C
HAPTER
R
EVIEW
C
HAPTER
R
EVIEW
USING KEY TERMS
1.What group of elements do Ca, Be, and Mg belong to?
2.What group of elements easily gains one valence electron?
3.What category do most of the elements of the periodic table fall under?
4.What is the term for the energy released when an atom gains an electron? 5.What are elements 90–103 called? 6.Give an example of a nuclear reaction.
Describe the process by which it takes place. 7.What are elements in the first group of the
periodic table called?
8.What atomic property affects periodic trends down a group in the periodic table? 9.What two atomic properties have an
increasing trend as you move across a period?
10.Write a paragraph describing in your own words how synthetic elements are created. Discuss
what modification has to be made to the equipment in order to synthesize super-heavy elements.
11.Which group of elements has very high ionization energies and very low electron affinities?
12.How many valence electrons does a fluorine atom have?
13.Give an example of an alloy.
UNDERSTANDING KEY IDEAS
How Are Elements Organized?14.How was Moseley’s arrangement of the elements in the periodic table different from Mendeleev’s?
15.What did the gaps on Mendeleev’s periodic table represent?
16.Why was Mendeleev’s periodic table accepted by most chemists?
17. What determines the horizontal arrange-ment of the periodic table?
18.Why is barium, Ba, placed in Group 2 and in Period 6?
Tour of the Periodic Table
19.Why is hydrogen in a class by itself? 20.All halogens are highly reactive. What
causes these elements to have similar chemical behavior?
21.What property do the noble gases share? How do the electron configurations of the noble gases give them this shared property? 22.How do the electron configurations of the
transition metals differ from those of the metals in Groups 1 and 2?
23.Why is carbon, a nonmetal element, added to iron to make nails?
24.If an element breaks when it is struck with a hammer, could it be a metal? Explain. 25.Why are the lanthanides and actinides
placed at the bottom of the periodic table? 26.Explain why the main-group elements are
also known as representative elements.
WRITING
SKILLS
C
HAPTER
R
EVIEW
4
REVIEW ANSWERS
1. alkaline-earth metals
2. halogens
3. metals
4. electron affinity
5. actinides
6. answers should involve the
transmutation of one element
to another by a change in the
number of protons in its nucleus.
7. alkali metals
8. electron shielding
9. electronegativity and ionization
energy
10. Answers should discuss particle
accelerators and the colliding
of particles at very high speeds
to produce elements of higher
atomic numbers.
11. noble gases
12. seven
13. Answers may include brass, steel,
sterling silver, pig iron, etc.
14. Moseley arranged the elements
according to their atomic
num-bers, while Mendeleev had
arranged them based on their
atomic mass.
15. He left gaps for the elements that
he predicted would be discovered
and which would have certain
properties.
16. His success in predicting the
properties of elements that
had not yet been discovered
gave him credibility.
17. The completion of an energy
level determines the points at
which the elements begin new
periods.
18. It has two valence electrons and
six occupied energy levels.
19. With only one proton and one
electron, hydrogen does not
exhibit the same properties
shared by the elements making
up any of the groups in the
peri-odic table.
4
4
Assignment Guide
Section
Questions
1
12, 14–18, 40, 42, 52, 57
2
1–3, 5, 7, 13, 19–26, 41, 44–46, 48, 50,
51, 55
3
4, 8, 9, 11, 27–33, 43, 47, 49, 54,
58–64
4
6, 10, 34, 39, 56
150
20. All halogens have seven valence
electrons and are therefore one
electron short of having a full
valence shell. As a result, they
readily react to acquire this one
electron.
21. Noble gases do not normally
react with other elements because
of the stability resulting from
their electron configurations.
22. The outer electrons of Groups 1
and 2 are in s orbitals. The outer
electrons of the transition metals
are in d orbitals and s orbitals.
23. Pure iron is too soft to make
nails. Adding carbon produces a
harder alloy.
