus where the electrons are most likely to
be located (Lessons 8, 9)
order of
The step-by-step process by which equations are solved (Lesson 2)
operations
ore
A type of rock that contains a profitable amount of a metal mineral
(Lesson 27)
outer core
The liquid outside portion of the Earth's core (Lesson 26)
outermost shell The farthest orbital from the nucleus of an atom that still contains
electrons (Lesson 9)
output force
The force that a machine applies to an object; represented by F out
(Lesson 18)
output work
The work that is done by a machine; represented by Wout (Lesson
18)
ozone
One of the three forms of oxygen that help shield the Earth from
harmful ultraviolet rays in the atmosphere (Lessons 28, 30)
Pangaea
Name of the proposed landmass that was all of Earth's continents
before breaking apart and drifting (Lesson 26)
parallel circuit
An electric circuit with two or more paths through which current
can flow (Lesson 23)
parent rock
Igneous or sedimentary rock in its original state before
metamorphism takes place (Lesson 27)
particle
A small component of matter such as an atom, electron, or proton
(Lessons 8, 22)
penumbra
The part of a shadow where the light is not completely blocked
(Lesson 29)
perihelion
The point in a planet's orbit that is closest to the Sun (Lesson 29)
period
periodic table: Row of elements on the periodic table; there are
seven periods on the periodic table (Lesson 9)
waves: The time needed for one full cycle of periodic motion
(Lesson 20)
periodic table of Chart that lists all of the elements according to their properties
the elements
(Lesson 9)
permanent
Magnetized material that will not lose its magnetic properties
magnet
(Lesson 24)
pH
A measure of how acidic or basic a solution is (Lesson 14, Lab 2)
pH electrode
An electrical device that measures pH (Lesson 14)
pH meter
An electrical device that measures pH (Lesson 14)
pH scale
A scale that ranges in value from 0 to 14 that is used to measure
the pH of a solution (Lesson 14, Lab 2)
phase
A physical condition of a substance; also called state of matter
(Lessons 6, 19)
phase change
Process in which a substance changes from one state of matter to
another (Lesson 7)
phase change
A plot of temperature versus energy showing the various states of
diagram
a substance, the conditions under which each phase exists, and
the phase change that occurs between each state (Lesson 7)
phase diagram
A plot of temperature versus pressure showing the various phases
of a substance and the conditions under which each phase exists
(Lesson 7)
photon
A packet of electromagnetic energy (Lesson 22)
physical change Alteration of a physical property of a substance (Lessons 5, 7, 13)
physical property A characteristic of a substance that describes a type of physical
change it can undergo (Lesson 5)
pictograph
A graph or chart with symbolic figures that represent a certain
amount of data (Lesson 4)
pitch
Frequency of sound as perceived by a listener (Lesson 21)
planetary disk
Thin disk of dust, gas, and debris that surrounds a protostar
(Lesson 26)
plasma
State of matter in which the electrons have been removed from
atoms (Lessons 6, 25, 29, 31)
plate tectonics
The process by which the Earth’s plates continuously move over
top of the mantle (Lesson 26)
polar
A pair of opposite charges or poles (Lesson 13, Lab 1)
polarization
Behavior of light when the light waves vibrate in only one plane
(Lesson 22)
polyatomic ion
An ion that contains two or more atoms bonded together (Lesson
11)
porphyritic
A type of rock texture that has both large and small mineral
crystals (Lesson 27)
potential energy The energy between two objects due to their position relative to
each other (Lessons 17, 19, 23)
power
precipitate
precipitation
precision
pressure
product
projection
formula
property
proton
protostar
pulley
pure substance
qualitative
quantitative
quark
radiation
radioactive
radioisotope
rarefaction
rate
ratio
reactant
reaction
reaction rate
reactive
real image
redshift
The rate at which work is performed; the rate of energy transfer
over time (Lesson 18)
A solid that forms or separates itself from a solution as a result of
or during a chemical reaction (Lessons 5, 13)
The collective term for any form of water that falls to the Earth,
including rain, snow, and ice (Lessons 7, 28, Lab 4)
A measurement of how exact a value is (Lesson 3)
A force applied over an area (Lessons 6, 12)
Substance formed as a result of a chemical reaction (Lesson 12)
Formula that shows a three-dimensional structure in twodimensional form (Lesson 11)
