Quiz 4 Review Sheet
Honors Biology
This is to be used to see if you are ready to take the quiz, not as a study guide.
Quiz 4 will cover:
Drawing molecules
Chapter 2 – 2.9 through 2.14
0.5 Make sure you can draw molecules. Like on the exam, I will give you a molecular
formula and you will need to draw a possible structural formula for it. I will not ask you
to draw valence shell electrons, but you should know how to.
1. Describe the structure of water in as much detail as possible including its
geometry, partial charges, etc…
2. Why are we so interested in water as opposed to any other molecule like methane
or pentanediol?
3. Define the term electronegativity.
4. Describe what makes one element more electronegative than another element.
For example why is oxygen more electronegative than carbon? Why is oxygen more
electronegative than sulfur?
5. In class we said that when two elements with very different electronegative
values form a covalent bond. This bond is more specifically called what? Explain
why this name is given to this bond (hint: Earth, magnets, personality disorder).
6. If two elements with similar electronegativity form a covalent bond, this bond is
called what? Compare this type of bond to the type of bond in question number 5.
7. List every polar covalent bond we spoke about in class (Ex. O-H). What makes
these bonds polar covalent?
8. List every non-polar covalent bond we discussed in class (Ex. O=O, C-C). What
makes these bonds non-polar?
9. In class we said that the C-H covalent bond is non-polar even thought carbon has
more protons than hydrogen. Explain why.
10. Is water a polar or non-polar molecule? Explain why.
11. You should be able to identify polar and non-polar covalent bonds in any
molecule I give you like we did in class.
12. Give one example of a non-polar molecule. Why is this molecule considered nonpolar?
13. Explain how multiple water molecules would interact with each other in a glass
of water.
14. Explain why a single water molecule can hydrogen bond to four other water
molecules.
15. What makes a hydrogen bond different from an ionic or covalent bond? Which is
stronger?
16. Explain why hydrogen bonds are able to form between two water molecules in
terms of the properties of the individual atoms that make up a water molecule.
17. ***I will ask you a question about this: You should now realize that the
properties of water or any molecule come from the interactions between the atoms
like O interacting with H to make a polar covalent bond. The interaction depends on
the valence shell electrons of each atom and the number of valence shell electrons
depends on the number of protons in the nucleus. Therefore, the properties of any
molecule/compound/element come from the nuclei of the very atoms that make
them up. We call this reductionist approach. In the end we will see that the
properties of all matter (including life) come from the subatomic particles that make
up that matter. All of the properties of water can be explained by looking at the
number of protons in the nuclei of oxygen and hydrogen.
(proton/neutron/electron arrangement leads to polarity, polarity leads to Hbonding, H-bonding leads to most properties of water)
18. When one pours salt into water, the salt “dissolves”. Explain what this means on
the atomic level. What does it mean to “dissolve”.
19. If I were to pour oil into water, the two substances do not mix. Explain why on
the molecular level. Why can water dissolve salt, but not oil?
20. What is meant by like dissolves like.
21. How is a water molecule held together? How are water molecules held to each
other?
22. In class we discussed many properties of water. The first was cohesion, which
leads to surface tension, a high specific heat, moderation of temperature,
evaporative cooling, and more. Describe cohesion and why it happens on the
molecular level. How does cohesion lead to each of the properties I mentioned?
23. The second property was adhesion. Adhesion allows water to be the “universal
solvent” and makes water extremely sticky. Describe adhesion on the molecular
level. What type of molecules would be involved in adhesion with water? Explain
how adhesion makes water the universal solvent. Draw a picture of a single sodium
atom surrounded by water to demonstrate adhesion, universal solvent and
dissolving all in one picture. Why is adhesion, like all the other properties, so
important for life on Earth as we know it?
24. Explain the difference between solution, aqueous solution, solvent and solute.
Give an example of a aqueous solution and identify the solvent and solute. Give an
example of a non-aqueous solution and do the same.
25. What is heat on the molecular level? Explain how you heat something up (on the
MOLECULAR LEVEL). Don’t just say I turn on the stove. What is the difference
between heat and temperature?
26. Explain why wood burns and why in order for wood to burn, molecular oxygen
needs to be present. Why does this process generate so much “heat”. Your
explanations need to be specific ones on the molecular level. The reductionist
approach is the only way to understand everything.
27. Explain the importance of water’s high specific heat for life on Earth. What does
it mean that water has a high specific heat? Why is this important in evaporative
cooling as well?
28. Explain how evaporative cooling works on the molecular level. Why does water
secreted onto your skin cool your body down if the water you are secreting is as
warm as your body?
29. Explain, on the molecular level, why ice is less dense that water and therefore
floats. Why is this unique property of water so important for life on Earth? What
would happen otherwise? Explain how the freezing of water can crack boulders on
the molecular level?
30. What does the quote “We may live on land, but our cells are marine” refer to?