DAT General Chemistry Exam Solution.

Atomic Number - correct answer number of protons found in that atom; low number; (Z) Mass Number - correct answer Protons + Neutrons; high number; (A) Atomic Mass - correct answer relative mass of that atom compared to the mass of a carbon-12 atom (which is set at 12.00); measured in amu; 1 amu = - correct answer 1.66x10^-24 Atomic Weight - correct answer weight (g) of one mole (mol) of a given element (g/mol); the weighted average of all the masses (not the weights) of an element, weighted according to the natural abundance of the isotopic species of an element 1mol = ______ (Avagadro's Number) - correct answer 6.022x10^23 molecules Isotope - correct answer multiple species of an atom with same number of protons and a different number of neutrons (different mass numbers); generally exhibit same chemical properties Ernest Rutherford - correct answer 1911; gave experimental evidence that an atom has a dense, positively charged nucleus that accounts for a small portion of the volume of the atom Max Planck - correct answer developed first quantum theory; 1900; proposed that energy emitted as electromagnetic radiation from matter comes in discrete bundles called quanta; E=hv (h-Planck's constant) Planck's constant - correct answer 6.626x10^-34 J*s The Bohr Model of the Atom - correct answer developed 1913 model of H atom using Rutherford and Planck's findings; H atom has central proton, electron travels around it in a circular orbit; centripetal force acting on the electron as it revolved around the nucleus was the electrical force between the positively charged proton and negatively charged electron; quantized angular momentum so it changed in discrete amounts in relation to the quantum number (L=nh/2pi) n=quantum number h=Planck's constant; from this Energy of an electron: E=-Rh/n^2, Rh=Rydberg constant 2.18*10^-18 J/electron Rydberg Constant - correct answer 2.18 x 10^-18 J/electron Smaller orbit of electron the... - correct answer lower the energy state What is the Bohr Model used for? - correct answer used to explain the atomic emission spectrum and atomic absorption spectrum of hydrogen; because these spectrum are not the continuous spectrum that classical physics would expect, they are line spectrum