8th Grade Science Content Vocabulary
Energy and Matter Key Terms
Atom - the smallest particle of an element that can exist either alone or in combination
Element - A substance which cannot be separated into smaller parts and still retain its chemical
identity. For example, sodium (Na) is an element.
Compound - a substance made up of two or more elements.
Energy Transformations - The process of changing from one energy form to another
Kinetic Energy - Energy due to motion of a mass
Law of Conservation of Energy - basic law of nature which claims that energy is neither
created nor destroyed but rather changes form
Mass - The measurement of the amount of matter that an object contains.
Metal - A substance that is a good conductor of electricity and heat. They also have the
properties of being ductile, malleable and shiny
Metalloid - A substance that has some properties of metals and some properties of nonmetals
Mixtures - a material made up by two or more different substances which are mixed but are not
combined chemically
Nonmetal - A substance that lacks the properties of a metal which are brittle and are poor
conductors of heat and electricity
Potential Energy - A form of energy that can be converted to other, more useful forms; stored
energy
Radioactive - a property of an element that causes it to spontaneously decay into other smaller
elements
Weight - The mathematical relationship between mass and gravitational pull; Weight = Mass x
Gravity
Battery- A small cell that contains chemicals that create a charge when they react with one
another.
Chemical Potential Energy - Potential energy held in the chemical bonds of a substance
Combustion Reaction- A reaction that occurs between a fuel source and oxygen where water
and Carbon dioxide are produced.
Elastic Potential Energy - Potential energy stored in elastic or compressive materials
Energy- The ability to do work
Kinetic Energy - The energy of motion
Magnetic Potential Energy - Potential energy stored in magnetic substances
Mechanical Energy - Energy involve with moving or displacing objects.
Photoelectric Cell - A specialized metal contained in a cell that can convert sunlight into
electrical energy.
Potential Energy - Stored Energy
8th Grade Science Content Vocabulary
Force Key Terms
Acceleration - The change in velocity over time. If an object is speeding up it is said to have
positive acceleration; if it is slowing down it is said to have (negative acceleration).
Compound machine – Two or
more simple machines that work together for a common
function
Force - an influence that changes an objects motion, direction or geometrical arrangement
Friction - A force that acts in the opposite direction of movement based on the surfaces of the
materials that are interacting with one another
Gravity - A natural force that is directly proportional to an object’s mass
Inclined plane – An elevated flat surface that allows movement in the vertical direction while
also moving in the horizontal direction. Ex. A ramp
Inertia - The tendency of an object to remain at rest or remain in motion unless acted upon
by an outside force
Lever- A solidbar that pivots on an object called a fulcrum that gives a person a mechanical
advantage
Newton’s first law of motion- An object at rest will remain at rest unless acted on by an
unbalanced force.
Newton’s second law of motion – The mass of an object is inversely proportional to the
acceleration; F=ma
Newton’s third law of motion – For every action there is an equal and opposite reaction
Pulley - A specialized wheel and axle that uses a grooved wheel and a cable to change the
direction of a force
Screw - An inclined plane wrapped around a central shaft that allows for vertical movement
Speed – The rate at which an object covers distance
Velocity - The rate at which an object covers distance plus the direction of the object
Wedge – Two inclined planes that are placed back to back that are used to Separate object or
stop the movement of an object.
Weight- A product of an object’s mass and the gravitational pull acting on that object.
Wheel and Axle – A round object that is attached to a central rod that pivots around a fixed
point
Air Resistance- Friction associated with the interaction of an object with the air
Coefficient of Friction - The quantity that expresses the frictional forces between two objects
Equilibrium - The point at which an object is at rest or moving with a constant velocity
Force - A push or pull on an object as it interacts with its environment
Inertia - The natural tendency for an object to remain at rest or to remain in motion
Kinetic Friction - The retarding force that acts upon a moving object in the opposite direction
Momentum- The product of mass and velocity
Net Force - The sum of all forces acting upon an object
Newton's First Law - An object at rest remains at rest, and an object remains in motion unless
acted upon by an outside force
Newton's Second Law - The force an object exerts is equal to the objects mass multiplied by the
objects acceleration
Newton's Third Law - For every action there is an equal and opposite reaction
Normal Force - A force acting in the opposite direction of another force.
Rolling Friction- Friction associated with one object rolling over another
Sliding Friction- Friction associated with one object sliding over another
8th Grade Science Content Vocabulary
Static Friction - The force opposing the movement of an object across a surface
Weight- An objects mass multiplied by the gravitational force acting upon it
8th Grade Science Content Vocabulary
Light & Sound Key Terms
Angle of incidence - The angle at which light hits a reflective surface
Angle of reflection - The angle at which light leaves a reflective surface
Diffraction - the apparent bending of waves around small obstacles and the spreading out of
waves past small openings
Electromagnetic radiation - Energy that moves as both a particle and a wave that can travel
through any medium
Electromagnetic spectrum - The range of all possible wavelengths of electromagnetic radiation
Fiber optics - Optical fibers that can carry light over long distances that are used in
communication and data transfer
Frequency - The number of waves that pass a given point in a certain amount of time
LASER - Light Amplification by Stimulated Emission of Radiation
Lens - an optical device which transmits and refracts light, converging or diverging the beam .
