Download Chapter 2.4 Periodic properties of the elements

Chapter 2.4
Periodic properties of
the elements
Electron Configurations, Atomic Properties, and
Periodic Trends
As we move down the periodic table the electron
configuration becomes longer and more complex.
This goes beyond the purpose of our course.
Electron configurations help to determine the atomic and chemical
properties of the elements. Properties such as atomic radius,
ionization energy, electron affinity and electronegativity
are periodic as they follow recurring trends in the periodic table.
React moderately to
form basic oxides
with the general
formula MO.
React slowly in
cold water,
generating H2(g)
and forming a
strong base,
M(OH)2.
React quickly
generating H2(g).
Electron Configurations, Atomic Properties, and
Periodic Trends
Group 13
Reaction
Group 1
Al displaces H2(g)
Al reacts readily
React slowly.
Periodic
Trends in Reactivity
of Metals
from steam.
if the protective
Aluminum forms an
coating
Withoxide
oxygen
in that
the air
protects the metal;
2O3 the
React rapidlythe
to compound
form oxidesAlwith
can act as a base or
general formula
M2O. These compounds
an acid.
coating is
Withoxide
water
removed, to
.
React vigorouslygenerate
with coldH2(g)
water,
The reaction is dangerously
generating H2(g) and forming a
are strong bases.
strong base with the general
Group 14
The most
metallic
C and Si are nonformula
MOH. Sn and Pb react
slowly
to form
elements,
Sn
and
metals,
and
form
Group 2
React moderately to form basic oxides
React slowly in cold
water,
Pb, dogenerating
not react H2(g)Hand
acidic
oxides.
Ge
2(g) .forming a
with the general
formula
MO.
with water.
is a metalloid, and
strong base, M(OH)2.
forms an acidic oxide.
Group 13
React slowly. Aluminum forms an oxide Al displaces H2(g) from steam.
SnO2 can act as an
coating that acid
protects
the metal; the
or a base. PbO2
compound Alis2O
can
act as a base or an
3
unreactive.
acid.
Transition Metals Zn is the most
Zn and
Femost metallic
Znelements,
reacts readily
Group 14
C and Si are non- metals, and form acidic
The
Sn
(for example, Fe, reactive transition
displace H2(g)
to generate H2(g),
oxides. Ge is a metalloid, and forms an
and Pb, do not react
with water.
Co, Ni, Cu, Zn,
metal, and forms ZnO from steam. Fe
Cu, Ag, and Au
acidic oxide. SnO2 can act as an acid or a
Ag, Au)
when the metal is
rusts slowly at
do not react.
base. PbO2 is unreactive.
burned in air. Ag and room temperature.
Transition Metals (for
Zn is the most
transition metal, Zn and Fe displace H2(g)
Aureactive
do not react.
example, Fe, Co, Ni, Cu, and forms ZnO when the metal is burned from steam. Fe rusts slowly at
Zn, Ag, Au)
in air. Ag and Au do not react.
room temperature.
Magnesium ribbon reacting
with oxygen in air
Potassium reacting
with water
Reaction with dilute
acids
Nickel reacting with
dilute acid
violent, igniting H2(g)
generated.
React quickly generating
H2(g).
Al reacts readily if the
protective oxide coating is
removed, to generate H2(g) .
Sn and Pb react slowly to
form H2(g).
Zn reacts readily to generate
H2(g), Cu, Ag, and Au do not
react.
Atomic Radius
can determine it by measuring the distance between the nuclei of bonded,
neighbouring atoms. For example, for metals, atomic radius is half the
distance between neighbouring nuclei in a crystal of the metal element.
For elements that occur as molecules, which is the case for many nonmetals, atomic radius is half the distance between nuclei of identical
atoms that bonded together with a single covalent bond. In Figure 3.23,
the radii of metallic elements represent the radius of an atom in a metallic
crystal. The radii of all other elements represent the radius of an atom of
the element participating in a single covalent bond with one additional,
like atom.
