14.
Practice Problems
Sc3+
[Ar]
1.
Maximum in sublevels, 2(2l +1)
s (l = 0) p (l = 1) d (l = 2) f (l = 3)
2
Level
n
1
2
2
6
3
2
6
10
4
2
6
10
Total
2n2
2
Cu
paramagnetic
1
0
0
ml
0
0
2
1
0
0
-1
1
0
1
0
2
-1
2
1
0
-1 -2
+½ +½ +½ +½ +½ +½ +½ +½ +½ +½ +½ +½ +½ +½
ms
-½ -½ -½ -½ -½ -½ -½ -½ -½ -½ -½ -½ -½ -½
a.
3, 2, 0, +½
3, 2, 0, -½
6
3.
1s-2s-2p-3s-3p-4s-3d-4p-5s-4d-5p-6s-4f-5d-6p-7s-5f-6d-7p
Halogen
Metal or
Nonmetal
Nonmetal
K
4
1
Alkali metal
metal
Be
2
2
Alkaline earth metal
metal
Ar
3
18
noble gas
nonmetal
5.
1
energy level
# of electrons
6.
magnesium
silicon
1s22s22p63s2
1s22s22p63s23p2
Iron
1s22s22p63s23p64s23d6
7.
[Ar] represent the 18 core electrons in n = 1 to n = 3
8.
emphasize filling order
[Kr]5s24d105p5
emphasize valence shell
[Kr]4d105s25p5
3d




Si
19.
Atomic Radius
decreases
Period Pattern left to right
no anomalies
Anomaly group numbers
Ionization Energy
increases
Period Pattern left to right
columns 2, 15 and 18
Anomaly group numbers
20. a.
The valence electron for Li is in the 2s sublevel, which
is closer to its nucleus than the valence electron for
Na, which is in the 3s sublevel.
b.
Si has 4 unshielded protons (protons – core
electrons), which attract the valence electrons closer
to the nucleus than the 3 unshielded protons in Al.
9.
1s 2s
2p
3s
3p
4s
S          
x
columns 13 and 16
Anomaly group numbers
Electron Affinity
decreases
Period Pattern left to right
2
s
sublevel
x
x
x
x
x
17.
4.
Group Name
Decrease
c.
Anions add electrons, which increases electronelectron repulsion.
9
3, __, __, +½
Period Group
Symbol
#
#
17
5
I
Increase
x
x
x
Cations lose an energy level  smaller.
b.
2,1, __, __
Cu+
diamagnetic
Mg
diamagnetic
Relative Size
Atoms from top to bottom
Cations from top to bottom
Anions from top to bottom
Atoms from left to right
Cations from left to right
Anions from left to right
Isoelectric ions from low Z to high Z
Size of cation compared to atom
Size of anion compared to atom
b.
32
3
1
Zn2+
[Ar]3d10
16. a.
18
2.
n
l
Ru3+
[Kr]4d5
15.
8
14
Ag+
[Kr]4d10

Co               
10.
Cr
Cu
Mo
Ag
[Ar]4s13d5
[Ar]4s13d10
[Kr]5s14d5
[Kr]5s14d10
11.
2,0,0,-½
2,1,1,-½
3,1,-1,½
4,0,0,½
3,2,2,½
12.
a
b
c
d
2, 0, 0, -½
3, 2, -2, +½
5, 1, 1, +½
4, 1, 0, -½
13.
cations
anions
K+, Ca2+, Sc3+
P3-, S2-, Cl-
c.
The ionized electron for B comes from the second
energy level, which is at a lower energy state than the
ionized electron from Al, which comes from the third
energy level  it takes more energy to ionize.
d.
The ionized electrons for Si and P come from the 3p
sublevel, but the attraction between the Si nucleus and
the ionized electron is less compared to P because Si
is larger than P  it takes more energy to ionize P.
e.
The ionized electron for Al comes from the 3p
sublevel, which is at a higher energy state than the
ionized electron for Mg, which comes from the 3s
sublevel  it takes less energy to ionize Al.
f.
The ionized electron for S comes from a fully occupied
3p orbital, which is at a higher energy state (greater ee repulsion) than the ½-filled 3p orbital of P's ionized
electron  it takes less energy to ionize S.
g.
8.
I2 is much larger than I1 because the second ionized
10.
electron comes from the core rather than valence
shell.
D
Valence electrons occupy the s and p sublevels.
Represents an atom of a transition metal.
Transition metals contain d sublevel electrons.
The second energy level contains only s and p
sublevels, not d.
11.
The first two electrons have relatively low ionization
energies. As a result, they are typically lost during
chemical reactions.
j.
The added electron to Mg must go into a higher energy
state (3p) compared Na (3s)  the loss in energy when
an electron approaches a nucleus is offset by the
electron's higher energy level.
k.
The added electron to P must go into an occupied porbital with e-e repulsion compared to Si, which has an
empty p-orbital  the loss in energy when an electron
approaches a nucleus is offset by the e-e repulsion.
l.
Although the added electrons for S and Cl enter
occupied p-orbitals, the Cl atom is smaller; therefore
the electron can get closer to the Cl nucleus, which
releases more energy.
m.
The added electron to Ar enters the 4s sublevel,
whereas the added electron to Cl enters the 3p sublevel
 the loss in energy when an electron approaches a
nucleus is offset by the higher energy level.
B
Halogen (column 17) anions have the electron
configuration of a noble gas (ns2np6).
12.
B
Alkaline earth (column 2) cations have the electron
configuration of a noble gas (ns2np6).
13.
A
Transition metal cations lose their s sublevel electrons
first then d sublevel electrons.
14.
A
Ions from atoms that are ± 3 of a noble gas (columns 1,
2, 3/13, 15, 16, 17) are isoelectronic (= electrons).
15.
C
Large energy gap between the 3rd and 4th electron,
 three valence electrons (column 3/13).
16.
C
protons increases, but energy level remains the same
 increasing attraction and decreasing radius.
17.
D
Core protons – core electrons is constant  nuclear
attraction  same as is radius.
18.
A
Electron affinity decrease (more negative) from left to
right, exceptions columns 2, 15 and 18  O
19.
D
Rb+ is too large to be considered. N3-, O2- and Mg2+are
isoelectric, but Mg2+ has the most protons.
20.
D
Paramagnetic = unpaired electrons  V (3 d electrons),
Co (3 d electrons), and As (3 p electrons).
21.
D
Practice Multiple Choice
Ionization energy and atomic mass increase, ionic
radius decreases then increases  atomic radius..
22.
1.
Hund's rule: maximum number of same spin electrons,
[He]2s() 2p( 
,  = paramagnetic.
A
The valence shell of S: 3s() 3p()(
unpaired electrons.

