Unit 1
1. What are the SI units for the following?
a) Temperature:
b) Time:
c) Mass:
d) Length:
2. Which of the following numbers have zeros that are significant?
a. 2000
b. 2020
c. 3.000
d. 0.000450
3. Using pictures, describe the particulate nature of the following:
a. Liquids
b. Gases
c. Solids
4. How many protons, neutrons and electrons are found in each of the following atoms?
Protons
Neutrons
Electrons
79
-1
Br
133
Cs +1
3
H
239
Pu
56
Fe -3
23
Na+
58 2+
Ni
35 +
Cl
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Unit 1
5. Identify the elements below. How many protons, neutrons and electrons are found in each?
Element
Protons
Neutrons
Electrons
6. Match: (You can use more than one letter per match.)
Ernest Rutherford
John Dalton
J. J. Thompson
Robert Millikan
A. Oil drop experiment – mass of the electron
B. Nuclear atom
C. Atomic Theory
D. Plum pudding model of the atom.
E. Equal volumes of gas contain the same number of particles
F. Charge to mass ratio of the electron (e/m)
7. Mark the following statements as true or false.
In a neutral atom, the number of protons always equal the number of neutrons.
Electrons are less massive than neutrons.
The charge of a proton plus the charge of an electron = 0
The charge of a proton plus the charge of a neutron = +2.
Protons are much more massive than neutrons.
8. Can you write the symbol for the element with six protons in the form AZX?
Answer (yes/no)
If you answered “yes” then write it! If “no” then explain:
9. Identify the following substances as “elements”, “compounds” or “mixtures” (specify the
type of mixture – homogenous or heterogenous).
Substance
Water
Salt (NaCl)
Potassium (K)
Sweet Tea
Type
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Unit 1
Cereal and milk
Salt water
Sand and Water
Coffee mixed with creamer
Oxygen gas
10. Which of these are mixtures? (more than one)
a) Air
b) Salt water
c) Salt (NaCl)
d) Water (H2O)
11. Which of these substances are elements? (more than one)
a) Iodine
b) Silicon
c) Silicone
d) Lead
e) Water
12. Which of these mixtures are heterogeneous? (More than one)
a) Salt and water
b) Granite (rock with multicolor spots
c) Brass (alloy of copper and zinc)
d) Oil and water
13. Identify the elements that are diatomic.
14. Identify the elements that are liquids at room temperature.
15. Identify each statement below as true or false, and state why it is true or false.
a) Molecules must contain three or more atoms if they are heteroatomic.
b) Heteroatomic molecules do not maintain the properties of their constituents elements.
c) A molecule of an element can be homoatomic.
d) All pure substances are lone atoms of a single element.
e) The main difference between molecules of elements and molecules of compounds is the
number of atoms they contain.
f) A pure substance can be composed of diatomic molecules.
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Unit 1
16. What are the alternate names of the following groups?
Group 1 elements:
Group 2 elements:
Group 6 elements:
Group 7 elements:
Group 8 elements:
17. Which of the following elements would have similar properties, and why?
K, Cl, Ne, Pb, Na, Cs, Ca, Br, Kr, F, O, B
18. Determine the charge of ions of the alkali, alkaline earth, and halogen groups. Explain how
you found your answer.
19. Name/identify the following cations/anions:
Name
Chloride ion
Potassium ion
Formula
IOxide ion
Nitride ion
Aluminum ion
Li+
Ba2+
20. Calculate the mass (in grams) of 1,000. atoms of Cobalt (Co).
21. How many moles, and how many atoms are in 100. grams of Calcium?
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Unit 1
22. How many moles of N2, are in 550 grams of N2?
23. How many atoms of O, are in 25 grams of O2?
24. What do all of these carbon atoms and ions have in common?
12
C 13C 12C+ 13C-
1 dozen items = 12 items
1 mole of items = 6.022 × 1023 items
25.
a. How many elephants are there in a dozen elephants?
b. Which has more animals—a dozen elephants or a dozen chickens?
c. How many elephants are there in a mole of elephants?
d. Which has more animals—a mole of elephants or a mole of chickens?
e. Which has more atoms—a dozen H atoms or a dozen Ar atoms?
f. Which has more atoms—a mole of hydrogen atoms or a mole of argon atoms?
26. Without using a calculator:
a. Which weighs more, 18 elephants or two dozen elephants? Explain your
reasoning.
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Unit 1
b. Which weighs more, 5.136 x 1023 sodium atoms or one mole of sodium atoms?
Explain your reasoning.
27. Which has more atoms: 1.008 g of hydrogen or 39.95 g of argon? Explain your reasoning.
28. Which of the following items describe a mole?
a) The amount of the substance containing the same number of formula units as there are
atoms in 12 g of C.
b) 6.022 x 1023 items
c) Mass x acceleration
d) Avogadro’s number of items
29. Without doing the calculations, what is the mass in grams of:
a. 6.022 × 1023 hydrogen atoms?
b. 6.022 × 1023 potassium atoms?
30. What is the mass in grams of:
a. 12.044 × 1023 sodium atoms?
b. 15.0 × 1023 chlorine atoms?
31. What is the mass, in grams, of 5.000 moles of carbon atoms?
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Unit 1
32. How many magnesium atoms are there in 6.000 moles of magnesium?
33. How many bromine molecules are there in 100.0 g of bromine gas?
34. Calculate the number of atoms in each of the following:
a. 50.7 g of hydrogen gas
b. 1.00 milligram of cobalt
c. 1.00 kilogram of sulfur
d. 1.00 ton of iron
35. Describe the difference between 35Cl and 37Cl.
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Unit 1
36. Isotopic abundances are different in other parts of the universe. Suppose that on planet
Krypton we find the following stable isotopes and abundances for boron:
10
B (10.013amu) 65.75%
B (11.009amu) 25.55%
12
B (12.014amu) 8.70%
11
What is the value of the average atomic mass of boron on planet Krypton?
37. Naturally occurring chlorine is composed of 35Cl and 37Cl. The mass of 35Cl is 34.9689 amu
and the mass of 37Cl is 36.9659 amu. The average atomic mass of chlorine is 35.453 amu.
What are the percentages of 35Cl and 37Cl in naturally occurring chlorine?
38. Given the following, calculate the atomic mass of Sulfur.
Isotope
32
S
33
S
34
S
Relative mass (amu)
32.0
33.0
34.0
Natural Abundance (%)
94.99
0.75
4.25
39. What mass of iodine contains the same number of atoms as 25.0 grams of chlorine?
40. Neon has two isotopes with significant natural abundance. One of them, 20Ne, has an atomic
mass of 19.9924 amu, and its abundance is 90.5%. Show that the other isotope is 22Ne.
Explain your reasoning and include any assumptions that you make.
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Unit 1
41. Indicate whether each of the following statements is true or false and explain your reasoning.
a. On average, one Li atom weighs 6.941 grams.
b. On average, the H atom weighs 1.008 amu.
c. A certain mass of solid Na contains fewer atoms than the same mass of
gaseous Ne.
d. The average atomic mass of an unknown monatomic gas is 0.045 g/mol.
42. The entry in the periodic table for chlorine contains the symbol Cl and two numbers: 17 and
35.453. Give four pieces of information about the element chlorine which can be determined
from these numbers (two pieces for each number).
43. The atomic mass of rhenium is 186.2. Given that 37.1% of natural rhenium is rhenium-185,
what is the other stable isotope?
44. Two particles with charges q1 and q2 are separated by distance d. Rank these scenarios according
to the magnitude of the electrostatic (coulombic) potential energy. Ignore sign.
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