The size of an atom, its atomic radius, decreases across a period. Furthermore, atomic radii
generally increase down a group. Two factors affect differences in atomic radii:
1
(IA)
H
2
(IIA)
3
(IIIA)
4
(IVA)
5
(VA)
6
(VIA)
7
(VIIA)
Li 152 Be 112
B
Na 186 Mg 160
Al 143 Si 118 P
K
Ga 135 Ge 122 As 120 Se 119 Br 114 Kr 112
85 C
77 N
75 O
73 F
72 Ne 71
2
110
S 103 Cl 100 Ar 98
3
Period
2.The other factor that affects atomic radii is
changing nuclear charge — specifically, the
effective nuclear charge (the net force of
attraction between electrons and the nucleus)
He 31
37
1
1.As n increases, there is a higher probability of
finding electrons farther from their nucleus.
Therefore, the atomic volume is larger.
8
(VIIIA)
227 Ca 197
4
Rb 248 Sr 215
In 167 Sn 140 Sb 140 Te 142 I
Cs 265 Ba 222
Tl 170 Pb 146 Bi 150 Po 168 At (140) Rn (140)
133 Xe 131
5
6
Fr (270) Ra (220)
7
3
(IIIB)
4
(IVB)
5
(VB)
6
(VIB)
7
(VIIB)
8
9
(VIIIB)
10
11
(IB)
12
(IIB)
Sc 162 Ti 147 V 134 Cr 128 Mn 127 Fe 126 Co 125 Ni 124 Cu 128 Zn 134
4
Y 180 Zr 160 Nb 146 Mo 139 Tc 136 Ru 134 Rh 134 Pd 137 Ag 144 Cd 151
5
La 187 Hf 159 Ta 146 W 139 Re 137 Os 135 Ir 136 Pt 138 Au 144 Hg 151
6
First Ionization Energy
The energy needed to completely remove one electron from a ground state gaseous atom is called the
ionization energy. Energy must be added to the atom to remove an electron in order to overcome
the force of attraction exerted on the electron by the nucleus.
Since multi-electron atoms have two or more electrons, they also have more than one ionization
energy.
For calcium the first ionization energy (IE1), is 599 kJ/mol:
Ca(g) + 599 kJ → Ca+(g) + eThe second ionization energy (IE2) is the amount of energy required to remove the second electron.
For calcium, it may be represented as:
Ca+(g) + 1145 kJ → Ca2+1(g) + eFor a given element, IE2 is always greater than IE1 because it is always more difficult to remove a
negatively charged electron from a positively charged ion than from the corresponding neutral atom.
Ionization energies measure how strongly electrons are bound to atoms. Ionization always requires energy to
remove an electron from the attractive force of the nucleus.
Low ionization energies indicate easy removal of electrons, and hence easy positive ion (cation) formation.
First Ionization Energy
Every element exhibits a large increase in ionization energy when an inner electron is
removed.
SECTION 7.4
Ionization
Energy
This supports the idea that only the outermost electrons are involved
in the
chemical
bondings and
reactions. The inner electrons are too tightly bound to the
GO FIGURE
nucleusWhich
to has
bea lost
from
theenergy,
atom
even shared with another atom.
larger first
ionization
Ar or or
As? Why?
1A
Ba
503
2A
Lu
524
Zr
640
Hf
659
V
Cr
651
Mn
653
Fe
717
Nb
Co
763
Mo
652
760
Ni
Tc
684
Ru
Ta
737
Zn
Cu
702
Rh
W
710
761
906
746
P
d
7
770
Re
2
0 8
Os
Ag
04
760
Cd
Ir
840
731
868
880
Pt
Au
870
Hg
890
1007
N
1402
O
1314
F
1681
Ar
Cl
1521
Si 10 P
Al
S
12
786
578
1000 1251
As
Ge
Kr
Ga
Br
947
Se
762
1351
579
941 1140
Sn
In
Sb
558
Te
709
Xe
834
I
869 1008 1170
Tl
Pb
589
716
Bi
Po
Rn
703
812
1037
Incre
asing
! FIGURE 7.9
B
801
C
1086
ioniz
ation
3A
ener
Trends in first ionization energies of the elements.
gy
4A
5A
gy
Cs
376
Y
600
Ti
659
Ne
2081
ener
Sr
549
Rb
403
Sc
633
tion
Ca
590
K
419
He
2372
Mg
738
easi
ng io
niza
Na
496
Be
899
6A
7A
Trends in first ionization energies of the elements.
