Unit II: Atomic Structure and Nuclear Chemistry Review Sheet

1. Describe the various models in the historical development of modern atomic theory:

a. Aristotle: Matter is made of Air, Fire, Earth, & Water. b. Democritus: The first to say that matter is composed of

atom, or “atomos.” c. Dalton: Had five basic principles in his model of the atom d. Thomson: discovered the charge of the electron with his

Cathode Ray Tube, and theorized that the atom was a “plum pudding” of electrons and positive charges.

e. Rutherford: Used the Gold Foil experiment to prove the Plum Pudding Model, only to discover that the atom has a nucleus, filled with protons, and other significant mass. The atom is mainly empty space, where the mass of the atom lies within the nucleus.

f. Bohr: Electrons move about the nucleus in “orbits” in Quantum Energy levels. The maximum number of electrons per energy level is 2n2, where n = the energy level number.

g. Quantum Mechanical Model: electrons spin around the nucleus in clouds of probabilities.

2. Distinguish among

protons, neutrons, and electrons in terms of their relative masses, charges, and location with respect to the nucleus

3. Infer the number of protons, neutrons, and electrons using the atomic number and

mass number of an element from the periodic table and symbol notation i.e. 9

19F has 9 protons, 9 electrons (both determined by the Atomic Number), and 10 neutrons (Mass Number – Atomic Number)

4. Explain how isotopes of an element differ:

Atoms of the same element with different Mass Numbers, and thus, different numbers of neutrons.

5. What are the three isotopes of Hydrogen?

6. Explain why the atomic masses of elements are not whole numbers: Atomic Masses are “Weighted Averages” of the naturally occurring isotopes.

GHS Honors ChemGHS Honors Chem

Hydrogen IsotopesHydrogen IsotopesHydrogen has _____ isotopesHydrogen has _____ isotopes

1111HH

2211HH

3311HH

1 proton and 2 1 proton and 2 neutrons, neutrons, tritiumtritium

radioactiveradioactive

1 proton and 1 1 proton and 1 neutron, neutron, deuteriumdeuterium

1 proton and 0 1 proton and 0 neutrons, neutrons, protiumprotium

7. Calculate the average atomic mass of an element from isotope data

8. Differentiate between an atom and an ion

9. Determine ion charge given proton, neutron, and electron data

10. The Periodic Table: What is the Periodic Law? The Periodic Law states that when the elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties.

a. The horizontal rows are called the periods. There are seven periods. Elements within the same period have the same number of energy levels at least partially filled.

b. The vertical columns are called groups or families. Elements within the same group have similar properties.

11. What are the properties of metals and nonmetals? Where are the metalloids? Where

are the Transition Metals? The Lanthanides? The Actinides? 12. What is the significance of the A Groups? What are the group names, and what are the

expected charges for the A Groups elements?

13. Distinguish between isotopes and radioisotopes in terms of stability and radioactive decays

14. Contrast the characteristics of alpha, beta, and gamma radiation emitted during radioactive decay

15. Use symbol notation for subatomic

particles and particle radiation

16. Write balanced nuclear equations for alpha decay and beta decay processes, positron emission, electron capture, or positron capture.

17. Compute the amount of radioisotope remaining at a given time using the half-life method. What are the isotopes used for dating? U-238 decays to Pb-206, which is used to date the Earth. C-14 is produced in the upper atmosphere, and enters the ecosystem. C-14 is used to date living organisms.

18. What makes a Nuclei Unstable? Elements above an Atomic Number of 83 are all

radioactive. The ratio of Neutrons to Protons are too high.

19. Write equations to show how transuranium elements are synthesized by transmutation

20. Distinguish between artificial and natural

transmutation

21. Write balanced nuclear equations for artificial transmutation

i.e. 94Be + 42He � 126C + ___

22. Compare and contrast nuclear fusion and

nuclear fission

For Fission, a Critical Mass is needed to Start and maintain a Chain Reaction. The only fuels for Fission are Uranium-235 and Plutonium-239.

GHS Honors ChemGHS Honors Chem

TransuraniumTransuranium ElementsElements

Elements beyond 92 Elements beyond 92 ((transuraniumtransuranium)) made made

starting with an starting with an reactionreaction

2382389292U + U + 11

00n n ------> > 2392399292U + U +

2392399292U U ------> > 239239

9393Np + Np + 00--11

2392399393Np Np ------> > 239239

9494Pu + Pu + 00--11

Fusion is the combination of small nuclei, and occurs in the Sun and other stars. Fusion is not practical as a source of energy since it occurs at EXTREMELY high temperatures.

GHS Honors ChemGHS Honors Chem

Nuclear FusionNuclear Fusion

Fusion Fusion small nuclei combinesmall nuclei combine

22H + H + 33H H 44He + He + 11n +n +1 1 2 1 1 2 00

Occurs in the sun and other starsOccurs in the sun and other stars

Energy

23. Calculate the energy released during a nuclear reaction using the Mass defect, and the

relationship between that Mass Defect, and the Binding Energy in E = mc2. 24. Compare simple nuclear fission with the controlled fission reactions that are used to

generate energy in a nuclear reactor.

Originally discovered by Enrico Fermi, the fission fuel of a nuclear reactor is arranged as a “Fission Pile” so that the reaction is slow and continuous. This is a departure from the critical mass of an atomic bomb, which produces an uncontrollable fission reaction. In the reactor chamber, Boron or Cadmium Control Rods are used to stop the flow of the neutrons, or stop the reaction. In the older reactor such as Chernobyl, graphite walls are used as a moderator to slow the

speed of the neutrons. In those older reactors, water is used to cool the reactor and transfer heat to spin a turbine. If this water leaks out, the reaction will increase uncontrollably. In the newer reactors like those here in the states, water is used as a moderator to slow neutrons so that they will strike the Uranium fuel, and to transfer heat to the water used to spin the turbine. Should that water leak out, the reactor will slow to a stop, since water is the only moderator.

25. Is nuclear energy a viable alternative to fossil fuel energy? What are the real and imagined dangers of a nuclear reactor? What were the technical & human elements of those accidents that occurred at Three Mile Island & Chernobyl? What were the major technological differences between the two power plants?

26. What is the future of nuclear power as an alternative fuel source?