## Assignment—Atoms, Molecules, and Ions

As you work these matter and measurement problems, consider and explain:

A. What type of question is it?

B. How do you know what type of question it is?

C. What information are you looking for?

D. What information do they give?

E. How will you go about solving this?

F. Show how to solve the problem.

G. Be able to answer for a different reaction, number, set of conditions, etc.

## Sample Questions

1. Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?
A) NH4 and NH4Cl
B) ZnO2 and ZnCl2
C) H2O and HCl
D) NO and NO2
E) CH4 and CO2
2. A sample of chemical X is found to contain 5.0 grams of oxygen, 10.0 grams of carbon, and 20.0
grams of nitrogen. The law of definite proportion would predict that a 70 gram sample of chemical
X should contain how many grams of carbon?
3. How many of the following postulates of Dalton’s atomic theory are still scientifically accepted?
I. All atoms of the same element are identical.
II. Compounds are combinations of different atoms.
III. A chemical reaction changes the way atoms are grouped together.
IV. Atoms are indestructible.
4. Who was the first scientist to show that atoms emit any negative particles?
5. Many classic experiments have given us indirect evidence of the nature of the atom. Which of the experiments listed below did not give the results described?
A) The Rutherford experiment proved the Thomson “plum-pudding” model of the atom to be essentially correct.
B) The Rutherford experiment was useful in determining the nuclear charge on the atom.
C) Millikan’s oil-drop experiment showed that the charge on any particle was a simple multiple of the charge on the electron.
D) The electric discharge tube proved that electrons have a negative charge.
E) All of the above experiments gave the results described.
6. Which one of the following statements about atomic structure is false?
A) An atom is mostly empty space.
B) Almost all of the mass of the atom is concentrated in the nucleus.
C) The protons and neutrons in the nucleus are very tightly packed.
D) The number of protons and neutrons is always the same in the neutral atom.
E) All of the above statements (A-D) are true.
7. Which of the following atomic symbols is incorrect?
A) ${}_{14}^{16}\text{C}$
B) ${}_{17}^{37}\text{Cl}$
C) ${}_{15}^{32}\text{P}$
D) ${}_{19}^{39}\text{K}$
E) ${}_{14}^{8}\text{N}$
8. The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. What does Rhenium-185 have in its nucleus?
9. Which among the following represents a set of isotopes? Atomic nuclei containing:
I. 20 protons and 20 neutrons
II. 21 protons and 19 neutrons
III. 22 neutrons and 18 protons
IV. 20 protons and 22 neutrons
V. 21 protons and 20 neutrons
10. How many protons, neutrons, and electrons does ${}_{20}^{40}\text{Ca}^{2+}$ have?
11. Which of the following is a species with 12 protons and 10 electrons?
A) Ne2+
B) Ti2+
C) Mg2+
D) Mg
E) Ne2-
12. How many protons, neutrons, and electrons are in ${}_{19}^{39}\text{K+}$
13. What does the formula of water, H2O, suggest?
A) There is twice as much mass of hydrogen as oxygen in each molecule.
B) There are two hydrogen atoms and one oxygen atom per water molecule.
C) There is twice as much mass of oxygen as hydrogen in each molecule.
D) There are two oxygen atoms and one hydrogen atom per water molecule.
E) None of these.
14. Which of the following are incorrectly paired?
A) K, alkali metal
B) Ba, alkaline earth metal
C) O, halogen
D) Ne, noble gas
E) Ni, transition metal
15. Which of the following are incorrectly paired?
A) Copper, Cu
B) Carbon, C
C) Cobalt, Co
D) Calcium, Ca
E) Cesium, Ce
16. All of the following are characteristics of metals except:
A) good conductors of heat
B) malleable
C) ductile
D) often lustrous
E) tend to gain electrons in chemical reactions
17. Which of the following names is incorrect?
A) cobalt(II) chloride
B) magnesium oxide
C) aluminum(III) oxide
D) diphosphorus pentoxide
E) All of the above names are correct
18. Which of the following pairs is incorrect?
A) iodine trichloride, ICl3
B) phosophorus pentoxide, P2O5
C) ammonia, NH3
D) sulfur hexafluoride, SF6
E) All of the above pairs are correct.
19. How many oxygen atoms are there in one formula unit of Ca2+?
20. What is the correct name for FeO?
21. What is the correct name for Ca2+?
22. What is the correct name for V3+?
23. What is the subscript of barium in the formula of barium sulfate?
24. What is the formula for calcium bisulfate?
25. Which of the following is incorrectly named?
B) NH4ClO4, ammonium perchlorate
C) PO43-, phosphate ion
D) Mg(OH)2, magnesium hydroxide
E) NO3-, nitrite ion

1. D
2. 20 grams
3. 2
4. J. J. Thomson
5. A
6. D
7. E
8. 75 protons, 110 neutrons
9. I, IV and II, V
10. 20 protons, 20 neutrons, and 18 electrons
11. C
12. 19 p, 20 n, 18 e
13. B
14. C
15. E
16. E
17. C
18. B
19. 8
20. iron(II) oxide
21. calcium ion