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Which of the following molecules have a net dipole moment?  Choose all that apply.

Complete the following passage with the best answers.  Some answers may be used more than once, some may not be used. Acids and bases can be strong or weak, and in their stronger forms can be highly 1)__________________, capable of causing chemical burns and degradation to many kinds of materials, including metals and biological tissues.  However, acids and bases can neutralize eachother, and generally form harmless, inert products like water and 2)_________________.  The behavior of acids and bases depends on the concentration and 3)__________________ of the acidic or basic species.  Historically, there have been a number of ways that acids and bases have been defined.  The 4)_________________ definition states that acids produce H+ in solution, bases produce OH- in solution.  These sorts of acids and bases are 5)__________________, in that they dissociate in solution to form ions (H+ and OH-).  In most such acids, the ionizing hydrogen is bonded to a highly 6)________________ atom such as Cl, Br, F, or O, which dissociates to form H+ and an anion.  In aqueous solution, H+ is stabilized by complexes with water such as H3O+ — also known as the 7)______________ ion — and others.  H+ is often referred to simply as a proton; gain of H+ is known as 8)____________________, loss of H+ as 9)__________________.  Bases similarly dissolve to form OH-; metal hydroxides are very common and form OH- and M+ upon dissociation.  By the latter 10)__________________________ definition, acids donate H+, and bases accept H+.  By this definition, ammonia exhibits basic behavior by accepting H+; it is also sort-of a base by the earlier definition, because it reacts with water to form OH-.

The three primary phases of ordinary matter are solids, liquids and gasses. 1)_____________________ are characterized by having their atoms located in fixed positions; in the 2)_______________________ phase, particles experience significant attraction to one another and are located close together, but not in fixed positions such that they can slide past one another; in the 3)__________________ phase, particles do not experience enough attraction to one another to stay together, and move independently with little interaction. Transitions between phases of matter are often possible with changes in 4)_________________. As heat energy is added, particle movement increases, and as attractive forces are overcome, solids can transition to liquids and liquids to gasses. The stronger the attractive interactions are, the more energy is required, resulting in higher 5)____________________________ points.

Which pairs of elements show the proper order of electronegativity, with the most electronegative atoms or elements further to the left?  Choose all that apply.

Complete the following passage with the best answers.  Some answers may be used more than once, some answers may not be used. Bond 1)___________________ is an uneven distribution of electronic charge along a covalent bond, which results from electrons being unevenly shared as a result of differences in attraction to each atom of the bond.  This difference in attraction is the result of differences in 2)______________________, an idea proposed by Linus Pauling, which says that even formally charge-neutral atoms may attract electrons more strongly than others as a result of differences in atomic size and the the atom’s valence shell energy level.  In this way, such bonds may be ‘in-between’ the more idealized fully ionic and covalent sorts of bonds.  The polarization of such bonds can be expressed with either 3)________________ notation, which is a way of expressing a partial positive or negative charge on the bonded atoms, or 4)_________________ notation, which ‘points’ from the more-positive to the more-negative of the atoms in the bond.  The presence of such bonds may or may not render a molecule overall to show a similar charge-imbalance, known as a 5)__________________, depending on the geometry of the molecule and the way that individual bond polarizations add together.

40 questions, multiple choice and free response.  2 hours allowed. Be sure to have a calculator, periodic table, formula sheet, and scratch paper and pencil available before starting the test.  Good luck! Unless specifically asked, do not enter units for calculated answers as part of the answer.  You will be prompted for the units that your *numerical answer* should be expressed in. In the event you need to use scientific notation to answer a question, use exponential notation, i.e., c = speed of light = 3.00 x 10^8 m/s = 3.00e8.  Planck’s constant = 6.626e-34 J/s.  However, most questions should be structured such that you can just use standard numerical expressions.

Match each molecular formula with the correct molecular geometry.  Some answers may be used more than once, some may not be used.

An operator loses his job at the refinery and decides to supplement his income by free-basing cocaine with drain cleaner and selling at a mark-up while he looks for another job (no, I am not advocating anything like this, just thought it would make for a fun and interesting exam question).  He is able to procure [m] grams of cocaine as the hydrochloride powder (molecular weight = 339.6 g/mol) and finds that [vbase] mL of drain cleaner (NaOH) from the hardware store can be titrated with [vacid] mL of [Macid] M muriatic acid (HCl) from the pool supply center.  What volume of drain cleaner should he use to convert his powder cocaine into crack?  Report your answer in mL.  As usual, no units needed, just report the number of mL. cocaine_crack.png 

Calculate the number of atoms in [x] grams of magnesium.  You will probably need to use exponential format on this one — your answer should look something like 1.23e56, where the e takes the place of “x 10^” in scientific notation.

The outer shell of an atom is known as its 1) ________________ shell.