A distinctive characteristic (Lesson 5)
A positively charged particle located in the nucleus of an atom
(Lessons 8, 14, 23, 24)
An early stage in the evolution of a star (Lessons 26, 31)
A wheel with a groove for a rope or chain; one of the six simple
machines (Lesson 18)
Matter that has a fixed composition (Lesson 5)
Having to do with the qualities, character, or behavior of
something (Lesson 1)
Having to do with numbers, measurement, or the amount of
something (Lesson 1)
A particle of matter that is theorized to be one of the basic units of
matter (Lesson 8)
The transfer of energy by waves that move through space (Lesson
19)
Property of certain elements or isotopes of an element whose
atomic nucleus is unstable and can emit charged particles (Lessons
9, 25)
An atom that has an unstable nucleus; also called a radioactive
isotope (Lesson 25)
The area in a longitudinal wave in which the particles in the
medium are spread out (Lessons 20, 21)
A comparison of two values where one is divided by the other
(Lessons 2, 15, 16, 18)
A comparison of two numbers using division; often represented by
a fraction (Lesson 11)
Substance that undergoes change when a chemical reaction occurs
(Lessons 12, 13)
A process by which one substance is transformed into another; a
process in which a chemical change occurs (Lesson 9)
How quickly reactants turn into products; speed at which a
reaction occurs (Lesson 12)
Readily or easily able to undergo a chemical change (Lesson 9)
An image that is formed at the point where light rays meet (Lesson
22)
A shift to longer wavelengths emitted by a celestial body that
indicates the object is moving away from Earth (Lessons 22, 31)
reference point
reflection
refraction
regular reflection
repulsion
resistance
responding
variable
resonance
rest position
reversible
reaction
revolution
rift valley
rock
rock cycle
rotation
salt
satellite
saturated
solution
scattering
Scientific Method
scientific notation
screw
sedimentary rock
semiconductor
An indicator used to orient further data; a point that is chosen to
represent zero when calculating a change in a value (Lessons 17,
19)
The return of a wave after striking a surface through which it
cannot pass (Lessons 20, 21, 22)
The bending of a wave as it enters a new medium (Lessons 20, 21,
22, 29)
Type of reflection that occurs when parallel light waves strike a
surface and bounce off in the same direction (Lesson 22)
The force that acts between like bodies of electric or magnetic
charges to separate them; pushes away (Lessons 23, 24)
The property of a conductor that works against the passage of
current (Lesson 23)
A variable that changes as a direct result of the manipulated
variable (Lesson 4)
The state in which one object vibrates at or near the frequency of
another, causing the second object to vibrate (Lessons 20, 21)
The position of a medium when no energy is traveling through it
(Lesson 20)
Chemical reaction in which forward and backward (reverse)
reactions can take place at the same time (Lesson 12)
One complete voyage of a celestial body around its point of orbit
(Lesson 29)
Valley created when the plate under a continent is stretched until it
breaks and then sinks (Lesson 26)
A mass composed of one or more minerals as well as rock
fragments and volcanic glass (Lesson 27)
The circular process of creating and recycling rock material that
has no beginning and no end (Lesson 27)
The spin of a celestial body on its axis (Lesson 29)
A product of a neutralization reaction; any ionic compound
composed of cations and anions that has an overall neutral charge
(Lesson 14)
An object in the solar system that orbits the Sun or a planet
(Lessons 29, 30)
A solution that contains as much dissolved solute as possible under
normal condition and at a given temperature (Lesson 13)
Behavior of light when light is redirected as it passes through a
medium (Lesson 22)
A method of research and experimentation for gathering,
organizing, and sharing scientific information (Lesson 1)
A way to express very large or small numbers as a number
multiplied by a power of 10 (Lesson 2)
An inclined plane wrapped around a cylinder; one of the six simple
machines (Lesson 18)
A rock that is formed from the buildup and compression of
sediments over time (Lesson 27)
A substance in which its ability to conduct heat and electricity falls
between conductors and insulators and is only effective under
certain conditions; a substance able to conduct heat and electricity
better than non-metals but not as well as metals (Lesson 9)
