Biology, 7e (Campbell)
Chapter 2: The Chemical Context of Life
Chapter Questions
1) About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter?
A) carbon, sodium, chlorine, nitrogen
B) carbon, sulfur, phosphorus, hydrogen
C) oxygen, hydrogen, calcium, sodium
D) carbon, hydrogen, nitrogen, oxygen
E) carbon, oxygen, sulfur, calcium
Answer:
Topic: Concept 2.1
Skill: Knowledge
2) Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates?
A) nitrogen
B) calcium
C) iodine
D) sodium
E) phosphorus
Answer:
Topic: Concept 2.1
Skill: Knowledge
3) Which of the following statements is false?
A) Atoms of the various elements differ in their number of subatomic particles.
B) All atoms of a particular element have the same number of protons in their nuclei.
C) The neutrons and protons present in the nucleus of an atom are almost identical in mass; each has a mass of about 1 dalton.
D) An atom is the smallest unit of an element that still retains the properties of the element.
E) Protons and electrons are electrically charged particles. Protons have one unit of negative charge, and electrons have one unit of positive charge.
Answer:
Topic: Concept 2.2
Skill: Knowledge
4) Each element is unique and different from other elements because of the number of protons in the nuclei of its atoms. Which of the following indicates the number of protons in an atom's nucleus?
A) atomic mass
B) atomic weight
C) atomic number
D) mass weight
E) mass number
Answer:
Topic: Concept 2.2
Skill: Knowledge
5) The mass number of an element can be easily approximated by adding together the number of ________ in an atom of that element.
A) protons and neutrons
B) energy levels
C) protons and electrons
D) neutrons and electrons
E) isotopes
Answer:
Topic: Concept 2.2
Skill: Comprehension
6) What is the approximate atomic mass of an atom with 16 neutrons, 15 protons, and 15 electrons?
A) 15 daltons
B) 16 daltons
C) 30 daltons
D) 31 daltons
E) 46 daltons
Answer:
Topic: Concept 2.2
Skill: Comprehension
7) Oxygen has an atomic number of 8 and a mass number of 16. Thus, the atomic mass of an oxygen atom is
A) exactly 8 grams.
B) exactly 8 daltons.
C) approximately 16 grams.
D) approximately 16 daltons.
E) 24 amu (atomic mass units).
Answer:
Topic: Concept 2.2
Skill: Comprehension
8) The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen?
A) The nitrogen atom has a mass number of approximately 7 daltons and an atomic mass of 14.
B) The nitrogen atom has a mass number of approximately 14 daltons and an atomic mass of 7.
C) The nitrogen atom has a mass number of 14 and an atomic mass of 7 grams.
D) The nitrogen atom has a mass number of 7 grams and an atomic number of 14.
E) The nitrogen atom has a mass number of 14 and an atomic mass of approximately 14 daltons.
Answer:
Topic: Concept 2.2
Skill: Comprehension
9) Calcium has an atomic number of 20 and an atomic mass of 40. Therefore, a calcium atom must have
A) 20 protons.
B) 40 electrons.
C) 40 neutrons.
D) A and B only
E) A, B, and C
Answer:
Topic: Concept 2.2
Skill: Comprehension
10) An atom with an atomic number of 9 and a mass number of 19 would have an atomic mass of approximately
A) 9 daltons.
B) 9 grams.
C) 10 daltons.
D) 20 grams.
E) 19 daltons.
Answer:
Topic: Concept 2.2
Skill: Comprehension
11) Different atomic forms of an element contain the same number of protons but a different number of neutrons. What are these different atomic forms called?
A) ions
B) isotopes
C) neutronic atoms
D) isomers
E) radioactive atoms
Answer:
Topic: Concept 2.2
Skill: Knowledge
12) How do isotopes of the same element differ from each other?
A) number of protons
B) number of electrons
C) number of neutrons
D) valence electron distribution
E) amount of radioactivity
Answer:
Topic: Concept 2.2
Skill: Knowledge
13) Which of the following best describes the relationship between the atoms described below?
Atom 1 Atom 2
A) They are isomers.
B) They are polymers.
C) They are isotopes.
D) They contain 1 and 3 protons, respectively.
E) They each contain 1 neutron.
Answer:
Topic: Concept 2.2
Skill: Comprehension
14) Which of the following best describes the relationship between the atoms described below?
Atom 1 Atom 2
A) They are both radioactive.
B) They are both phosphorus cations.
C) They are both phosphorus anions.
D) They are both isotopes of phosphorus.
E) They contain 31 and 32 protons, respectively.
Answer:
Topic: Concept 2.2
Skill: Comprehension
15) One difference between carbon-12 and carbon-14 is that carbon-14 has
A) two more protons than carbon-12.
B) two more electrons than carbon-12.
C) two more neutrons than carbon-12.
D) A and C only
E) B and C only
Answer:
Topic: Concept 2.2
Skill: Comprehension
16) 3H is a radioactive isotope of hydrogen. One difference between hydrogen-1 and hydrogen-3 is that hydrogen-3 has
A) one more neutron and one more proton than hydrogen-1.
B) one more proton and one more electron than hydrogen-1.
C) one more electron and one more neutron than hydrogen-1.
D) two more neutrons than hydrogen-1.
E) two more protons than hydrogen-1.
