CHE 17 Name

Test 1

March 14, 1997

Multiple choice: (2 points each)

  1. A pure substance which can be decomposed into two or more pure substances is a(n)
    1. element.
    2. mixture.
    3. compound.
    4. atom.
  1. In a neutral atom there is an equal number of
    1. protons and electrons
    2. neutrons and protons
    3. electrons and neutrons
    4. protons, neutrons, and electrons
  1. A model which explains why matter behaves as it does is known as
    1. a scientific law.
    2. a hypothesis.
    3. a conclusion.
    4. a theory.

4. Mendeleev put Te (atomic weight 128) before I (atomic weight 127) because

(a) Atomic weights were placed in descending order to accomplish periodicity among the elements.

(b) Te has a lower atomic number, a concept established by the time of Mendeleev.

(c) The trend was to put nonmetals before metals in a given period of the periodic table.

(d) This arrangement put both elements into proper groups, all elements in a group having similar properties.

5. According to Bohr's theory of the atom,

(a) electrons are in fixed orbits.

(b) electrons spend most of the time in the nucleus.

(c) electrons do not undergo transitions from one energy level to another.

(d) electrons in atoms can be located by a mathematical function, which expresses the probability of finding them in a given volume around the nucleus.

Short answer:

6. Is it possible to have a mixture of two elements and also to have a compound of the same two elements? Explain. (7 points)

 

 

 

7. When light is emitted by an atom, what change has occurred within the atom? (7 points)

 

 

 

 

 

8. What subatomic particles are in an atom of Iron (Fe)? How many particles of each type are present in an atom of 52Fe? (6 points)

 

 

 

 

  1. Which of the following isotopes are the same element? Explain briefly. (5 points)

 

A

B

C

D

atomic number

16

15

14

15

mass number

32

32

32

31

 

 

 

 

 

Problems:

10. Balance the following chemical equations. (4 points each)

 

Al + Cl2 AlCl3

 

  1. Balance the following nuclear equations. (4 points each)

 

 

12. Bananas are selling for $1.00 per kg. What is the price per ounce? Show your work for full credit! (Useful information: 453.6 g = 1 pound; 16 ounces = 1 pound) (8 points)

 

 

 

 

 

 

13. Write the electron configuration for Vanadium (V). (5 points)

 

 

 

 

 

 

 

14. Draw an energy level diagram that shows how the electrons fill the atomic orbitals in phosphorous (P). (5 points)

 

 

 

 

 

 

 

  1. Phosphorus-32 decays by beta emission and has a half life of 14 days. How much activity will remain in a 100 mCi sample after 10 weeks? Show your work for full credit! (7 points)

 

 

 

 

 

 

 

 

 

 

Essays: Write your answers in complete sentences, using proper grammar. (12 points each)

16. Our theory of atoms has changed significantly since Dalton proposed his atomic theory. Describe the experimental discoveries which conflicted with Daltonís theory and how the theory has changed to be more consistent with the known observations.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Describe one of the useful applications of radioactivity, including the risks and benefits of this use of technology.