8A
Incr
Li
520
Ionization energy (kJ/mol)
H
1312
261
ctrons
crease in effective nuclear charge causes the outermost electrons to be held more tightly,
making them harder to remove. The first ionization energies therefore generally increase
from left to right across the periodic table. The reason for the trend in first ionization ener-
First Ionization Energy
Period 2
st ionization
elements
The noble
rst ionization
etals have low
s. Note the
ions for the
rough 10,
3 elements,
as for the
. Variations for
ot nearly so
or
First ionization energy (kJ/mol)
2500
Period 3
Period 4
He
Ne
2000
F
H
1000
Ar
N
1500
C
Be
O
Mg
0
5
Si
10
Zn
S
Na Al
Li
Br
P
B
500
Kr
Cl
15
As
Fe Ni
Se
Cr
Ti
Ca
Ge
Sr
Mn Co Cu
Sc V
Ga
K
Rb
20
25
Atomic number
30
35
© Cengage Learning.
ning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
First ionization energies vs atomic number for the first 38 elements of the P.T.E.
y suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
The noble gases have very high IE1 while the 1A metals (Li, Na, K and Rb) have low IE1.
Note the similarities in the variations for the Period 2 elements to those for the Period 3 elements.Variations for B group elements
are not nearly so pronounced as those for A group elements.
12/7/12 4:56
Electron affinity
The first ionization energy of an atom is a measure of the energy change when removing an electron
from the atom to form a cation.
For example, the first ionization energy of Cl(g), 1251 kJ/mol, is the energy change associated
with the process
Cl(g) + 1251 kJ → Cl+(g) + e[Ne]3s23p5
[Ne]3s23p4
The positive ionization energy means that energy must be put into the atom to remove the
electron.
Most atoms can also gain electrons to form anions. The energy change that occurs when an electron is
added to a gaseous atom is called the electron affinity because it measures the attraction, or affinity,
of the atom for the added electron.
For most atoms, energy is released when an electron is added
For example, the addition of an electron to a chlorine atom is accompanied by an energy
change of -349 kJ/mol, the negative sign indicating that energy is released during the process
Cl(g) - 349 kJ → Cl-(g) - e[Ne]3s23p5
[Ne]3s23p6
Therefore the electron affinity of Cl is -349 kJ/mol.
Ionization energy measures the ease with which an atom loses an electron,
whereas electron affinity measures the ease with which an atom gains an electron.
Electron affinity
For the electron affinity the trends through the P.T.E. are not as evident as they are for ionization
264
CHAPTER 7 Periodic Properties of the Elements
energy.
The halogens, which miss one electron to complete the p orbital, have the most negative electron
Thehas
fact
that the electron
affinity is p
affinities. By gaining an electron, a halogen atom forms a stable anion that
a noble-gas
configuration.
GO FIGURE
to an Ar atom; the Ar - ion is unstabl
Which
of thegas
groups
shown
here
The addition of an electron
to a noble
requires
that the
electron reside
in a higher-energy
orbital
! FIGURE
7.11 shows
the elec
the most
negative
electronorbital isthe
that is empty in the atom.has
Because
occupying
a higher-energy
energetically
unfavorable,
thethat the
first five periods.
