Chapter 3 Homework
Atoms: The Building Blocks of Matter – 5 points
Read Pages 65-82 and answer the following questions: (Remember that “Think about it” questions are not necessarily answered in the text and they are often good indicators of general quiz questions)
1. Around what year and which philosopher first supported a particle theory of matter?
2. What famous philosopher did not believe in atoms. (but his view became accepted for 2000 yrs)
3. True or False: When elements combine to make a compound they always do so in the same ratio.
4. What is the law of conservation of mass?
5. NaCl is table salt. What percent is Na and what percent is Cl by mass?
6. What is the law of definite proportions? (see how it relates to question #5)
7. True or False: An element can have atoms with different masses.
8. What are the two regions of atoms and what are contained in these regions?
9. What are the charges on the three subatomic particles which make up atoms?
10. What is the charge of an anode electrode? What is the charge of a cathode electrode?
11. How did scientists illustrate that cathode rays had mass?
12. How did scientists illustrate that cathode rays were negatively charged?
13. What subatomic particle did Joseph Thompson discover in cathode rays?
14. What did Robert Millikan discover to be the mass of an electron? (in kg)
15. Did it matter which metal they used for electrodes or gas in the tube? Why would this be important?
16. What two other inferences could scientists now make about the composition of an atom.
17. What did Rutherford, Geiger and Marsden bombard with positive alpha particles in 1911?
18. After two years of thinking, what explanation did Rutherford have for the results? (fig. 3-7)
19. True or False: The nucleus of an atom makes up the majority of an atom’s volume.
20. If the nucleus of an atom were the size of a marble, how big would the entire atom be?
21. True or False: Atoms contain the exact same number of protons as electrons.
22. What is the mass of a proton? How many times greater than the mass of an electron?
23. What is the mass of a neutron? Which subatomic particle is it closest to in mass?
24. The number of __________ in a nucleus determines that atom’s identity.
25. What percent of air is Ne and how many Ne particles are in each breath you take?
26. What does the atomic number tell you about an atom?
27. Think about it: What other subatomic particle can be determined by the atomic number?
28. What’s an isotope and what makes it an isotope?
29. What does the mass number tell you about an atom?
30. What is the formula for finding the # of neutrons from the mass # and the atomic #? (look at the practice problems on p. 77-78, those will be on the quiz)
31. How much does one single solitary atom of oxygen-16 weigh?
32. What is the standard atom used to determine one atomic mass unit?
33. What is the average atomic mass?
34. Find the weighted average of 100 balls with a mass of 5.00 g each and 2 balls with a mass of 10.0 g each (be sure to round to three significant digits)
35. How many numbers after the decimal place should you round atomic masses?
36. What is a mole?
37. True or False: A mole is a weight
38. What is the numerical value of the mole (also known as Avogadro’s number)
39. What is molar mass?
40. What are the units for molar mass?
1 mole = 6.02 x 1023 atoms (or molecules or formula units)
AND Grams ß----à Moles ß---à Molecules (or Formula units or atoms)
1. 3 moles of Magnesium has what mass?
2. 8 moles of Sodium has what mass?
3. 5 moles of Calcium has what mass?
4. How many moles are in 20.6 g of Magnesium?
5. How many moles are in 45.7 g of Sodium?
6. How many moles are in 89.6 g of Calcium?
7. If you have 5.67 x 1028 atoms of Magnesium, how many moles is this?
8. If you have 3.25 x 1029 atoms of Sodium, how many moles is this?
9. If you have 7.52 x 1031 atoms of Calcium, how many moles is this?
10. If you have 2.23 x 1028 molecules of water, how many moles is this?
11. If you have 9.63 x 1022 formula units of sodium chloride, how many moles is this?
12. If you have 5.67 x 1032 formula units of Magnesium Hydroxide, how many moles?
13. If you have 4.00 moles of Magnesium, how many atoms is this?
14. If you have 5.90 moles of Sodium, how many atoms is this?
15. If you have 7.00 moles of Calcium, how many atoms is this?
16. If you have 4.50 g of Magnesium, how many atoms is this?
17. If you have 6.70 g of Sodium, how many atoms is this?
18. If you have 5.60 g of water, how many molecules is this?
19. If you have 9.00 g of Magnesium hydroxide, how many formula units is this?
20. If you have 5.67 x 1028 atoms of Magnesium, how many grams is this?
21. If you have 3.25 x 1029 atoms of Sodium, how many grams is this?
22. If you have 7.52 x 1031 atoms of Calcium, how many grams is this?
23. If you have 2.23 x 1028 molecules of water, how many grams is this?
24. If you have 9.63 x 1022 formula units of sodium chloride, how many grams is this?
25. If you have 5.67 x 1032 formula units of Magnesium Hydroxide, how many grams?
Also, from the book, do the following: (The answers are in the book – And, there are sample problems before each of these.)
p. 222 Practice problem #1
p. 223 Practice problems #1-2
p. 226 Practice problems #1-2
Answers to chapter 3 homework.
Converting grams to moles to molecules
9. 1.25 x 108mol
10. 3.70 x 104mol
12. 9.42 x 108 mol
13. 2.41 x 1024 atoms
14. 3.55 x 1024 atoms
15. 4.21 x 1024 atoms
16. 1.11 x 1023 atoms
17. 1.75 x1023 atoms
18. 1.87 x 1023 mol
19. 9.29 x 1022 form. Units
20. 2.29 x 106 g
21. 1.24 x 107 g
22. 5.01 x 109 g
23. 6.67 x 105 g
25. 5.49 x 1010 g