series circuit
A circuit in which all of the parts of the electrical circuit are set up
in one closed loop (Lesson 23, Lab 3)
shell
Specific path or space within an atom where the electrons are
most likely to be located; also known as an energy level or orbital
(Lesson 9)
sidereal month
The time it takes the Moon to revolve around the Earth once and
reach the same place in the sky relative to the stars behind it
(Lesson 29)
significant figure Every digit that is known in a measurement (Lesson 3)
silicate
A group of minerals in which all the minerals contain bonded
silicone and oxygen tetrahedrons (Lesson 27)
simple machine A tool that only requires one force to be applied for it to do work
(Lesson 18)
simplest form
When the numerator and denominator have no common factor
except for 1 (Lesson 2)
single bond
Type of bond formed when atoms share only one pair of electrons
(Lesson 10)
single
Chemical reaction that occurs when one element replaces another
replacement
element in a compound (Lesson 12)
reaction
solar wind
The flow of gas and charged particles from the Sun into space that
forms the heliosphere (Lesson 30)
solid
State of matter that has a definite volume and shape (Lesson 6)
solidification
The process by which magma hardens and forms igneous rock
(Lesson 27)
solstice
The time when the Earth is tilted the most either towards or away
from the Sun; there are two solstices every year (Lesson 29)
solubility
Ability of one substance to dissolve in another substance; physical
property that measures the maximum amount of solute that can
be dissolved in a specific amount of solvent (Lesson 13, Lab 1)
soluble
Capable of being dissolved (Lessons 11, 13, Lab 1)
solute
In a solution, the substance that gets dissolved (Lesson 13, Lab 1)
solution
Two or more different substances combined to form a
homogeneous mixture (Lessons 11, 13, Lab 1)
solvent
In a solution, the substance in which another substance is
dissolved (Lesson 13, Lab 1)
sonic boom
An explosion-like sound (as perceived from the ground) that is the
result of the shock wave created by an aircraft flying faster than
the speed of sound (Lesson 21)
specific heat
The amount of heat necessary to raise the temperature of one
gram of a material by one degree Celsius (Lesson 19)
spectator ion
An ion that is present during a chemical reaction but does not
participate in the reaction (Lesson 14)
speed
The rate of change in position over time (Lesson 15)
spontaneous
A natural process that occurs on its own without any help;
spring tide
stable
star
state of matter
static electricity
static friction
steam
stratosphere
storm surge
streak
strong acid
strong base
strong nuclear
force
structural
formula
unplanned (Lesson 12)
The higher tidal levels created when the Moon and the Sun are on
opposite sides of the Earth (Lesson 29)
Nonreactive; resistant to chemical change (Lessons 9, 10)
A mass of self-luminous gas (Lesson 31)
A physical condition of a substance; phase (Lesson 6)
A stationary electric charge that builds up in an insulated material
(Lesson 23)
Friction that cannot be overcome by applying a force on an object
(Lesson 15)
Gaseous state of water, produced when water is heated to its
boiling point and changes from a liquid to a gas (Lesson 7)
The second layer of the Earth's atmosphere (above the
troposphere); contains the ozone layer (Lesson 28)
A significant rise in sea level at the coastline, caused by the winds
of a cyclone (Lesson 28)
A physical property test that identifies the color of a mineral in
powder form (Lesson 27)
An acid that completely dissociates in water (Lesson 14)
A base that completely dissociates in water (Lesson 14)
The force of attraction that binds protons and neutrons together in
the nucleus (Lesson 25)
Formula that shows how atoms are arranged within a molecule or
ion; shows the bonding of atoms and ions and which elements are
bonded to each other (Lesson 11)
A unit of matter smaller than an atom (Lesson 8)
subatomic
particle
subduction zone Collision of Earth's plates that results in one plate overlapping
another (Lesson 26)
subscript
Smaller numbers or letters set partly below the normal text
(Lessons 11, 25)
sublimation
Phase change that occurs when a solid is converted directly into a
gas, skipping the liquid phase (Lesson 7)
supercell
A type of thunderstorm in which the winds rotate; can lead to the
formation of a tornado (Lesson 28)
superconductor A conductor with almost zero resistance at very low temperatures
(Lesson 23)
supergiant
