psci

• reactants 


  substance that exist before a chemical reaction takes place
• products


  new substances that are formed during chemical reaction
• chemical equation 


  indicate the reactants and the products of a reaction
• collision theory 


  the rate of chemical reaction is proportional to the number of collisions between the reactants principle
• chemical reactions


  happen when reactants collide with one another
• activation energy 


  the minimum amount of energy need to initiate or start a chemical reaction
• catalysts


  substance introduced in a chemical reaction that provides an alternative pathway that will utilize lower activation energy
• surface area 


  the measure of how much exposed are in a solid objects
• concentration


  there are more reactant particle in a given space of volume
• molar mass


  a compound is the mass in grams of one mole of a substance
• unit of molar mass

  g/mol
• physical law or scientific law


  a theoretical statement "inferred from particular facts, applicable to a defined groups or class of phenomena
• revolution


  movement around the sun
• rotation


  movement of the earth with its axis
• perihelion 


  moves fast when it is closer to the sun in january
• aphelion 


  moves slowest when it is farthest away the sun in early July
• diurnal motion 


  the daily motion of stars and other celestial bodies across the sky
• annual motion


  referred to the events or phenomena that came annually or yearly
• precession


  a change in the orientation of the rotational axis of rotating body
• shape of earth


  oblate spheroid
• solstices


  the two day where the sun is at the Zenith 23.5 degree north of south of the equator
• winter solstice


  occurs on Dec. 21 and marks beginning of winter (shortest day of the year)
• summer solstice


  occurs on June 21 and marks the beginning of summer (longest day of the year)
• equinox


  equal day and night
• pythagoras


  first proposed the spherical earth
• anaxagoras


  observes that during a lunar eclipse, the earth's shadow was reflected on the moon
• aristotle


  he listed several arguments for a spherical earth
• eratosthenes 


  made the first successful attempt to determine the size of the earth
• aristarchus


  first greek to profess heliocentric view
• hipparchus


  observed and compared the brightness of 850 stars and arrange them into order of brightness or magnitude
• claudius ptlolemy


  he believed that the earth was the center of the universe
• new moon 


  appears only when the moon is on the side of the earth most
• first quarter


  half side of the moon facing the earth appears illuminated
• gibbous


  figure of the moon that is more than half full, looking swollen on the side
• crescent


  figure of the moon that appears as a curve with pointy ends
• waxing


  growing; describes the moon when the illuminated portion is increasing
• waning


  shrinking; describes the moon when the illuminated portion is decreasing
• full moon 


  the whole side of the moon is now illuminated to viewers from the earth
• sme


  solar eclipse
• sem


  lunar eclipse