1. Atoms, Molecules, and Life2
Atoms, Molecules, and Life

2. Which is the smallest unit of organization?
Cell
Atom
Organelle
Organ
Question: 2-1
Answer: b
Diff: Easy
Text Ref: Section 2.1
Skill: Factual
Also relates to: Chapter 1
Notes:
This question serves both as a review from the last chapter and as a link to this chapter. It will get students thinking about atoms.

3. Which is the smallest unit of organization?
Cell
Atom
Organelle
Organ
Question: 2-1
Answer: b
Diff: Easy
Text Ref: Section 2.1
Skill: Factual
Also relates to: Chapter 1
Notes:
This question serves both as a review from the last chapter and as a link to this chapter. It will get students thinking about atoms.

4. If an atom has 15 protons and 15 neutrons in its nucleus, how many electrons does it have?2 4 8 15
Question: 2-2
Answer: d
Diff: Easy
Text Ref: Section 2.1
Skill: Factual
Notes:
This question reinforces the fact that the properties and reactivity of atoms depend on the number of subatomic particles. There are generally the same number of electrons in atoms as there are protons making them electrically neutral.

5. If an atom has 15 protons and 15 neutrons in its nucleus, how many electrons does it have?2 4 8 15
Question: 2-2
Answer: d
Diff: Easy
Text Ref: Section 2.1
Skill: Factual
Notes:
This question reinforces the fact that the properties and reactivity of atoms depend on the number of subatomic particles. There are generally the same number of electrons in atoms as there are protons making them electrically neutral.

6. An inert element __________.
forms covalent bonds with itself
has a full outer electron shell
has an empty outer electron shell
does not react with other elements because it is unstable
Question: 2-3
Answer: b
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question reinforces the fact that the number and position of the electrons affects the reactivity of the atom.

7. An inert element __________.
forms covalent bonds with itself
has a full outer electron shell
has an empty outer electron shell
does not react with other elements because it is unstable
Question: 2-3
Answer: b
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question reinforces the fact that the number and position of the electrons affects the reactivity of the atom.

8. The electrical attraction between positively and negatively charged ions forms a(n) ___________.
covalent bond
hydrogen bond
ionic bond
oxygenated bond
Question: 2-4
Answer: c
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
If students can remember this, it will be easier for them to understand the different types of bonds.

9. The electrical attraction between positively and negatively charged ions forms a(n) ___________.
covalent bond
hydrogen bond
ionic bond
oxygenated bond
Question: 2-4
Answer: c
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
If students can remember this, it will be easier for them to understand the different types of bonds.

10. How many electrons does sodium have in its outer shell?1 2 4 8
Question: 2-5
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question will prepare students for a discussion on ions and ionic bonds. It is important to ask them if it is easier for sodium to lose one electron or to gain seven to achieve a full outer electron shell.

11. How many electrons does sodium have in its outer shell?1 2 4 8
Question: 2-5
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question will prepare students for a discussion on ions and ionic bonds. It is important to ask them if it is easier for sodium to lose one electron or to gain seven to achieve a full outer electron shell.

12. After sodium loses an electron, it is a(n) ___________.
positive ion
negative ion
neutral ion
isotope
Question: 2-6
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
When sodium donates an electron from its outer electron shell to chloride, the sodium atom becomes a positively charged atom called an ion and its outer electron shell is completely empty.

13. After sodium loses an electron, it is a(n) __________.
positive ion
negative ion
neutral ion
isotope
Question: 2-6
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
When sodium donates an electron from its outer electron shell to chloride, the sodium atom becomes a positively charged atom called an ion and its outer electron shell is completely empty.

14. How many electrons does chlorine have in its outer shell?1 2 4 7
Question: 2-7
Answer: d
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question continues to provide background for understanding the ionic bond that forms salt. Have students draw out the atomic structure of chlorine. It is important to ask them if it is easier for chlorine to lose seven electrons or to gain one in order to achieve a full outer electron shell.

15. How many electrons does chlorine have in its outer shell?1 2 4 7
Question: 2-7
Answer: d
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question continues to provide background for understanding the ionic bond that forms salt. Have students draw out the atomic structure of chlorine. It is important to ask them if it is easier for chlorine to lose seven electrons or to gain one in order to achieve a full outer electron shell. 15

16. After chlorine gains an electron, it is a(n) ___________.
positive ion
negative ion
neutral ion
isotope
Question: 2-8
Answer: b
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Upon accepting an electron from sodium, chlorine becomes a negatively charged atom called an ion and its outer electron shell is filled with electrons.

17. After chlorine gains an electron, it is a(n) ___________.
positive ion
negative ion
neutral ion
isotope
Question: 2-8
Answer: b
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Upon accepting an electron from sodium, chlorine becomes a negatively charged atom called an ion and its outer electron shell is filled with electrons.

