CEM 141 MSU Exam 1 Questions and Answers Already Passed

CEM 141 MSU Exam 1 Questions and Answers Already Passed The statement "If I add cold milk to hot coffee the temperature will decrease," is a? Claim, always include an explanation and reasoning to the claim. Scientific Model Models are used to make testable predictions How much is a picometer? 0.1 x 10^-12 meters Atomic Force Microscopy/ Scanning Tunneling Microscopy Microscopes that now allows us to view atoms. Leaves are green in the summer because? A plant's leaves are green in the summer because they contain chlorophyll. Chlorophyll is a natural pigment that absorbs all wavelengths in the visible spectrum except green. How many naturally occurring elements exist? 91 What was Dalton's Atomic theory? (1808) - Elements are composed of small particles called Atoms. - Atoms of a given element are different from atoms of other elements. -Chemical reactions happen when atoms are rearranged. - Compounds contain 2 or more elements. What was J.J. Thomson's experiment, and what did he discover? Using a Cathode Ray Tube, he noticed that particles emerged to the cathode disk, and moved to another, the anode. These particles could be deflected by electrical fields that would indicate that they would be negatively charged. They were also deflected by magnetic fields, which showed the particles carried the charge as the ray was bent. The most important observation was that the type of cathode used did not matter, as these particles were still emitted. Therefore, Thomson deduced that the particles were universal and were in fact negatively charged components of the atom. (The Electron) What was Ernest Rutherford's experiment, what did he discover? Ernest Rutherford fired Alpha particles (Hydrogen atoms) at a thin sheet of gold foil. Had Thomson's theory been right about the plum pudding model, then the atoms should have all passed right through the sheet with no exceptions. However, a small ratio of these particles were deflected. With this information, Rutherford figured there was a small dense nucleus in the atom and that most of the atom was empty space. What is the difference between Law and Theory? A law describes - tells you what happens A theory explains - tells you why it happens How big is an atom (H)? About 0.1 nanometer (0.1 x 10-9m) Which is biggest? Atom, Molecule, Cell, or it depends?