An exceptionally large star whose diameter is more than 100 times
that of the Sun (Lesson 26)
supernatant
Liquid portion of a solution or suspension that remains after a
precipitate has settled to the bottom of the container (Lesson 13)
supernova
pl. supernovae; The last stage in the cycle of a star (Lessons 22,
26, 30, 31)
supersaturated
A solution containing more than the maximum amount of solute
solution
that can normally be dissolved in a solvent at a given temperature
(Lesson 13)
superscript
Smaller numbers or letters set partly above the normal text
(Lessons 11, 25)
surface area
The amount of exposed area an object has; the total area of the
outside of a three-dimensional shape or a two-dimensional figure
with a closed boundary (Lessons 13, 29)
surface wave
A wave that travels along a surface between two media (Lessons
20, 21)
suspension
A heterogeneous mixture that separates into its parts over time
(Lesson 13)
symbol
Shorthand or abbreviation used to represent something else
(Lesson 9)
synodic month
The time it takes the Moon to complete one full cycle of Moon
phases, from new Moon to new Moon; also called a lunar month
(Lesson 29)
synthesis
Chemical reaction that occurs when two or more substances
reaction
combine to form a single compound; also called a combination
reaction (Lesson 12)
tectonic
The most common type of earthquake; occurs along plate
earthquake
boundaries (Lesson 26)
temperature
A measure of how hot or cold something is when it is compared to
a reference point (Lesson 19)
temporary
Magnetized material that can lose its magnetic properties (Lesson
magnet
24)
terminal velocity The point at which a falling object stops accelerating because the
force of air resistance equals the force of gravity (Lesson 16)
terrestrial planets The four silicate rich, inner planets of the solar system: Mercury,
Venus, Earth, and Mars (Lesson 30)
texture
The description of the size and arrangement of a rock's geometric
composition (Lesson 27)
theory
A general proposition or group of propositions that explain a
phenomenon (Lesson 1)
thermal
Material that conducts heat energy well (Lesson 19)
conductor
thermal
Contraction of a substance due to a loss of heat (Lesson 19)
contraction
thermal energy A measure of the kinetic energy of molecules and atoms in an
object (Lessons 17, 19)
thermal
A characteristic of matter that causes particles of matter to move
expansion
farther apart when the temperature increases, therefore the
substance takes up more space as it gets hotter (Lessons 6, 19)
thermal insulator Material that does not conduct heat energy well (Lesson 19)
thermodynamics The study of conversion of thermal energy into other forms of
energy (Lesson 19)
thermosphere
The region of the upper atmosphere in which temperature
increases; includes all of the atmosphere above the mesosphere
(Lesson 28)
thunderstorm
A violent storm of thunder or lightning, usually accompanied by
rain and sometimes hail (Lesson 28)
tide
The daily rise and fall of ocean waters, created by the Moon's
gravity and other forces (Lesson 29)
tornado
total internal
reflection
totality
transform plate
boundary
transformer
transition metal
translucent
transmission line
transparent
transpiration
transverse wave
trench
triple bond
triple point
Tropic of Cancer
Tropic of
Capricorn
troposphere
trough
Tyndall effect
ultrasound
umbra
unbalanced force
universal solvent
universe
unsaturated
Concentrated storms that are characterized by a funnel-shaped
cloud and extreme winds (Lesson 28)
The complete reflection of a light ray back into its original medium
(Lesson 22)
The period of time in an eclipse when the Sun or Moon is
completely covered by the body passing in front of it (Lesson 29)
Plate movement in which two plates slide past each other in
opposite directions and plate material is neither produced nor
destroyed (Lesson 26)
An electric device that increases or decreases voltage in AC circuits
(Lesson 23)
An element belonging to groups 3 through 12 of the periodic table
(Lessons 9, 11)
Permitting some light to pass through but diffusing it so that
objects on the other side appear distorted or blurry (Lesson 22)
High voltage electrical wiring that carries a signal (such as
electricity) long distances (Lessons 23, 24, 25)
Any material that lets all or almost all visible light pass through
(Lessons 13, 22)
Evaporation of water through a plant from the roots, through the
vascular system, and into the atmosphere (Lesson 7)
A wave that causes the medium to vibrate in a motion that is