Mirror - A substance that can reflect light efficiently
Photon - a bundle of light energy that moves as both a particle and a wave
Primary colors - Colors that can be added or subtracted from one another to create other colors.
Red, Blue, Green, Cyan, Magenta and Yellow.
Prism - A substance that can refract white light separating it into its colored components
Reflection - The change in direction of a wave from the surface of a reflective material.
Refraction - the bending of a wave when it enters a medium where it's speed changes due to
differences in density.
Speed of light - The speed at which light travels in a vacuum. ( 3.00 x 108 m/s)
Wave particle duality - The dual nature of light that explains the wave and particle
characteristics that light exhibits.
Wavelength - The distance between two crests of a wave.
Acoustics - The science of sound: Study of the interaction between sound waves and objects
Amplification - Producing sounds that have more intensity than where they
were
originally produced
Compression – Moving molecules closer together as
in a gas
Compression wave (longitudinal wave) - A wave produced where molecules are pushed closer
together and then rebound to their normal position
Crest - The highest point of a transverse wave
Decibel - Unit of sound intensity
Density - The ratio of mass versus volume: D= m/V
Doppler Effect - When sound waves of an object moving relative to the observer take on a
different frequency than if they were stationary.
Frequency - The number of waves that pass a given point in a given amount of time.
Inner ear - Inner most
part of the ear that contains the cochlea and nerve endings
Intensity - The
loudness of sound
Mach I - An object reaches this point when it breaks the sound barrier
Medium- A substance that sound can travel through
Middle ear - The part of the ear that contains the ossicles (ear bones)
Outer ear - The part of the ear that receives sound input from the outside world
P wave - Primary compression wave that occurs during an earthquake
Pitch - The high or low effect of sound based on frequency
Rarefaction - The decompression of a compression wave
S wave - The transverse wave associated with an Earthquake
8th Grade Science Content Vocabulary
Seismograph - An instrument that records seismic waves
Sonic Boom - The release of a massive sound wave that occurs when an object breaks the sound
barrier
Sound barrier - The point at which an
object exceeds the speed of sound
Sound wave - A compression wave that carries energy to a natural or artificial device that can
detect pressure changes
Speed of sound - 343.2 meters per second or 1,126 ft/s. This is equivalent to 1,236 Kilometers
per hour or 768 mph
Supersonic - An object that can break the sound barrier
Tinnitus- Ringing or hissing in the ear as a result of listening to high frequency or high intensity
sounds
Trough - The lowest part of a transverse wave
Transverse wave - A wave that moves energy in one direction but travels in a path That
oscillates up and down in equal directions
Wavelength - The distance between two crests in a transverse wave or the distance between the
compressions of a compression wave.
8th Grade Science Content Vocabulary
Electricity & Magnetism Key Terms
Alternating Current - the flow of electric charge periodically reverses direction
Ampere - Unit that is a measurement of electric current
Battery - A device that can generate an electric current by creating a potential difference
between two poles.
Bioelectricity - Electrical currents produced by living organisms
Conductor - Any material that allows an electric current to flow
Current - The flow of charged particles through a conductor
Direct Current - Current that flows in one direction
Electric Circuit - The pathway that electrical current flows through
Electricity - The flow of charged particles through a conductor that has the ability to do work
Electromagnet- A temporary magnet created by an electric current moving through a coiled
wire.
Ferrous Metals - Metals that can be attracted to a magnet
Load - The power leaving an electrical component
Magnetic Field - The region around a magnet where influence by the magnet is present
Magnetism - A property of materials that respond to an applied magnetic field
Ohms Law - Voltage / Resistance = Current or I = V/r
Parallel Circuit - A circuit with more than one pathway for current flow
Permanent magnet - Substances that have permanent magnetic qualities
Resistor - A substance that resists the flow of electricity
Series Circuit - A circuit with only one pathway for current
Static Electricity- A difference in charge that builds between two objects that results in a
discharge of energy
Superconductor - a phenomenon of exactly zero electrical resistance and expulsion of magnetic
fields occurring in certain materials when cooled below a characteristic critical temperature.
Switch - A device that interrupts an electrical current
Temporary magnet - Substances that have temporary magnetic properties based on the
influence of electricity or other magnets
Volt - The unit of measurement that describes the potential difference in charge between two
points.