24. Some metals are brittle.
Therefore, this element may be
a metal if it is shown to be an
excellent conductor of electricity.
25. This arrangement keeps the
periodic table conveniently
narrow.
26. They exhibit all the properties
characteristic of the elements.
27. Ionization energy slightly
decreases as you move down a
group and increases significantly
as you move across a period.
Increased distance from the
nucleus allows removal of an
electron using less energy.
28. Because an electron cloud has no
definite boundary, an exact radius
is impossible to measure.
29. As electrons are added across
a period, they are entering the
same principal energy level. The
increasing nuclear charge pulls
these electrons closer, making
the atoms progressively smaller
across a period. As electrons are
added down a group, they are
entering another principal energy
level, thus increasing the size of
the atom.
30. Electron affinity generally
increases because the effective
nuclear charge increases. Electron
shielding does not play a role
because electrons are not added
to inner energy levels.
REVIEW ANSWERS
continued
Trends in the Periodic Table
27.What periodic trends exist for ionization energy? How does this trend relate to different energy levels?
28.Why don’t chemists define atomic radius as the radius of the electron cloud that sur-rounds a nucleus?
29.How does the periodic trend of atomic radius relate to the addition of electrons? 30.What happens to electron affinity as you
move across a period beginning with Group 1? Why do these values change as they do? 31.Identify which trend diagram below
describes atomic radius.
32.What periodic trends exist for electronega-tivity? Explain the factors involved. 33.Why are the melting and boiling points of
mercury almost the lowest of the elements in its period?
Where Did the Elements Come From? 34.How does nuclear fusion generate energy? 35.What happens in the nucleus of an atom
when a transmutation takes place? 36.Why are technetium, promethium, and
neptunium considered natural elements even though they are not found on Earth? 37.Why must a synchrotron be used to create
a superheavy element?
38.What role did supernovae play in creating the natural elements?
39.What two elements make up most of the matter in a star?
MIXED REVIEW
40.Without looking at the periodic table, identify the period and group in which each of the following elements is located. a.[Rn]7s1
b.[Ar]4s2
c.[Ne]3s23p6
41.Which of the following ions has the electron configuration of a noble gas: Ca+or Cl−? (Hint: Write the electron configuration for each ion.)
42.When 578 kJ/mol of energy is supplied, Al loses one valence electron. Write the electron configuration of the ion that forms. 43.Name three periodic trends you encounter
in your life.
44.How do the electron configurations of the lanthanide and actinide elements differ from the electron configurations of the other transition metals?
45.Use the periodic table to describe the chem-ical properties of the following elements: a.iodine, I b.krypton, Kr c.rubidium, Rb Increases Increases Decreases Decreases Decreases Increases a. b. c.
151
in the periodic table. Does strontium share more properties with yttrium or barium? Explain your answer.
54.Examine the following diagram.
Explain why the structure shown on the right was drawn to have a smaller radius than the structure on the left.
ALTERNATIVE ASSESSMENT
55.Select an alloy. You can choose one men-tioned in this book or find another one by checking the library or the Internet. Obtain information on how the alloy is made. Obtain information on how the alloy is used for practical purposes.
56.Construct a model of a synchrotron. Check the library and Internet for information about synchrotrons. You may want to contact a synchrotron facility directly to find out what is currently being done in the field of synthetic elements.
57.In many labeled foods, the mineral content is stated in terms of the mass of the element, in a stated quantity of food. Examine the product labels of the foods you eat. Determine which elements are represented in your food and what function each ele-ment serves in the body. Make a poster of foods that are good sources of minerals that you need.
CONCEPT MAPPING
58.Use the following terms to create a concept map: atomic number, atoms, electrons,
ele-ments, periodic table,and protons.
46.The electron configuration of argon differs from those of chlorine and potassium by one electron each. Compare the reactivity of these three elements, and relate them to their electron configurations.
47.What trends were first used to classify the elements? What trends were discovered after the elements were classified in the periodic table?
