Chemistry 100 –Chemistry Today
Exam 2 (May 3, 2002)
Questions 1 - 6 (24 points) are multiple choice questions. There will be no partial credit given for these problems. Problems 7 - 20 (76 points) are short response questions and should be worked out on the exam for partial credit to be given. In these last sets of problems, the answer by itself may not be satisfactory for full credit.
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There is a blank page at the end of this examination for use as scratch paper.
Periodic Table
Name:
1. (4) Which of the following of Dalton’s proposals proved to be incorrect?
a. Atoms of different elements can combine to form compounds.
b. Atoms of the same element are identical.
c. Atoms can combine in small whole numbers.
d. Atoms can combine in more than one whole number ratio.
e. none of the above.
2. (4) Which of the following subatomic particles can be found inside the nucleus?
a. electrons
b. neutrons
c. protons
d. Neutrons and protons
e. none of the above
3. (4) Which of the following instruments gives a quantized measurement?
a. 10 mL graduated cylinder
b. meter stick
c. 250 mL beaker
d. 10 cc syringe
e. 500 g digital balance
4. (4) Why did Mendeleev not include germanium in his periodic table of 1871?
a. Ge is unstable
b. Ge is a semimetal
c. Ge had not been discovered
d. Ge is only found in compounds
e. none of the above
5. (4) Which of the following has the smallest atomic radius?
a. C
b. N
c. O
d. P
e. S
6. (4) Which of the following is evidence for a chemical reaction?
- Change in physical state
- Change in odor
- Change in solubility
- Change in color
- None of the above
7. (4) According to Dalton, if hydrogen is represented by the symbol , and oxygen is represented by the symbol ¡, show a balanced representation of hydrogen gas reacting with oxygen gas to form water.
8. (6) In Rutherford’s gold foil experiment, he shot a particles (a helium nucleus) at a very thin slice of gold. He found that
1. Most particles went through the foil.
2. Some particles were deflected slightly.
3. A small number of particles bounced back – The most shocking surprise!
Tell me what each of these observations told Rutherford about the atomic structure.
9. (4) Fill in the missing information (x and y)
a.
b.
c. where this isotope of mercury has a mass of 205
d. where this atom has 1 neutron
10. (8) List the colors of visible light in order from shortest wavelength to longest wavelength. Which of these colors has the highest frequency and which has the smallest frequency?
11. (6) List the following types of electromagnetic radiation in order of most damaging to molecules (and thus to people) to least damaging: visible, gamma, ultraviolet, radio, infrared, microwave.
12. (4) Predict the density of calcium, given the density of strontium (2.54 g/cm3) and barium (3.5 g/cm3)
13. (4) Outline on the periodic table below where the s, p, d, and f blocks are:
14. (2) How many valence electrons does carbon have? Draw a Lewis dot structure for it.
15. (5) Write electronic configurations for the following (you may use a noble gas core):
a) N
b) Ni
c) S2-
d) Sn2+
e) Mn2+
16. (7) Give the missing ion formula or name of the ion.
a) NO3-
b) Ammonium
c) SO42-
d) Phosphate
e) Carbonate
f) HCO3-
g) Hydroxide
17. (7) Write formulas or names for the following:
a) molybdenum(III) hydroxide
b) dinitrogen tetroxide
c) Mg(NO3)2
d) ammonium sulfide
e) HNO3
f) phosphoric acid
g) HI (aq)
18. (4) Give the product formula and the name of the product for the following reactions (you will need to balance them too):
a) Ca2+ + Cl- à
b) Al3+ + SO42- à
c) Cobalt(II) ion and phosphide ion à
19. (5) In lab you found that (at least in one case!) potassium can be explosive when put into water. Tell me what you know (and how you know this) about the ionization energy of potassium in comparison to the other metals you reacted with water (lithium, sodium, magnesium, and calcium).
20. (10) Write out the full equations and balance them. Finally, categorize them as either a combination, decomposition, single replacement, double replacement, or neutralization reactions:
CATEGORY
a) P4 + O2 à P2O5
b) Aluminum metal reacts with manganese(II) oxide to form aluminum oxide and manganese metal
c) H3PO4 + Ba(OH)2 à
d) Zn(HCO3) ZnCO3 + CO2 + H2O
e) Silver(I) nitrate reacts with potassium chloride to form silver(I) chloride and potassium nitrate
Extra Credit (8): Tell me what the different types of radiation listed in Q#11 do to molecules.