Notice
electron affinity is highly positive.
affinities? Why does this make
energy. The halogens, which are one
sense?
negative electron affinit
1A
stable anion that has a
8A
tion of an electron to a n
H
He
!73 2A
in a higher-energy sub
4A
6A
7A " 0
3A
5A
Because occupying a hi
Ne
F
O
N
C
B
Be
Li
!27 !122 " 0 !141 !328 " 0
!60 " 0
the electron affinity is h
are positive for the same
Ar
Cl
S
P
Si
Al
Na Mg
ously empty p subshell t
!43 !134 !72 !200 !349 " 0
!53 " 0
The electron affinit
Br
Se
As
Ga Ge
Kr
K
Ca
Because these elements
!30 !119 !78 !195 !325 " 0
!48 !2
must be put in an orb
I
Te
Sb
Sn
In
Xe
Rb
Sr
electron–electron repul
!30 !107 !103 !190 !295 " 0
!47 !5
affinities that are eithe
Electron affinity
for some
elements
$ FIGURE
7.11in kJ/mol
Electron
affinity
in
affinities of their neighb
kJ/mol for selected s- and p-block
we saw a discontinuity in the trends
elements.
Electron affinities do not chang
Metals, Nonmetals and Metalloids
With the exception of the noble gases, however, none of the elements exist in
nature as individual atoms. The elements can be broadly grouped,
considering
SECTION 7.6
Metals, Nonmeta
the properties, as metals, nonmetals, and metalloids.
GO FIGURE
Notice that germanium, Ge, is a metalloid but tin, Sn, is a metal. What changes
in atomic properties do you think are important in explaining this difference?
Increasing metallic character
Increasing metallic character
1A
1
1
H
2A
2
3
Li
4
Be
11
Na
12
Mg
19
K
20
Ca
3B
3
21
Sc
4B
4
22
Ti
5B
5
23
V
6B
6
24
Cr
7B
7
25
Mn
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
55
Cs
56
Ba
71
Lu
72
Hf
73
Ta
87
Fr
88
Ra
103
Lr
104
Rf
Metals
Metalloids
Nonmetals
" FIGURE 7.12
8B
3A
13
5
B
4A
14
6
C
5A
15
7
N
6A
16
8
O
7A
17
9
F
8A
18
2
He
10
Ne
2B
12
30
Zn
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
26
Fe
9
27
Co
10
28
Ni
1B
11
29
Cu
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cp
113
114
115
116
117
118
57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
8
Metals, metalloids, and nonmetals.
Metals, Nonmetals and Metalloids
Characteristic Properties of Metals and Nonmetals
Metals
•Have a shiny luster; various colors, although
most are silvery
•Solids are malleable and ductile
•Good conductors of heat and electricity
•Most metal oxides are ionic solids that are
basic
•Tend to form cations in aqueous solution
Nonmetals
•Do not have a luster; various colors
•Solids are usually brittle; some are hard, some are
soft
•Poor conductors of heat and electricity
•Most nonmetal oxides are molecular substances
that form acidic solutions
•Tend to form anions or oxyanions in aqueous
solution
2
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
4
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
Metals
06
g
9
Pr
1
Pa
107 108 109 110 111 112 113 114 115 116 117 118
Most
metallic
elements
Bh
Hs
Mt Ds
Rg Cp exhibit the shiny luster and conduct heat and electricity. In general
they are malleable (can be pounded into thin sheets) and ductile (can be drawn into wires).
60
61
63
62
65
66
67
68
69
70
All
are
solids
at64room
temperature
except mercury.
Nd Pm Sm Eu Gd Tb Dy Ho
Er
Tm Yb
Two
metals
93
94 (Cs
95 and
96 Ga
97 ) melt
98
99above
100 room
101 102temperature. At the other extreme, many metals have very
92
Np Pu Am Cm Bk
Cf
Es
Fm Md No
U
high melting temperatures. For example, chromium melts at 1900 °C.
loids, and nonmetals.
SECTION 7.7
Trends for Group 1A and Group 2A Metals
269
• Someto
Properties
of the
Alkali Metals
Metals tend to have lowTABLE
IE and7.4tend
form
cations.
+ and that on
alkali metal
ionElectron
in metals,
a compound
Melting is always
Density 1 , Atomic
I1 any alkaline earth metal is
bitsThe
the charge
physicalon
andany
chemical
properties
of
the
3
Element
Configuration
Point (°C)
(g/cm )
Radius (Å)
(kJ/mol)
+
2 ,inthat
is, the
s electrons
are easily lost.