48.Among the main-group elements, what is the relationship between group number and the number of valence electrons among group members?
CRITICAL THINKING
49.Consider two main-group elements, A and B. Element A has an ionization energy of 419 kJ/mol. Element B has an ionization energy of 1000 kJ/mol. Which element is more likely to form a cation?
50.Argon differs from both chlorine and potas-sium by one proton each. Compare the elec-tron configurations of these three elements to explain the reactivity of these elements. 51.While at an amusement park, you inhale
helium from a balloon to make your voice higher pitched. A friend says that helium reacts with and tightens the vocal cords to make your voice have the higher pitch. Could he be correct? Why or why not? 52.In his periodic table, Mendeleev placed Be,
Mg, Zn, and Cd in one group and Ca, Sr, Ba, and Pb in another group. Examine the elec-tron configurations of these elements, and explain why Mendeleev grouped the el-ements this way.
53.The atomic number of yttrium, which fol-lows strontium in the periodic table, exceeds the atomic number of strontium by one. Barium is 18 atomic numbers after stron-tium but it falls directly beneath stronstron-tium
31. c
32. Electronegativity decreases as
you move down a group because
of the increasing electron
shield-ing and increases as you move
across a period because of the
increasing effective nuclear
charge.
33. Because the d orbitals are
com-pletely filled, mercury forms
weaker bonds than most of the
other elements in Period 6.
34. The mass of the fused nuclei is
less than that of the mass of the
nuclei that created it. This mass
is converted to energy during
fusion.
35. The number of protons either
increases or decreases during a
nuclear reaction, producing a
different element.
36. These elements can be found
elsewhere in the universe and
are therefore natural.
37. Only a synchrotron can accelerate
nuclei to energies high enough to
result in fusion involving massive
nuclei.
38. Elements heavier than iron were
formed in supernovae.
39. hydrogen and helium
40. a. Period 7, Group 1
b. Period 4, group 2
c. Period 3, group 18
41. Cl
–42. [Ne]3s
243. Answers will vary but could
include, for example, the pattern
of seasons, the repeating school
year, the progression of weeks,
or the pattern of daily meals.
44. The lanthanide and actinide
elements have partially filled
f-electron shells.
45. a. A nonmetal in Group 17, it
needs one electron to achieve
a noble-gas configuration,
which means it is likely to
react with elements with
which it can obtain one
elec-tron, such as an alkali metal.
It has a high ionization energy,
and thus the formation of
pos-continued
b. A nonmetal of low reactivity
in Group 18, it has a filled
outer-energy level, so there
is little tendency to lose, gain,
or share electrons.
c. A reactive metal in Group 1,
it has a low ionization energy
because the loss of an electron
to form a positive ion gives
it a noble-gas configuration.
46. Argon has a complete energy
level of electrons, and therefore
is not reactive. Chlorine’s
elec-tron configuration is one short
of a full shell, so it has a
ten-dency to react with elements
from which it can gain one
electron. Potassium has only
a single valence electron, so it
readily reacts to lose that electron.
47. Elements were first classified by
reactivity and atomic mass. The
modern periodic table has trends
of atomic size, electron
configura-tion, ionization energy, and
elec-tron affinity, among other factors
not covered in this chapter.
48. Groups 1 and 2 have the same
number of valence electrons as
their group number. Groups
13–18 have n–10 valence
elec-trons, n being the group number.
49. Element A is more likely to lose
an electron and become a cation
because it has a lower ionization
energy.
50. As a noble gas with a full valence
shell, 3s
23p
6, argon is unreactive.
Chlorine has one less electron
than argon, 3s
23p
5, so it tends to
react by gaining one electron to
form an anion with a 1– charge.
Potassium has one more electron
than argon, 3s
23p
64s
1, so it tends
to react by losing one electron to
form a cation with a 1+ charge.
