Arnoldi
Chemistry
Covalent Bonding
Review
1. How are most elements found in nature?
2. What do we call the chemical attachment between two atoms or ions?
3. Show on the atoms below how chemical bonds occur.
4. What do we call the energy required tobreak the bondsin a chemical compound?
5. What happens to bond energy when a bond is formed? Why?
6. What happens to bond energy when a bond is broken? Why?
7. Most atoms want to have ___electrons in their outer shell. A notable exception to this is Hydrogen, which only needs ___ electrons to have a full outer shell. The special rule that tells us this is the ______or______.
8. In every covalent bond, the electrons are ______between one atom andanother.
9. In a polar covalent bond, the electrons are shared ______between the two atoms.
10. In a nonpolar covalent bond, the sharing is ______between the two atoms.
11. In an ionic bond, the electrons are ______from on atom to the other.
12. A group of neutral atoms joined together by covalent bonds is called a(n) ______.
13. A molecule is the smallest piece of a/n ______compound that retains the characteristics of that compound.
14. A formula unit is the smallest piece of a/n ______compound that retains the characteristics of that compound.
15. What is a diatomic molecule?
16. What are the seven elements that are always found as diatomic molecules?
17. TRUE or FALSEWe can predict the formula unit that will always be produced from
the combination of two certain ions.
Explain your answer with a specific example.
18. TRUE or FALSEWe can predict the molecule that will always be produced from
the combination of two certain atoms.
Explain your answer with a specific example.
19. TRUE or FALSEA molecule always occurs in the lowest possible ratio of the
atoms that are combined.
Explain your answer with a specific example.
20. Hydrogen only needs two total electrons to maximize its stability. Explain why using a Bohr diagram.
21. Show the bonding that occurs in O2 using Bohr diagrams.
22. Show the process of bonding involved in CH4 using Lewis Dot Structures.
23. Use electronegativity differences to predict the type of bond (ionic, polar covalent, nonpolar covalent) in each of the following:
Explain your answer.
a. Calcium to Bromine
b. Phosporus to Chlorine
c. I2
d. NH3
24. Use the periodic table to predict the type of bond (ionic, polar covalent, nonpolar covalent) in each of the following:
Explain your answer.
a. Calcium to Bromine
b. Phosporus to Chlorine
c. I2
d. NH3
25. Covalent compounds are combinations of ______, ionic compounds are combinations of______.
26. Both covalent and ionic bonds are very STRONG (or) WEAK.
27. Compare INTER strengths between covalent and ionic bonding situations.
28. Explain why covalent compounds have lower melting and boiling points (as compared to ionic compounds).
29. Why don’t covalent compound conduct electricity?
30. Covalent compounds are ______, while ionic compounds are hard.
31. Covalent compounds are ______, while ionic compounds are brittle.
32. Covalent compounds have a ______, while ionic compounds have no odor.
33. Draw the Lewis Dot Structure for each of the following:
a. Sib. Sc. N
34. TRUE OR FALSEAll molecules exist in the same basic shape.
35. TRUE or FALSEAll molecules exist in a two-dimensional shape that can be easily shown in a Lewis Dot Structure.
36. What is the theory that is used to describe the molecular shapes that occur for different covalent substances?
37. What is the main goal in VESPR theory?
38. Based on VSEPR Theory which of the following shapes would you expect to occur if two atoms of element X covalently combined with one atom of element Y?
Explain your answer.
OR
39. What controls the polarity of a MOLECULE? (not a bond)
40. How are polar bonds and polar molecules alike?
41. How are polar bonds and polar molecules different?
42. What is the best way to determine if a molecule is polar or nonpolar?
43. What is an easier / quicker way to determine polarity in molecules with unpaired electrons on the central atom?
44. Strengths of (covalent) intermolecular attractions are based upon what characteristic?
45. Rank the following from strongest to weakest:
INTER ionic attractions(crystalline lattice)
attractions between polar molecules
attractions between nonpolar molecules
46. What phase will a substance be in at room temperature if it has really strong INTER forces?
47. What phase will a substance be in at room temperature if it has really weak INTER forces?
48. Draw the Lewis Dot Structure of each of the following:
a. Pl3(ignore the red circle)b. CH2F2
c. Br2d. C2H4l2
e. N2f. C3H6
g. C2H5OHh. C2H2
(hint… one of the H atoms is on the O)
49. Based on number 48, label PI3 (# 44a) as a polar or nonpolar molecule.
50. Based on number 48, give your best guess about the polar or nonpolar nature of the following molecules drawn in # 44:
c. Br2
e. N2
g. C2H5OH
h. C2H2
51. Based on your answers to # 45, 46, 47, 48, 49 and 50…
Which of the following will most likely be a gas at room temperature? Which is most likely to be a liquid? Which is most likely to be the solid? Explain your answer.
Sodium Chloride, NaClNitrogen, N2Ethanol, C2H5OH