Asalways
indicated
Figure
7.12,outer
metallic
character1 generally
181
0.53
1.34
520
[He]2s
SECTION 7.6
Metals,
Nonmetals,
and
Metalloids
265
Compounds
madetable
up and
ofLithium
a
metal
and
a
nonmetal
tend
to
be
ionic
substances
group
of the periodic
decreases
as
we
proceed
1
Sodium
98
0.97
1.54
496
[Ne]3s
1
examine
the close relationships
that exist[Ar]4s
between
elec-63
Potassium
0.86
1.96
419
GO FIGURE
1
Rubidium
39
1.53
2.11
[Kr]5s
operties
metals,
nonmetals,
andbut
metalloids.
Among
the fundamental
atomic
properties
(radius,
electron configuration, etc.),403first ionization energy is the best
otice
that of
germanium,
Ge, is a metalloid
tin,
Sn, is a metal.
What changes
1
Cesium
28
[Xe]6s this difference?
atomic
properties
do you thinkan
areelement
important
in
explaining
indicator
of whether
behaves
as a metal
or
Increasing metallic character
1.88
2.25
a nonmetal.
376
Group 1A: The Alkali Metals 8A
18
alkali metals
metals are (soft
! FIGURE
7.19). All have characteristic metallic
2
t theH1 shiny
luster we associateThewith
! metallic
FIGURE
2A
4A
6A (7A
3A
5A solids
He
2
14 metallic
16luster
17 and
13
15
properties,
such
as
a
silvery,
high
thermal and electrical conductivity.
nd electricity.
In general they are malleable
(can
5
9
10
8
6
7 be
4
3
The name alkali comesBfrom
“ashes.” Many compounds of sodium
Ne
O word
F meaning
N
C an Arabic
Be
Li
8B potassium,
ductile
(can
be
drawn
into
wires).
All
are
solids
at
room
and
two
alkali
metals,
were
isolated
from
wood
ashes by early chemists.
13
18
16
17
14
15
12
11
4B
6B
7B
1B
2B
3B
5B
Al
Cl
Ar
S
P
Si
Na Mg
8
9 As10
4
6
7
11
12
3
5
TABLE 7.4
the
alkali metals have low densities and melting points, and
melting
point
=22 -2339 24°C)25, which
is 28a"liquid
at 31shows,
room
tem27
30
35
36
29
34
32
33
26
20
19
21
these
properties
vary
in
a
fairly
regular
way
with
increasing atomic number. We see the
Co cesium
Ga Ge
Ni
Cu Zn
Se
Br
Kr
As
Ti
Cr Mn Fe
V temperature,
Ca
K
Sc room
lightly
above
at
28.4
°C
and
the group,
46
48 move
52
54 as increasing atomic radius and decreas47as we
53 such
50
51
49 down
45 trends
40
43
39
42
44 usual
41
38
37
Pdionization
Ag Cdtemperatures.
Te metal
I of
Xeany given period has the lowest I value in
Sn
In
Zr metals
Y
Ru ing
Nb Mo Tc
Sr
Rb
r extreme,
many
melt
atRhfirst
very
high
energy.
TheSbalkali
1
78
80
84
85
86
79
83
82
81
71
77
75
72
74
76
73
56
55
the
period
(Figure
7.9),
which
reflects
the
relative
ease
with
which
its
outer
s
electron
at 1900
°C
.
Po
Rn
Au Hg
At
Pt
Bi
Tl
Pb
Lu Hf
Ir
Re
W
Os
Ta
Cs Ba
can
be
removed.
