Earth and Physical Science 9th grade final
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133 terms
Terms | Definitions |
|---|---|
 Periodic Law | the law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements |
| Period | a horizontal row of elements in the periodic table |
| Group | a vertical column of elements in the period table |
| Ion | a particle that is electrically charged (positive or negative) |
| Metal | an element that is shiny and that conducts heat and electricity well |
| Nonmetal | an element that conducts heat and electricity poorly |
| Semiconductor | an element or compound that conducts electric current better than an insulator does but not as well as a conductor does |
| Alkali metal | one of the elements of Group 1 of the Periodic table |
| Alkali-Earth Metal | an element in group two of the periodic table |
| Transition metal | An Element in group 3 through 12 of the periodic table, one of the metals that can use the inner shell before using the outer shell to bond |
| Noble gas | an element in group 18 of the periodic table |
| Halogen | an element found in group 17 of the periodic table |
| Chemical Bond | the attractive force that holds atoms or ions together |
| Chemical Structure | the arrangement of atoms in a substance |
| Bond length | the average distance between the nuclei of two bonded atoms |
| Bond angle | the angle formed by two bonds to the same atom |
| Ionic Bond | the attractive force between oppositely charged ions, which form when electrons are transferred from one atom to another |
| Covalent Bond | a bond formed when atoms share one or more pairs of electrons |
| Metallic Bond | a bond formed by the attraction between positively charged metal ions and the electrons around them |
| Polyatomic Ion | an ion made of two or more atoms |
| Empirical Formula | the composition of a compound in terms of the relative numbers and kinds of atoms in the simplest ratio |
| Molecular Formula | a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms. |
| Organic Compound | a covalently bonded compound that contains carbon, excluding carbonates and oxides |
| Polymer | large molecule formed when many smaller molecules bond together |
| Reactant | a substance or molecule that participates in a chemical reaction |
| Product | a chemical substance formed as a result of a chemical reaction |
| Chemical Energy | the energy released when a chemical compound reacts to produce new compounds |
| Exothermic reaction | chemical reaction in which energy is primarily given off in the form of heat |
| Endothermic Reaction | A chemical reaction that requires energy input |
| Chemical Equation | a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products |
| Mole Ratio | the relative number of moles of the substances required to produce a given amount of product in a chemical reaction |
| Acid | any compound that increases the number of hydronium ions when dissolved in water |
| Indicator | a compound that changes color in the presence of an acid or a base |
| Electrolyte | a substance that dissolves in water to give a solution that conducts electric current |
| Base | Any compund that increases the number of hydroxide ions when dissolved in water |
| pH | a value that indicated the acidity or alkalinity of a solution on a scale of 0-14, based on the proportion of H+ ions. |
| Neutralization reaction | the reaction of an acid and a base to form a neutral solution of water and a salt |
| Salt | an ionic compound that forms when a metal atom or a positive radical replaces the hydrogen of an acid |
| Radioactive Decay | the disintegration of an unstable atomic neceus into one or more different nuclides |
| Nuclear Radiation | the particles that are released from the nucleus during radioactive decay |
| Alpha Particle | a positively charged particle that is the nucleus of the helium atom |
| Beta Particle | an electron emitted from the nucleus during some kinds of radioactive decay |
| Gamma Ray | the high-energy photon emitted by a nucleus during fission and radioactive decay |
| Half life | the time required for one half of the atoms of a radioisotope to emit radiation an decay products |
| Fission | the process by which a nucleus splits into two or more fragments and releases neutrons and energy |
| Nuclear chain reaction | A continuous series of nuclear fission reactions. |
| Critical Mass | the minimum mass of fissionable material that can sustain a chain reaction |
| Fusion | the process in which light nuclei combine at extremely high temperatures, forming heavier nuclei and releasing energy |
| Radioactive tracers | radioactive atoms that are incorporated into substances so that movement of the substances can be followed by radiation detectors |
| Sound Wave | a longitudinal wave that is caused by vibrations and that travels through a material medium |
| Pitch | a measure of how high or low a sound is perceived to be |
| Infrasound | slow vibrations of frequencies lower than 20 Hz |
| Ultrasound | sound waves with frequencies above 20,000 Hz |
| Resonance | a phenomenon that occurs when two objects naturally vibrate at the same frequency |
| Sonar | sound navigation and ranging uses echoes to determine locations |
| Photon | a unit or quantum of light |
| Intensity | the rate at which a wave's energy flows through a given unit of area |
| Radar | radio detection and ranging |
| Light Ray | a line in space that matches the direction of the flow of radiant energy |
| Virtual Image | an image that forms at a location from which light rays appear to come but do not actually come. |
| Real Image | an image of an object formed by light rays that actually come together at a specific location |
| Lens | a transparent optical device used to converge or diverge transmitted light and to form images |
| Magnification | the increase of an object's apparent size by using lenses or mirrors |
| Prism | in optics, a system that consists of two or more plane surfaces of a transparent solid at an angle with each other |
| Dispersion | in optics, the process of separating a wave of different frequencies into its individual component waves |
| Electric Charge | an electrical property of matter that creates electric and magnetic forces and interactions |
| Electrical Conductor | a material in which charges can move freely |
| Electrical insulator | a material in which charges cannot move freely |
| Electric force | The force of attraction or repulsion on a charged particle that is due to an electric field |
