CEM 141 Final Exam Questions and Answers Already Passed

CEM 141 Final Exam Questions and Answers Already Passed Why are alpha particles deflected by the nucleus? Because both the alpha particles and the nucleus are positively charged and so the alpha particle is repelled. Is this statement (Dalton's Theory) true or false and why? "All atoms of an element are identical and have the same mass and properties." False. Atoms of the same element can have different numbers of neutrons. What is the evidence that electrons are subatomic particles? The nature of the electron is independent of the material from which it emerges. Example of a theory (explains) The properties of matter can be EXPLAINED by understanding that matter is composed of atoms that interact and move in various predictable ways. Why is the boiling point of iodine higher than that of bromine? Because iodine has a larger more polarizable electron cloud. The electrostatic attraction between the iodine molecules requires more energy to overcome. When bromine melts, what is happening? Attractive forces between molecules are overcome. When oxygen freezes, what is happening with the forces and energy changes during this process? New LDFs are formed. Energy is released to the surroundings. Energy is transferred via collisions. Where would two atoms of He be most stable on a PE curve? The PE well, where the attractive and repulsive forces are equal and the system is most stable. For a pencil sitting on a desk, what forces are acting upon the pencil? Both gravitational and electrostatic. If the PE increases as two particles approach, what are they most likely? Two protons (positively charged/same charge). How do atoms know that temperature is increasing? Thermal energy is transferred upon collision with other atoms. What two atoms would have the greatest gravitational forces? Two 10g separated by 10 meters. Or, one 100g and one 1g separated by 5 meters? m1m2/r^2 100g and 1g separated by 5 meters. (100)(1)/(25) = 4 In the solid state, atoms of xenon are held together by.. London Dispersion Forces ONLY because Xenon is a noble gas that cannot bond together. What does a lower PE well mean? What does a further right position on the PE graph mean? More energy needed to break interactions. Longer bond. What is true about the PE minimum for the approach of two atoms? The depth of the well tells you how much energy is required to