Answers continued on p. 155A–B
Atomic radius (pm) 250 200 150 100 50 0 Group number 1 2 13 14 15 16 17 18 Cs Rb K Na Li H He Period 6 Period 5 Period 4 Period 3 Period 2 Period 1
Atomic Radii of Main-Block Elements
TECHNOLOGY AND LEARNING
65. Graphing Calculator
Graphing Atomic Radius Vs. Atomic Number
The graphing calculator can run a program that graphs data such as atomic radius ver-sus atomic number. Graphing the data within the different periods will allow you to discover trends.
Go to Appendix C.If you are using a TI-83 Plus, you can download the program and data sets and run the application as directed. Press the APPS key on your calculator, then choose the application CHEMAPPS. Press 8, then highlight ALL on the screen, press 1, then highlight LOAD and press 2 to load the data into your calculator. Quit the applica-tion, and then run the program RADIUS. For
L1, press 2nd and LIST, and choose ATNUM.
For L2, press 2nd and LIST and choose
ATRAD.
If you are using another calculator, your teacher will provide you with keystrokes and data sets to use.
a.Would you expect any atomic number to have an atomic radius of 20 pm? Explain. b.A relationship is considered a function if it
can pass a vertical line test. That is, if a verti-cal line can be drawn anywhere on the graph and only pass through one point, the relation-ship is a function. Does this set of data repre-sent a function? Explain.
c.How would you describe the graphical rela-tionship between the atomic numbers and atomic radii?
FOCUS ON GRAPHING
Study the graph below, and answer the questions that follow.
For help in interpreting graphs, see Appendix B, “Study Skills for Chemistry.” 59.What relationship is represented in the
graph shown?
60.What do the numbers on the y-axis represent?
61.In every Period, which Group contains the element with the greatest atomic radius?
62.Why is the axis representing group number drawn the way it is in going from Group 2 to Group 13?
63.Which period shows the greatest change in atomic radius?
64.Notice that the points plotted for the elements in Periods 5 and 6 of Group 2 overlap. What does this overlap indicate?
153
REVIEW ANSWERS
continued
• Chapter Test
4
UNDERSTANDING CONCEPTS
Directions (1–4):For each question, write on a separate sheet of paper the letter of the correct answer.
1
Which of the following elements is formed in stars?A. curium C. gold
B. einsteinium D. mendelevium
2
Why are the Group 17 elements, the halogens, the most reactive of the nonmetal elements?F. They have the largest atomic radii. G. They have the highest ionization energies. H.They are the farthest right on the periodic
table.
I. They require only one electron to fill their outer energy level.
3
Which of the following is a property of noble gases as a result of their stable electron configuration?A. large atomic radii B. high electron affinities C. high ionization energies D. a tendency to form both cations
and anions
4
Which of these is a transition element?F. Ba H.Fe
G. C I. Xe
Directions (5–7):For each question, write a short response.
5
How did the discovery of the elements that filled the gaps in Mendeleev’s periodic table increase confidence in the periodic table?6
Why is iodine placed after tellurium on the periodic table if the atomic mass of tellurium is less than that of iodine?7
What is the outermost occupied energy level in atoms of the elements in Period 4?READING SKILLS
Directions (8–10):Read the passage below. Then answer the questions.
The atomic number of beryllium is one less than that of boron, which follows it on the peri-odic table. Strontium, which is directly below beryllium in period 5 of the periodic table has 34 more protons and 34 more electrons than beryllium. However, the properties of beryllium resemble the much larger strontium more than those of similar-sized boron.
8
The properties of beryllium are more similar to those of strontium than those of boron becauseA. A strontium atom is larger than a boron atom.
B. Strontium and beryllium are both reactive nonmetals.
C. A strontium atom has more electrons than a boron atom.
D. Strontium has the same number of valence electrons as beryllium.
9
Beryllium and strontium are both located in the second column of the periodic table. To which of these classifications do they belong? F. alkali metalsG. alkaline earth metals H. rare earth metals I. transition metals