| electric Field | The space around a charged object in which another charged object experiences an electric force |
| Electrical Potential Energy | the ability to move an electric charge from one point to another |
| Potential Difference | the voltage difference in potential between two points in a circuit |
| Cell | a device that delivers an electric current as the result of a chemical reaction |
| Electric Current | The rate at which charges pass a given point |
| Resistance | the opposition to the flow of electric charge |
| Electric Circuit | a set of electrical components connected such that they provide one or more complete paths for the movement of charges |
| Schematic Diagram | a graphical representation of a circuit that uses lines to represent wires and different symbols to represent components |
| Series Circuit | a circuit having its parts connected serially |
| Parallel Circuit | A circuit in which the parts are joined in branches such that the potential difference across each part is the same |
| Electric Power | the rate at which electrical energy is converted to another form of energy |
| Fuse | an electrical device that contains a metal strip that melts when current in the circuit becomes too great |
| Circuit Breaker | a switch that opens a circuit automatically when the current exceeds a certain value |
| Magnetic Pole | the ends of a magnetic object, where the magnetic force is strongest |
| Magnetic Field | a region where a magnetic force can be detected |
| Solenoid | a coil of wire around an iron core |
| Electromagnet | A coil that has a soft iron core and that acts as a magnet when an electric current is in the coil |
| Electric Motor | a device that converts electrical energy into mechanical energy |
| Galvanometer | an instrument that detects, measures, and determines the direction of a small electric current. |
| Electromagnetic Induction | the process of creating a current in a circuit by changing a magnetic field |
| Generators | a device that changes mechanical energy into electrical energy. |
| Alternating Current | an electric current that reverses direction sinusoidally |
| Transformer | a device that increases or decreases the voltage of alternating current |
| Planet | any of the celestial bodies (other than comets or satellites) that revolve around the sun in the solar system |
| Solar System | sun, planets, and all the other objects that revolve around the sun |
| Satellite | any celestial body orbiting around a planet or star |
| Phase | (astronomy) the particular appearance of a body's state of illumination (especially one of the recurring shapes of the part of Earth's moon that is illuminated by the sun) |
| Eclipse | an event in which the shadow of one celestial body falls on another |
| Terrestrial Planet | one of the highly dense planets nearest to the sun; mercury, venus, mars, and earth |
| Hydrosphere | the portion of earth that is water |
| Asteroid | a small, rocky object that orbits the sun; most asteroids are located in a band between the orbits of Mars and Jupiter |
| Dwarf Planet | a large, round object that revolves around the sun but has not cleared the region around its orbit |
| Gas Giant | A large planet that consists mostly of gases in a dense form. The four large planets in the outer solar system- Jupiter, Saturn, Uranus, and Neptune. |
| Nebular Hypothesis | a model for the formation of the solar system in which the sun and planets condense from a cloud (or nebula) of gas and dust |
| Comet | a small body of ice, rock, and cosmic dust that follows an elliptical orbit around the sun and that gives off gas and dust in the form of a tail as it passes close to the sun |
| Exoplanet | a planetlike body that orbits a star other than the sun |
| Star | (astronomy) a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior |
| Light Year | light distance travels in one year (9.5 trillion km) |
| Red Giant | A large, reddish star late in its life cycle |
| White Dwarf | a small, hot, dim star that is the leftover center of an old star |
| Supernova | a gigantic explosion in which a massive star collapses and throws its outer layers into space |
| Black Hole | an object so massive and dense that even light cannot escape its gravity |
| Galaxy | large group of stars, dust, and gas held together by gravity; can be elliptical, spiral, or irregular |
| Cluster | a group of stars or galaxies bound by gravity |
| Interstellar Matter | the gas and dust located between the stars in a galaxy |
| Quasar | a very luminous, starlike object that generates energy at a high rate; quasars are thought to be the most distant objects in the universe |
| Universe | the total sum of all matter and energy that exists |
| Doppler Effect | change in the apparent frequency of a wave as observer and source move toward or away from each other |
| Big Bang Theory | (cosmology) the theory that the universe originated 20 billion years ago from the cataclysmic explosion of a small mass of matter at extremely high density and temperature |
| Troposphere | the layer closest to Earth, where almost all weather occurs; the thinnest layer |
| Stratosphere | the layer of the atmosphere that is above the troposphere and in which temperature increases as altitude increases |
| Mesosphere | the coldest layer of the atmosphere |
| Thermosphere | The uppermost layer of the atmosphere, in which temperature increases as altitude increases |
| Green House Effect | The warming of the surface and lower atmosphere of the Earth that occurs when water vapor, carbon dioxide, and gases absorb and radiate thermal energy. |
| Water Cycle | the continuous movement of water between Earth's surface and the air, changing from liquid to gas to liquid |
| Transpiration | the process by which water is lost through a plant's leaves |
| Precipitation | the falling to earth of any form of water (rain or snow or hail or sleet or mist) |
| Humidity | the amount of water vapor in the air |
| Dew Point | at constant pressure and water vapor content, the temperature at which the rate of condensation equals the rate of evaporation |
| Coriolis Effect | the curving of moving objects from a straight path due to the earth's rotation |
| Air Mass | a body of air that has about the same temperature and moisture throughout |
| Front | a boundary between two air masses |
| Climate | the average weather conditions in an area over a long period of time |
| Topgraphy | the shape of the land- its elevation,relief, and landform |
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