perpendicular to the direction of the wave (Lessons 20, 21, 22)
A deep valley in the ocean floor created when Earth's plates collide
(Lesson 26)
Type of bond formed when atoms share three pairs of electrons
(Lesson 10)
The temperature and pressure at which all three phases of matter
(solid, liquid, and gas) are present (Lesson 7)
The point farthest north on Earth where the Sun will ever be
directly overhead (Lesson 29)
The point farthest south on Earth where the Sun will ever be
directly overhead (Lesson 29)
The lowest layer of the Earth's atmosphere; about 10km from the
Earth's surface (Lesson 28)
The lowest point of a transverse wave below the rest position
(Lesson 20)
The scattering of light passing through a colloid (Lesson 13)
Sound with frequencies too high to be heard by the human ear
(Lesson 21)
The part of a shadow where the light is completely blocked (Lesson
29)
A net force that is greater than or less than but not equal to 0 N in
a system; unbalanced forces create acceleration (Lesson 15)
A liquid that can dissolve almost anything, i.e. water (Lesson 13,
Lab 1)
All of the matter that physically exists (Lesson 31)
A solution that can dissolve more solute at a given temperature
solution
updraft
vacuum
(Lesson 13)
Fast-moving warm air (Lesson 28)
A space that is entirely devoid of matter (Lessons 8, 15, 17, 19,
22, 28, 30)
valence electron Electron within the outermost shell, or valence shell, of an atom
(Lessons 9, 10, 11)
valence shell
Outermost shell of an atom (Lesson 9)
vapor
Gaseous state of a substance that is a solid or liquid at ordinary
temperatures (Lessons 7, 28)
vaporization
Phase change that occurs when a liquid changes to a gas (Lesson
7)
variable
Something that is capable of being varied or changed (Lessons 1,
4)
velocity
Change in position over time in a defined direction (Lessons 15,
16, 17)
vesicular
A type of rock texture that is characterized by the presence of
holes that formed from air bubbles during the hardening of magma
(Lesson 27)
virtual image
A copy of an image that is formed at the place from where the
light rays seem to come (Lesson 22)
visible spectrum The range of wavelengths that are visible to the human eye
(Lesson 22)
volcanic
Earthquakes that result from the pressure placed on the Earth's
earthquake
crust when magma pushes through the Earth's interior (Lesson 26)
volcano
A vent in the Earth's crust through which lava, steam, and ashes
are expelled (Lesson 26)
voltage
The difference in electrical potential energy between two places in
an electric field; also known as potential difference (Lesson 23)
volt
The SI unit of measurement for voltage (Lesson 23)
volume
Amount of space occupied by an object (Lesson 5, 29)
waning
When the Moon is going from full to new, or appearing to shrink
(Lesson 29)
water
Moving or putting water out of its original place (Lesson 5)
displacement
water cycle
The path water takes through its different states (solid, liquid, and
gas), which is a never-ending movement of water between the
sea, the land, and the air (Lessons 7, 28, Lab 4)
wave
A disturbance that transmits energy from point to point through
matter or space (Lessons 8, 20, 21)
wavelength
The distance from the peak of one wave to the peak of the next
(Lesson 20)
waxing
When the Moon is going from new to full, or appearing to grow
(Lesson 29)
weak acid
An acid that only partially dissociates in water (Lesson 14)
weak base
A base that only partially dissociates in water (Lesson 14)
weather
The condition of the atmosphere over a limited area and time
period (Lesson 28)
weather front
The boundary where a difference in air mass density causes the air
weather map
weather symbol
weathering
wedge
weight
wheel and axle
white light
work
x-axis
y-axis
regions to interact and move (Lesson 28)
Tool for showing patterns in weather and air movement (Lesson
28)
A picture on a weather map that represents a specific weather
condition (Lesson 28)
The processes that cause exposed rock to break down (Lesson 27)
A movable, V-shaped inclined plane; one of the six simple
machines (Lesson 18)
A measure of the force of gravity acting on an object; calculated
by multiplying an object’s mass by gravity (Lessons 5, 16)
A wheel that turns about a fixed point, the axle; one of the six
simple machines (Lesson 18)
Visible light, such as that given off by the Sun (Lesson 22)
A force that causes an object to move in the direction of the force;
a change in energy (Lessons 17, 18, 19, 25)
The horizontal line on a graph (Lessons 4, 7, 15)
The vertical line on a graph (Lessons 4, 15)