Answer:
Topic: Concept 2.2
Skill: Comprehension
17) The atomic number of carbon is 6. Carbon-14 is heavier than carbon-12 because the atomic nucleus of carbon-14 contains _____ neutrons.
A) 6
B) 7
C) 8
D) 12
E) 14
Answer:
Topic: Concept 2.2
Skill: Comprehension
18) Two isotopes of the same element will have different numbers of
A) protons.
B) neutrons.
C) electrons.
D) protons and neutrons.
E) neutrons and electrons.
Answer:
Topic: Concept 2.2
Skill: Comprehension
19) Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that
A) an electron may move to an electron shell farther out from the nucleus.
B) an electron may move to an electron shell closer to the nucleus.
C) the atom may become a radioactive isotope.
D) the atom would become a positively charged ion, or cation.
E) the atom would become a negatively charged ion, or anion.
Answer:
Topic: Concept 2.2
Skill: Knowledge
20) The atomic number of neon is 10. Therefore, which of the following is correct about an atom of neon?
A) It has 8 electrons in its outer electron shell.
B) It is inert.
C) It has an atomic mass of 10 daltons.
D) A and B only
E) A, B, and C are correct.
Answer:
Topic: Concept 2.2
Skill: Comprehension
21) From its atomic number of 15, it is possible to predict that the phosphorus atom has
A) 15 neutrons.
B) 15 protons.
C) 15 electrons.
D) 8 electrons in its outermost electron shell.
E) B and C only
Answer:
Topic: Concept 2.2
Skill: Comprehension
Figure 2.1
22) Which drawing depicts the electron configuration of neon ?
Answer:
Topic: Concept 2.2
Skill: Comprehension
23) Which drawing depicts the electron configuration of oxygen ?
Answer:
Topic: Concept 2.2
Skill: Comprehension
24) Which drawing depicts the electron configuration of nitrogen ?
Answer:
Topic: Concept 2.2
Skill: Comprehension
25) Which drawing is of an atom with the atomic number of 6?
Answer:
Topic: Concept 2.2
Skill: Comprehension
26) Which drawing depicts an atom that is inert or chemically unreactive?
Answer:
Topic: Concept 2.2
Skill: Comprehension
27) Which drawing depicts an atom with a valence of 3?
Answer:
Topic: Concept 2.2
Skill: Comprehension
28) Which drawing depicts an atom with a valence of 2?
Answer:
Topic: Concept 2.2
Skill: Comprehension
29) What does the reactivity of an atom depend on?
A) number of valence shells in the atom
B) number of orbitals found in the atom
C) number of electrons in each orbital in the atom
D) presence of unpaired electrons in the outer valence shell of the atom
E) presence of hybridized orbitals in the atom
Answer:
Topic: Concept 2.2
Skill: Knowledge
30) Atoms whose outer electron shells contain eight electrons tend to
A) form ionic bonds in aqueous solutions.
B) form covalent bonds in aqueous solutions.
C) be stable and chemically nonreactive, or inert.
D) be unstable and chemically very reactive.
E) be isotopes and very radioactive.
Answer:
Topic: Concept 2.2
Skill: Knowledge
31) What are the chemical properties of atoms whose valence shells are filled with electrons?
A) They form ionic bonds in aqueous solutions.
B) They form covalent bonds in aqueous solutions.
C) They are stable and chemically unreactive or inert.
D) They exhibit similar chemical behaviors.
E) C and D only
Answer:
Topic: Concept 2.2
Skill: Knowledge
Use the information extracted from the periodic table in Figure 2.2 to answer the following questions.
Figure 2.2
32) How many electrons does nitrogen have in its valence shell?
A) 2
B) 5
C) 7
D) 8
E) 14
Answer:
Topic: Concept 2.2
Skill: Comprehension
33) How many electrons does phosphorus have in its valence shell?
A) 1
B) 2
C) 3
D) 4
E) 5
Answer:
Topic: Concept 2.2
Skill: Comprehension
34) How many neutrons are present in the nucleus of a phosphorus atom?
A) 8
B) 15
C) 16
D) 31
E) 46
Answer:
Topic: Concept 2.2
Skill: Comprehension
35) How many electrons does an atom of sulfur have in its valence shell?
A) 4
B) 6
C) 8
D) 16
E) 32
Answer:
Topic: Concept 2.2
Skill: Comprehension
36) Based on electron configuration, which of these elements would exhibit chemical behavior most like that of oxygen?
A) carbon
B) hydrogen
C) nitrogen
D) sulfur
E) phosphorus
Answer:
Topic: Concept 2.2
Skill: Application
37) How many electrons would be expected in the outermost electron shell of an atom with atomic number 12?
A) 1
B) 2
C) 4
D) 6
E) 8
Answer:
Topic: Concept 2.2
Skill: Comprehension
38) The atomic number of each atom is given to the left of each of the elements below. Which of the atoms has the same valence as carbon ?
A) 7nitrogen
B) 9flourine
C) 10neon
D) 12magnesium
E) 14silicon
Answer:
Topic: Concept 2.2
Skill: Application
39) What is the valence of an atom with six electrons in its outer electron shell?
A) 1
B) 2
C) 3
D) 4
E) 5
Answer:
Topic: Concept 2.2
Skill: Comprehension
40) Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed to complete the valence shell of a fluorine atom?
A) 1
B) 3
C) 5
D) 7
E) 9
Answer:
Topic: Concept 2.2
Skill: Comprehension
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