Chemistry Mid-term Exam

Directions: It is important that you provide answers in your own words. Please focus only on information from the text/eBook to create your own solutions. Please do not use direct information from an outside source (especially copying and pasting from an "answer" website). Use of direct information from an outside source is against school policy. All answers will be checked for plagiarism. Instances of plagiarism can result in probation or possible dismissal from the school.

Please be sure to follow all guidelines (number of sentences/showing all calculations) and to provide the correct metric units of measure. All questions are 5 points (1 point for sentence number /units).

1. Experimental Design: From the work you have done this semester, choose a topic and design an experiment you would be able to perform. In your design (1) state your hypothesis, (2) identify your dependent and (3) independent variables, (4) your control conditions and (5) describe your experimental procedure.

2. Perform this operation and report the answer to the correct number of significant figures: What is the mass of a cube of aluminum that is 4.0 cm on each edge? The density of aluminum is 2.7 g/cm³. Show all calculations leading to an answer.

3. Explain why a model of the atom is crucial to understanding chemistry and in explaining the behavior of matter. Use 3 - 4 sentences in your explanation.

4. What parts of Dalton's atomic theory no longer agree with the current picture of the atom? Provide an answer using 3 - 4 sentences in your own words.

5. If an element has 12 protons and 17 neutrons, how many electrons must it have?

6. Why are the atomic masses of elements usually decimal numbers? Provide an answer using 3 - 4 sentences in your own words.

7. In 3 - 4 sentences and in your own words describe how Mendeleev's periodic table differs from Moseley's.

8. What is the electron configuration of the element with 27 protons?

9. How many electrons are in the highest energy orbital of the element copper?

10. How many dots should be indicated in the electron dot structure of arsenic?

11. Why is the first ionization energy of a nonmetal much higher than that of an alkali metal in its same period? Provide an answer using 3 - 4 sentences in your own words.

12. Why do compounds with strong intermolecular attractive forces have higher boiling points than compounds with weak intermolecular attractive forces? Provide an answer using 3 - 4 sentences and in your own words.

13. Write the formula for iron (III) sulfate.

14. What is the reason the group 13 metals have a typical charge of 3+?

15. Why does one mole of carbon atoms have a smaller mass than one mole of sulfur atoms?

16. What is the percentage of nitrogen in N₂O? Show all calculations leading to an answer.

17. How many non-bonding electrons does phosphorus have?

18. Complete and balance this reaction: sulfuric acid reacts with barium chloride

19. Identify the precipitate in this reaction: calcium nitrate reacts with sodium phosphate.

20. The following is a Limiting Reactant problem:

Magnesium nitride is formed in the reaction of magnesium metal with nitrogen gas in this reaction: 3 Mg_(s) + N_2(g)à Mg₃N_2(s)

How many grams of product are formed from 2.0 mol of N_{2 (g)} and 8.0 mol of Mg_(s)? Show all calculations leading to an answer.