Sources of energy

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 spliting 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

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 vaporization of molecules from the surface of a liquid.

Chemical changes

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 elctrons.

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

Chemical property: a way of describing how a substance changes chemically with other substances.

Exothermic: a reaction that gives off energy.

Endothermic: a reaction that absorbs heat. 

Temperature and Heat

Temperature and heat

Kinetic energy: the energy of a moving object.

Potential energy: energy that is 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.



Elements and Atoms

Elements and Atoms

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

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



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

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.

Physical Properties

Physical Properties

Matter:Any solid, liquid, or gas.

 Mass:Amount of matter in an object.

Volume:The amont of space an object takes up.

Density:The amount of mass in a certain volume of material.

Physical Property:A property that can be observed without changing the identity of a substance.

Physical Change:A change in size, shape, or state without forming a new substance.

Solution:A mixture of one substance dissolved in another so that the properties are the same throughout.

Chemical Change:A change in matter that produces a new substance with different proprties from the original.