Sources of Energy

Solar cell: 

A device that generates an electric current from sunlight.

biomass conversion:

Getting energy from plant and animal materials by changing them into high quality fuels.

nuclear fission:

The splitting of a nucleus with a large mass into two nuclei with smaller masses.

chain reaction: 

A reaction that is kept going by products of the reaction.

nuclear fusion: 

The merging of nuclei with smaller masses into a nucleus with a larger mass.

hydroelectricity: 

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 a liquid into a solid.

boiling:

the formation of bubbles of vapor that scape from a liquid that is being heated.

evaporation: 

the vaporation of molecules from the surface of a liquid.

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 electrically 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 substances.

exothermic: A reaction that gives off heat.

Endithermic:

                                  

                          A reaction that absorbs heat.

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 ofvenergy 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 a gas.

Insulation: 

prevents heat from flowing in or out of a material.

Elements and Atoms

element:a substance that cannot be broken down any further into anythyng 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 of a group of elements that conduct heat and electricity, is shiny and bendable.

Physical Properties

1.matter: any solid, liquid or gas.


2. mass: a measure of how hard it its to push or pull an object.



3.volume: the amount of space an object takes up.

 

4. density: the amount of mass in a certain volume of material.

5.physcal properties: a property that can be observed without changing the identity of a substance.

6.physical change: a change in size, shape, or state without forming a new substance.

7.solution: a mixture one substance dissolved in another so that the properties are the same throughout.

8.chemical change: a change in matter that produces a new substance with different properties from the original.