As
a
result,
the
alkali
metals
are
all
very
reactive,
readily
losing
one
elec88
87
103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118
nization
and
therefore
tend
to
form
Bh7.9)
Hs tron
Mt toDs
Rg
Cp
Rf (Figure
Db Sg
Fr Ra energies
Lr
form ions carrying a 1+ charge. •(Section 2.7)
sult, Metals
metals are57 oxidized
(lose
electrons)
when
they
un-69only70as compounds. Sodium and potassium are relaThe
alkali
metals
exist
in nature
60
61
63
62
64
65
66
67
68
58
59
tively
in
in seawater,
Nd Pm
Eu Gd (radius,
Sm abundant
TbEarth’s
Dy crust,
Ho
Er
Tm Yb and in biological systems, usually as the cations
Ce
Pr
La
ng the
fundamental
atomic
properties
electron
Metalloids
89
93 of 94
96
97 All
98 alkali
99 metals
100 101combine
102
90
91
92
ionic95compounds.
directly with most nonmetals. For example,
Np energy
Pu Am is
Cm
Bkbest
Cf indicator
Es
Fm Md No
Pa
U
and Nonmetals
so forth),AcfirstThionization
the
" FIGUREElemental
7.19 Sodium,
Metals
aresulfides:
shiny and
Nalike the other
they react with hydrogen to form hydrides"
andFIGURE
with sulfur
to form
7.13
Metals
aremalleable
shiny and
alkali
metals,
is
soft
enough
to be cut with
as
a metal
a nonmetal.
FIGURE
7.12 or
Metals,
metalloids, and nonmetals.
malleable.
1A
1
Nonmetals
the oxide of a metal, we expect it to be an ionic solid. Indeed it
oint of 2485 °C.
has a 3+ charge, Sc3+, and the oxide ion is O2- . Consequently,
Nonmetals can be solid, liquid, or gas. They are not lustrous and generally are poor
e is Sc2O3. Metal oxides tend to be basic and, therefore, to react
conductors
and electricity.
Their melting
points are generally low (although diamond,
ater.
In this case theof
saltheat
is scandium
nitrate, Sc(NO
3)3:
a form of C, melts at 3570 °C).
HNO3(aq) ¡ 2 Sc(NO3)3(aq) + 3 H2O(l)
Under ordinary conditions, seven nonmetals exist as diatomic molecules. Five of these are gases (H2,
N2, O2, F2, and Cl2), one is a liquid (Br2), and one is a volatile solid (I2). Excluding the noble gases, the
E remaining nonmetals are solids that can be either hard, such as diamond, or soft, such as sulfur
SECTION
265 Metals, Nonmetals, and Metalloids
SECTION 7.6
quation for the reaction between copper(II)
oxide 7.6
and Metals,
sulfuricNonmetals, and Metalloids
Because of their relatively large electron affinities, nonmetals tend to gain electrons and form anions
GH
O2O(l)
Fmetals.
I G U R EFor example, the reaction of aluminum with bromine produces the ionic
q) ¡
(aq) +with
whenCuSO
they4react
, Ge, is a metalloid
but tin,
Sn,
is a metal. Ge,
What
Notice
that
germanium,
is changes
a metalloid but tin, Sn, is a metal. What changes
compound aluminum
bromide:
o you think are important
in properties
explaining do
thisyou
difference?
in atomic
think are important in explaining this difference?
2 AlIncreasing
+ 3 Brmetallic
2 → 2 AlBr3(s)
character
Increasing metallic character
Increasing metallic character
1A
1
1
H
2A
2
3A
13
5
B
4A
14
6
C
5A
15
7
N
6A
16
8
O
7A
17
9
F
8A
18
2
He
3A
13
5
B
4A
14
6
C
5A
15
7
N
6A
16
8
O
7A
17
9
F
8A
18
2
He
d, or gas. They are not lustrous and generally are poor
con10
10
4
3
Ne
Be generally lower than Ne
Li are
ty. Their melting
points
those
of
8B
18 8B
13
18
16
17
14
15
11 1B 12 2B 3B 13 4B 14 5B 15 6B 16 7B 17
6B
7B
5B
2B
a5 form
of7 carbon,
is10 Na
an11exception
and
melts at 3570 °C10). 1B
Al
Cl
Ar
S
P
Si
Mg 12 3 Al 4 Si
8
9
6
11
12
5 P 6 S 7 Cl 8 Ar 9
27exist
35 26 36
28 19as
29 diatomic
32 23 33 24 34 25Five
24nonmetals
25
26
23
31
30
35
36
28
29
34
32
33
20 30 21 31 22 molecules.
