When Will Time End?

Source of Energy

Solar cell: a device that generates an electric current from sunlight.


Biomas conversion: getting energy from plant and  animal materials by changing them into high quality fuels.


Nuclear fission: The splitting of a nucleus with smaller masses.



Chain reaction: a reaction that is kept going by products of the reaction.

Nuclear fusion: the meging of nuclei with smaller masses into a nucleus with a larger mass.

Hydroelecricity: the use of flowing water to generate electricity.

Thermal pollution: the excess heating of the environment.



Temperature, Heat, and Matter

Thermal expansion: the expansion of matter when its temperature is raised.


pressure: the force on each unit of area of a surface.


melting: the change of a solid into a liquid.


vaporization: the change of a liquid to a gas as molecules break free from each other.


condensation: the change of a gas into a liquid as molecules attract each other.

freezing: the change of liquid into a gas.


boiling: the formation of bubbles of vapor that escape from a liquid that is being heated.


evaporation: the vaporization of molecules from the surface of a liquid.

SOUND

Pitch

This is how high or low a sound seems. A bird makes a high pitch. A lion makes a low pitch.

Sounds also are different in how loud and how soft they are.
The more energy the sound wave has the louder the sound seems.




 You can hear loud and soft sounds.We can do noise by example:play a drum,scream.
                        


see more in http://www.mediacollege.com/audio/01/sound-waves.html
put START and you will see the saound waves...LEARN MORE!

Temperature and Heat

Kinetic energy:the energy of a moving object.


potential energy: energy stored in an object or material.


temperature: the average kinetic energy of the molecules in a material.


heat: energy that flows between objects that have different temperatures.


radiation: the transfer of energy by electromagnetic waves.


conduction: the transfer of energy by direct contact of molecules.


convection: the transfer of energy by the flow of a liquid or gas.


insulation: prevents heat from flowing in or out of a material.

Chemical Changes

Compound: A chemical combination of two or more elements.


Chemical bond: A link that atoms or electrically charged particles can form with each other.


Chemical Formula: A way of using letters and numbers to show how much of each element is in a substance.


ion: An elecrocally charged particle with unequal numbers of protons and electrons.


Molecule: A group of bonded atoms that acts like a single particle.


Chemical Property: A way of describing how a substance changes chemically with other substance.


Exothermic: A reaction that gives off heat.


Endothermic: A reaction that absorbs heat.

Elements and Atoms

Element: a substance that cannot be broken down any further into anything simpler.




Atom: The smallest particle of an element that has the same chemical properties as the element.





Nucleus: An atom's dense center, where most of its mass is.




Electron: a negatively charged particle that moves around an atom's nucleus.




Proton: a positively charged particle inside an atom's nucleus.




Neutron: a particle with no charge inside an atom's nucleus.



Atomic number: the number of protons in an atom.




Metal: any group of elements that conduct heat and electricity, is shiny and bendable.