5: Homework Solutions
- Page ID
- 43939
1. Atoms share electrons to form covalent bonds. Two or more non-metals form covalent bonds. The presence of metals indicates an ionic compound.
2.
3. a)
b) C has 8 bonding electrons (4 shared pairs). O has 4 bonding electrons (2 shared pairs).
c) Yes for carbon and oxygen. Hydrogen only has a duet because it is a 1st shell element.
d) 2 single bonds and 1 double bond
e) Carbon and oxygen share one double bond. Carbon shares a single bond with EACH hydrogen atom.
4. a)
b) 6 bonding electrons (3 shared pairs) and 2 non-bonding electrons (1 lone pair)
c) 2 bonding electrons (1 shared pair) and 6 non-bonding electrons (3 lone pairs)
d) Nitrogen shares six electrons. All atoms have octets.
e) covalent
5.
Molecules because only one element is present.
6. a) 1 bond and 3 lone pairs
b) 4 bonds
c) 2 bonds and 2 lone pairs
d) 3 bonds and 1 lone pair
e) no bonds
7.
8. Expanded octet: more than 8 valence electrons. Phosphorus and sulfur can form expanded octets because their valence electrons occupy the 3rd shell.
9. a) dinitrogen tetroxide
b) sulfur hexachloride
c) carbon tetrabromide
d) diphosphorus pentoxide
e) chlorine heptafluoride
10.
11. The trigonal planar molecular shape has trigonal planar electron geometry with bond angles of 120° (2-D), whereas, the trigonal pyramidal molecular shape has tetrahedral electron geometry with bond angles of 109° (3-D).
12. a) 3-D b) 2-D c) 3-D d) 2-D e) 2-D
13. a) 109° b) 120° c) 109° d) 120° e) 180°
14. a) linear; 180° b) tetrahedral; 109° c) trigonal pyramidal; 109° d) trigonal planar; 120° e) bent; 120°
15.
16. a) The carbons sharing the double bond have trigonal planar molecular shape. The carbon with the triple bond has linear molecular shape.
b) 2-D
c) 120°
d) 120°
e) 180°
17 & 18 - Use your model kits to determine the answers.
19. a) oxygen
b) oxygen
c) chlorine
d) carbon
e) nitrogen
20. Electronegativity increases as we move up a column or left to right across a period.
21.
22. a) polar b) non-polar c) non-polar d) polar e) polar
23. No, while H-bonding is the strongest IMF, it is not a true chemical bond because the electrons are not shared to form a covalent bond or lost or gained to form ions.
24. The London Dispersion force is the weakest. It is also called van der Waals, induced dipole, or the hydrophobic interaction.
25. The strength of the IMF increases as the magnitude of the partial charge increases. The permanent dipole moments of polar compounds create the stronger dipole-dipole IMF compared to the weak, temporary interactions of non-polar compounds.
26. a) London dispersion
b) H-bonding
c) Dipole-dipole
d) dipole-dipole
e) H-bonding
27. H-bonding in the liquid phase draws the water molecules so close together that the density of liquid water is higher than solid water (ice). The crystal structure of the ice crystals forces the water molecules to stay further apart which lowers the density.
28. The two strands of DNA are held in the double helix by H-bonds. Since H-bonds are not true bonds, the double helix of DNA can open and close as information is needed by the cell.