even
of27these
Co
Ni K Cu Ca Zn Sc Ga Ti Ge V As Cr SeMn Br Fe Kr Co
Cr Mn Fe
V
Ni
Cu Zn Ga Ge
Se
Br
Kr
As
d41Cl242
), one
(Br
),48and
is 51a 42volatile
solid
46 37
52 43 53 44
54 45 (I46
47 238
45
43 is44a liquid
2). 47 48 49 50 51 52 53 54
40 50 41
39 49one
Pd Rb Ag Sr Cd Y In Zr SnNb SbMo Te Tc I Ru Xe Rh
Ru Rh
Nb Mo Tc
Pd Ag Cd
Te
I
Xe
Sb
Sn
In
e73 remaining
nonmetals
are solids that can be either hard,
78 55 79 56 80 71 81 72 82 73 83 74 84 75 85 76 86 77
77
75
74
76
78
80
84
85
86
79
83
82
81
Pt Cs Au
Ir
Re (!
Os FIGURE
Ba Hg
hTaas W
sulfur
7.16
).Lu Tl Hf Pb Ta Bi W Po Re At Os Rn Ir Pt Au Hg Tl Pb Bi Po At Rn
known
the 117
medieval
world as
106 107 108 109 110 87 11188 112 103113104114105115106116107117108118109 110 111 112 Sulfur,
113 114
115 to116
118
y105
negative
affinities,
nonmetals
tend
to
gain
"
FIGURE
7.16
Sulfur,
known
Bh
Hs Mtelectron
Ds Fr RgRa
Cp Lr
Sg
Dblarge,
Bh
Hs Mt Ds Rg Cp
Rf Db Sg
“brimstone,” is a nonmetal. to the
th metals. For example, the reaction of aluminum with medieval world as “brimstone,” is a
60
61
63 Metals
62composed
64
65entirely
66 57 67 58
58 Compounds
59
63
62 typically
64
65molecular
66
67 substances
68
69
70 that tend to be gases,
59 69 60 70 61 are
of68nonmetals
Nd aluminum
Pm Sm Eu bromide:
Gd Tb Dy La Ho Ce Er Pr TmNd YbPm Sm Eu Gd nonmetal.
Ce
Pr
ompound
Tb Dy Ho
Er
Tm Yb
Metalloids
solids
temperature.
hydrocarbons
we use for fuel
93 low-melting
94
95
96
97
98 89at
99 room
90 liquids,
91
92 or
94
95E.g.
96the
97 common
98
99
100
101 102
90 100 91 101
92 102 93
Np Pu Am Nonmetals
Cm Bk
Cf Ac Es Th Fm Pa Md U NoNp Pu Am Cm Bk
Th
Pa
U
Cf
Es
Fm Md No
Al(s)(methane,
+ 3 Br2(l)CH
2 AlBr3C
(s)3H8; octane, C8H18) and
[7.12]
¡
the gases HCl, NH3, and H2S.
4; propane,
metalloids, and nonmetals.
" FIGURE 7.12 Metals, metalloids, and nonmetals.
ll gain enough electrons to fill its
Metalloids
Metalloids have properties intermediate between those of metals and those of
nonmetals. They may have some characteristic metallic properties but lack others.
E.g. Silicon looks like a metal, but it is brittle rather than malleable and does not conduct heat or
electricity nearly as well as metals do
Several metalloids, e.g. Silicon, are electrical semiconductors and are
the principal components of circuits and computer chips. One of the
reasons is that their electrical conductivity is intermediate between
that of metals and that of nonmetals.
Elemental Si looks metallic but is brittle and
has low thermal
electrical conductivity.
! FIGURE
7.18 andElemental
silicon.
Although it looks metallic, silicon, a
metalloid, is brittle and a poor thermal
and electrical conductor.
Very pure silicon is an electrical insulator, but its conductivity can be dramatically increased with the
addition of specific impurities called dopants. This modification provides a mechanism for controlling the
electrical conductivity by controlling the chemical composition.