18. How many electrons does sodium lose to chlorine to form an ionic bond?1 2 4 8
Question: 2-9
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question goes an extra step; it will confirm the students’ understanding of the final outcome of the ionic bond formed to make salt.

19. How many electrons does sodium lose to chlorine to form an ionic bond?1 2 4 8
Question: 2-9
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
This question goes an extra step; it will confirm the students’ understanding of the final outcome of the ionic bond formed to make salt.

20. What is the difference between a nonpolar covalent bond and a polar covalent bond?
A polar covalent bond results when there is unequal sharing of electrons in a molecule, whereas electrons are shared equally in a nonpolar covalent bond.
A nonpolar covalent bond is positively charged and a polar covalent bond is negatively charged.
A polar covalent bond is positively charged and a nonpolar covalent bond is negatively charged.
A polar covalent bond results when an atom has more electrons than protons; a nonpolar covalent bond occurs when atoms have the same number of electrons and protons.
Question: 2-10
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Explain that covalent bonds are different from ionic bonds because they share electrons. Break the discussion into two sections: one on nonpolar covalent bonds and one on polar covalent bonds.

21. What is the difference between a nonpolar covalent bond and a polar covalent bond?
A polar covalent bond results when there is unequal sharing of electrons in a molecule, whereas electrons are shared equally in a nonpolar covalent bond.
A nonpolar covalent bond is positively charged and a polar covalent bond is negatively charged.
A polar covalent bond is positively charged and a nonpolar covalent bond is negatively charged.
A polar covalent bond results when an atom has more electrons than protons; a nonpolar covalent bond occurs when atoms have the same number of electrons and protons.
Question: 2-10
Answer: a
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Explain that covalent bonds are different from ionic bonds because they share electrons. Break the discussion into two sections: one on nonpolar covalent bonds and one on polar covalent bonds.

22. How many electrons does oxygen have in its outer shell?1 2 4 6
Question: 2-11
Answer: d
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Have students draw out the atomic structure of oxygen. In the next question, they will figure out why the structure allows oxygen to form a double nonpolar covalent bond.

23. How many electrons does oxygen have in its outer shell?1 2 4 6
Question: 2-11
Answer: d
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Have students draw out the atomic structure of oxygen. In the next question, they will figure out why the structure allows oxygen to form a double nonpolar covalent bond.

24. How many nonpolar covalent bonds does oxygen form with itself?1 2 4 8
Question: 2-12
Answer: b
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Talk about how molecular oxygen exists as O2. This will come up again in the chapters on photosynthesis and cellular respiration when students see that water splits into 1/2 O2 + 2 H+ + 2 electrons. It will help them understand why it is written as 1/2 O2 rather than just an O.

25. How many nonpolar covalent bonds does oxygen form with itself?1 2 4 8
Question: 2-12
Answer: b
Diff: Easy
Text Ref: Section 2.2
Skill: Factual
Notes:
Talk about how molecular oxygen exists as O2. This will come up again in the chapters on photosynthesis and cellular respiration when students see that water splits into 1/2 O2 + 2 H+ + 2 electrons. It will help them understand why it is written as 1/2 O2 rather than just an O. 25

26. What kind of bond holds the atoms of a single water molecule together?
Ionic
Polar covalent
Nonpolar covalent
Hydrogen
Question: 2-13
Answer: b
Diff: Easy
Text Ref: Section 2.3
Skill: Factual
Notes:
It is important to show students that ionic and covalent bonds hold the atoms of a molecule together, whereas hydrogen bonds are attractions between molecules. This question and the next illustrate how covalent bonds hold the atoms of a water molecule together, while hydrogen bonds hold water molecules together.

27. What kind of bond holds the atoms of a single water molecule together?
Ionic
Polar covalent
Nonpolar covalent
Hydrogen
Question: 2-13
Answer: b
Diff: Easy
Text Ref: Section 2.3
Skill: Factual
Notes:
It is important to show students that ionic and covalent bonds hold the atoms of a molecule together, whereas hydrogen bonds are attractions between molecules. This question and the next illustrate how covalent bonds hold the atoms of a water molecule together, while hydrogen bonds hold water molecules together.

28. What kind of bond forms between water molecules?
Ionic
Polar covalent
Nonpolar covalent
Hydrogen
Question: 2-14
Answer: d
Diff: Easy
Text Ref: Section 2.3
Skill: Factual
Notes:
Hydrogen bonds hold water molecules together, while polar covalent bonds hold the atoms within a single water molecule together.

29. What kind of bond forms between water molecules?
Ionic
Polar covalent
Nonpolar covalent
Hydrogen
Question: 2-14
Answer: d
Diff: Easy
Text Ref: Section 2.3
Skill: Factual
Notes:
Hydrogen bonds hold water molecules together, while polar covalent bonds hold the atoms within a single water molecule together.