23.
2.
B
9.
C
h.
For Al, the first two ionized electron come from
different sublevels, which have a greater difference in
energy compared to Si, where the first two electrons
come from the same energy sublevel.
i.
C
B
Pauli: orbital can't have two electrons with the same
spin. Two spins = two electrons maximum.
C
The valence shell of Ga: 4s() 4p(
has one electron in the highest sublevel (4p).
3.
A
Practice Free Response
Heisenberg: limit to what we can know about an
electrons position and simultaneous velocity.
1.
4.
C
Electron 31: 4th
or 1 and ms = +½ or -½  (4, 1, 1, ½) fits
l
= -1, 0
5.
D
Configuration has 5 valence electrons, which puts it in
column 15,  N, P, As, Sb or Bi
6.
C
Unreactive chemicals have completed s and p
sublevels (noble gas).
7.
A
Excited states: orbital diagrams with gaps, where a
lower energy level orbital is vacant.
a.
The exact position and velocity of an electron is
unknowable.
b.
The full positive charge of the nucleus as felt by the
valence electrons is lessened by the core electrons.
C.
Electrons fill sublevels in such a way that there is a
maximum # of half filled orbitals.
2.
8.
a
b
3.
Mg
[Ne]3s2

3s
Cu
[Ar]4s13d10


P
[Ne]3s23p3

3s

3p
4s
3d
c
(3, 0, 0, -½)
(3, 2, -2, +½)
(3, 1, 0, ½)
2+ [Ne]
Cu+ [Ar]3d10
P3- [Ne]3s23p6
d Mg
a.
Sc3+, Ca2+, K+, Cl-, S2-, P3b.
Each ion has the same number of electrons (18), but
the number of protons decreases from Sc to P.
Therefore, the smallest ion is Sc3+ because it has the
greatest Zeff to the largest P3-.
4.
Al
Fe
Al3+
S
paramagnetic paramagnetic diamagnetic paramagnetic
5.
6.
Property
atomic radius
Si
1
P
2
S
3
Cl
4
ionization energy
4
2
3
1
2
1
3
4
electron affinity
a.
Element 2 has the lowest first-ionization energy.
Metals lose electrons to become ions, and element 2
requires the least energy to remove an electron.
b.
Magnesium. Element 3 has low first and second
ionization energies relative to the third ionization
energy, indicating that the element has two valence
electrons, which is true for magnesium.
c.
1s2 2s2 2p6 3s2
Electron configuration of element 3
Common ion charge of element 2
1+
Chemical symbol of element 2
Na
Element with the smallest atomic radius
Element 1
Al
Chemical symbol for element 4
7. a.
The valence energy levels for Li and Be are the same.
However, Be has 4 protons and Li has only 3 protons.
Therefore, the nuclear charge experienced by the
valence electrons is greater in Be than in Li (Zeff), so Be
has a smaller atomic radius.
b.
The electron added to K enters an s sublevel, whereas
the electron added to Ca enters a higher p energy
sublevel. As a result, the change in energy from K to Kis greater than from Ca to Ca-, thus a more negative
electron affinity.
c.
Although Se is a smaller atom than As (greater Zeff), the
electron removed from Se comes from a fully occupied
p-orbital, which has greater electron-electron repulsion
compared to the ionized electron from As, which
comes from a ½-filled p-orbital. The greater electronelectron repulsion for Se places that orbital in a higher
energy state  the ionization energy is less for Se
compared to As.
a.
5s2. Sr is in the 2nd column and 5th row  it has two s
electrons in the 5th energy level.
b.
Rb > Sr. Rb has an effective nuclear charge of +1
compared to Sr's +2  Rb has a weaker hold.
c.
Sr > Ca. Sr's valence electrons are in a higher energy
level (5) compared to Ca (4)  farther away.
d.
Ca > Sr > Rb. First ionization energy is inversely related
to atomic radius (farther away = weaker attraction).
e.
Sr > Sr2+. Sr outer energy level is the 5th, which is
removed when Sr becomes Sr2+.
f.
Br- > Sr2+. Br- and Sr2+ have the same number of
electrons, but Sr2+ has more protons.
g.
Second electron. The first two electrons are valence,
whereas the 3rd electron is core.
h.
Strontium is diamagnetic because it has all paired
electrons.
i. Compared to bromine, strontium is shinier/duller and a
better/worst conductor.