Vocabulary 2

opaque:completely blocking light from passing through.

transparent: letting all right throught,so than objects on the other side can be seen clearly.

translucent: letting only some light throught, so that objects on the other side appear blurry. 

polarization: allowing light vibrations to pass throught in only one direction.

refraction: the bending of light rays as they pass from one substance into another.

convex lens: a lens that curves outward (is thicker at the middle than at the edges) and brings-

concave lens: a lens that curves inward (is thicker at the edges than at the middle) and spreads light rays apart.

Vocabulary 16

desalination: getting fresh water from seawater.

water  cycle: the continuous movement of water between Earht´s surface and the air, changinng from liquid to gas to liquid.

ground water: water that seeps into the ground into spaces between bits of rock and soil.

water table: the top of the water filled spaces in the ground.     

aquifer: an underground layer of rock or soil filled with water.

spring: a place where groundwater seeps out of the ground.

well: a hole dug below the water table that water seeps into.

reservoir: a storage area for freshwater supplies.

Vocabulary 15

renewable resource: a resource that can be replaced in a short period of time.

ozone layer: a layer of ozone gas in the atmosphere that screens out much of the Sun´s UV rays.

fossil fuel: a fuel formed from the decay of ancient forms of life.

smog: a mixture of smoke and fog.

acid rain: moisture  that falls to Earth after being mixtured with wastes from burned fossil fuels.

vocabulary 10

kinetic energy: the energy of a moving object.

potential energy: enrgy stored in a object or material.

conduction: movement of energy from a hot object that comes into contact with a cooler object; the material remains in place.

convection: movements of energy by the flow of matter from place to place.

radiation: movement of energy in the form of waves that can travel though empty space.

wet cell battery: a batery containing liquid solution that produces the electricity current.

dry cell battery: a battery that uses"dry chemicals" to produce an electric current.

Vocabulary 9

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

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

chemical reaction: a chemical change of  original substances  into one or more new substance.

reactant: one of the original substances beforce a chemical reaction takes place.

product: one of the new substances produced when a chemical reaction takes place.

vocabulary 8

mixture: two or more parts blended together yet keeping their own properties and not turning into a new substance.

solution: a mixture in wich substances are completely blended so that the properties are the same throughout and the substances stay blended so that the properties are the same throughout and the substances stay blended.

suspension: a mixture of substances that separate upon standing.

colloid: particles (or droplets) large enough to block out light spread throughout another substance.

emulsion: a liquid spread through another liquid.

aerosol: liquid drops of solid particles spread as a gas.

gel: a solid spread throuh a liquid.

foam: a gas spread through a liquid or solid.

vocabulary 7

State of Matter: any of the forms matter can exist in.

melting point: the temperature at wich a solid changes state into a liquid.

boiling point: the temperature at wich a liquid changes state into a gas.

freezing point: the temperature at wich a liquid changes state into a solid.

vocabulary 6

element: a basic building block of matter; a pure substance that cannot be broken down into anything simpler.

compound: a chemical  combination of two or more elements into a single substance.

atom: the smallest unit of an element that still has the properties of the elements.

proton: a particle with a positive charge in the nucleus of an atom.

neutron: an uncharged particle in the nucleus of an atom.

electron: a particle with a negative charge moving around the nucleus of an atom.

nucleus: the dense center part of an atom.

molecule: a group of more than one atom joined together that acts like a single particle.