30. When you sweat, what property of water is functioning to cool you off?
Water is adhesive.
Water has a high heat of vaporization.
Water has a high surface tension.
Water is neutral in pH.
Question: 2-15
Answer: b
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Notes:
Talk about how it takes a lot of energy (heat) to break the hydrogen bonds that hold water together.
This can also lead to a discussion on Calories.

31. When you sweat, what property of water is functioning to cool you off?
Water is adhesive.
Water has a high heat of vaporization.
Water has a high surface tension.
Water is neutral in pH.
Question: 2-15
Answer: b
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Notes:
Talk about how it takes a lot of energy (heat) to break the hydrogen bonds that hold water together.
This can also lead to a discussion on Calories.

32. The basilisk lizard takes advantage of this property of water as it runs along the surface of a pond or stream.
Water is adhesive.
Water has a high heat of vaporization.
Water has a high surface tension.
Water is neutral in pH.
Question: 2-16
Answer: c
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Notes:
All of the answers are correct statements, but # 3 is the only correct answer. Adhesion applies to the polarity of water and its ability to stick to other polar surfaces. Surface tension applies to the cohesion of water, the tendency of water molecules to stick to each other via hydrogen bond formation.
This question can be used to again illustrate hydrogen bonding, discussed earlier in Chapter 2, and how it contributes to the properties of water.

33. The basilisk lizard takes advantage of this property of water as it runs along the surface of a pond or stream.
Water is adhesive.
Water has a high heat of vaporization.
Water has a high surface tension.
Water is neutral in pH.
Question: 2-16
Answer: c
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Notes:
All of the answers are correct statements, but # 3 is the only correct answer. Adhesion applies to the polarity of water and its ability to stick to other polar surfaces. Surface tension applies to the cohesion of water, the tendency of water molecules to stick to each other via hydrogen bond formation.
This question can be used to again illustrate hydrogen bonding, discussed earlier in Chapter 2, and how it contributes to the properties of water.

34. Pure water is neutral in pH because __________.
the concentration of oxygen and hydrogen is equal
hydrogen bonding reduces the formation of hydrogen ions
ionization does not occur
the concentration of hydroxide ions and hydrogen ions is equal
Question: 2-17
Answer: d
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Notes:
This question reinforces the concept of ionization.

35. Pure water is neutral in pH because __________.
the concentration of oxygen and hydrogen is equal
hydrogen bonding reduces the formation of hydrogen ions
ionization does not occur
the concentration of hydroxide ions and hydrogen ions is equal
Question: 2-17
Answer: d
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Notes:
This question reinforces the concept of ionization.

36. Without buffers such as bicarbonate or phosphate, which property would be directly affected?
Living things respond to stimuli.
Living things maintain homeostasis.
Living things need energy.
Living things grow.
Question: 2-18
Answer: b
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Also relates to: Chapter 1
Notes:
This question will give students a chance to apply what they learned in Chapter 1 about the characteristics of life.
It is also a good follow-up question for talking about the importance of buffers to living things.
It seems that many students are familiar with the use of the pH scale and the importance of buffers in relation to swimming pool maintenance. This may, depending on your demographic, be a connection that they can relate to.

37. Without buffers such as bicarbonate or phosphate, which property would be directly affected?
Living things respond to stimuli.
Living things maintain homeostasis.
Living things need energy.
Living things grow.
Question: 2-18
Answer: b
Diff: Moderate
Text Ref: Section 2.3
Skill: Conceptual
Also relates to: Chapter 1
Notes:
This question will give students a chance to apply what they learned in Chapter 1 about the characteristics of life.
It is also a good follow-up question for talking about the importance of buffers to living things.
It seems that many students are familiar with the use of the pH scale and the importance of buffers in relation to swimming pool maintenance. This may, depending on your demographic, be a connection that they can relate to.

38. How many covalent bonds can be made by the carbon atom in the figure below?1 2 4 8
Question: 2-19
Answer: c
Diff: Moderate
Text Ref: Sections 2.1 and 2.2
Skill: Conceptual
Notes:
Because the carbon atom has four electrons in its outer shell, it can make four covalent bonds with other atoms until this shell is complete with eight electrons.
Figure 2-2, part 1

39. How many covalent bonds can be made by the carbon atom in the figure below?1 2 4 8
Question: 2-19
Answer: c
Diff: Moderate
Text Ref: Sections 2.1 and 2.2
Skill: Conceptual
Notes:
Because the carbon atom has four electrons in its outer shell, it can make four covalent bonds with other atoms until this shell is complete with eight electrons.
Figure 2-2, part 1