Chemistry Midterm Study Guide
Unit 1 – What Can We Measure About Chemicals?
1. The following instruments measure to what place value?
Beaker:_____; Graduated Cylinder:_____; Buret:_____
a. Ones (1)
b. Tens (10)
c. Tenths (.1)
d. Hundredths (.01)
2. In the measurement 0.936 L, circle the estimated digit?
3. The diameter of a carbon atom is 0.000364 m. What is the diameter expressed in scientific notation?
4. Solve the following equation. Be sure to maintain SIGFIGS!
12.338 x 19 =
5. Describe correctly whether the bulls eye is accurate, precise, or both.
6. Accurately measure the volume of liquid in the graduated cylinder using proper
significant figures.
7. Given the density of silver is 20.5 g/cm3, what is the mass of 5.6 cm3 of silver? Answer to the
correct number of significant figures.
8. Convert 52045 mm to km.
Unit 2 – What Do Atoms Look Like?
9. True or false, ionic compounds have a low melting point?
10. If a neutral isotope has a mass number of 31 and contains 16 protons, how many neutrons does this neutral
isotope have?
11. What element is represented by the Aufbau diagram?
12. True or false, all atoms of the same element have the same number of protons.
13. Correctly calculate the average atomic mass for the element below given the element’s
abundance of the isotopes.
Isotopes of an Element
Abundance (%)
Mass (amu)
65.06
41.98
20.74
42.98
14.20
45.98
14. The letter “s” in the symbol 4s2 indicates which of the following?
Spin of electrons OR Speed of electrons OR Orbital shape
15. How many neutrons are in the following elements (fill in the blanks)?
75
a.
As has ___ neutrons
33
b.
19
F has ___ neutrons
9
c.
238
U has ___ neutrons
92
d.
24
Mg has ___ neutrons
12
16. In a neutral atom, the proton # equals the _________________ #, which is why the atom is neutral.
Matching: For questions 17-20, match the description on the right to the correct group on the left.
17.
18.
19.
20.
Stable; do not form ions
Forms +1 charge
Forms -1 charge
Includes Ca, Mg, Ba
a.
b.
c.
d.
Halogens
Noble Gases
Alkali Metals
Alkaline Earth Metals
21. Put the following in order from increasing atomic radius: Cation, Anion, Atom
22. Find the error in the following electron configurations?
a. 1s2 2s2 2p6 3s5
b. 1s8 2s2 2p6
c. [Ne] 4s2 4p6
23. What causes the shielding effect to remain constant across a period?
a. The charge on the nucleus is constant across a period so all atoms have the same radius in that period.
b. Electrons are added to the same principle energy level, while proton pull increases across a period, so
the atomic radius decreases across a period.
c. Electrons are added to different principal energy levels, while proton pull decreases across a period, so
the atomic radius increases across a period.
d. The atomic radius increases across a period because the mass of the atoms increases across a period.
Unit 3 – How Do Atoms Stick Together?
24. List ALL 7 diatomic molecules?
25. Which is the cation in the chemical NaCl?
26. In an ionic compound are electrons shared OR transferred?
27. How many valence electrons does Helium have?
28. Which combination of elements would be expected to produce the most polar covalent bonds?
O – Cl OR O – H
29. Which atom below has the greatest electronegativity? As, P, S, Se
30. How many sulfur atoms are in the following formula: Pb(SO4)2?
31. What is the correct chemical name for CCl3?
32. What is the correct chemical name for Fe2S3?
33. Which is the correct chemical name for KMnO4?
For questions 34-38, find the molecular shape and angle.
34. H2O
35. BF3
36. PH3
37. SiH4
38. F2
39. Elements with the same number of valence electrons are found in the same row or the same column?
40. Which molecule has two unshared pairs of electrons on the central atom? You already drew the structures
from #’s 34-38!
a. PH3
b. SiH4
c. H2O
d. F2
e. BF3
Unit 4 – What Happens When Chemicals Are Put Together?
41. One mole of any substance is equal to how many particles of that substance? (Hint: Avogadro’s #)
42. True or false, 22.4 L represents the volume of 6.02 x 1023 molecules of O2 gas @ STP?
43. Explain how to calculate the molar mass of a compound.
44. Find the molar mass for NaOH?
45. How many moles are in 300.0 grams of CO2?
46. What is the percent composition of ethane (C2H6)? Round to the nearest whole number.
47. Which of the following compounds have the same empirical formula?
a. C2H2 and C6H6
b. C2H6 and C2H4
c. C3H9 and C2H9
d. C12H22O11 and C6H12O6
48. What is the mass of 200.0 L of O2?
49. What is the mass of 3.80 x 1022 particles of potassium sulfate in grams?
50. If you have 0.5 moles of salt (NaCl) and 0.5 moles sugar C12H22O11), what will be the same about these two
samples?
a. The masses of the samples
b. The number of particles in each sample
c. The volume of the samples
d. The molar masses of the samples