Chemistry Reference
In-Depth Information
EXAMPLE 4.16
Write the electronic configurations of O, S, Se, Te. What feature makes them
have similar chemical properties?
Solution
1
s
2
2
s
2
2
p
4
O
1
s
2
2
s
2
2
p
6
3
s
2
3
p
4
S
1
s
2
2
s
2
2
p
6
3
s
2
3
p
6
4
s
2
3
d
10
4
p
4
Se
1
s
2
2
s
2
2
p
6
3
s
2
3
p
6
4
s
2
3
d
10
4
p
6
5
s
2
4
d
10
5
p
4
Te
ns
2
np
4
The configuration of the outermost (
n
th) shell is common to all the
group VIA elements and different from the outermost configuration of the other
elements. It is the cause of their similar chemical properties.
Practice Problem 4.16
Write the electronic configurations of N, P, As,
and Sb. State the feature that makes them have similar chemical properties.
We can use the periodic table to help us write electronic configurations of
the atoms of the elements. The periodic table can be divided into blocks
corresponding to the type of subshell occupied by the last electron added
(Figure 4.11). The two groups at the left of the periodic table—the alkali met-
als and the alkaline earth metals—constitute the
s
block because their last elec-
trons occupy
s
subshells. Hydrogen and helium also are in this block, and we
must mentally shift helium to a place beside hydrogen for this purpose. The six
periodic groups at the right of the table constitute the
p
block; their last elec-
trons go into
p
subshells. The transition metals belong to the
d
block, and the
f
block consists of the inner transition metals.
Note the similarity between the number of elements in a particular block
in each period and the maximum number of electrons permitted in the corre-
sponding type subshell:
We can use the periodic table
to help us write electronic
configurations of the atoms
of the elements.
Number of elements
Type of subshell
Maximum number of
in a particular block
or block
electrons in subshell
in each period
s
2
2
p
6
6
d
10
10
ChemSkill Builder
9.4, 9.5
f
14
14
After each noble gas, a new shell of electrons is started, as is a new period
of the periodic table. It turns out that electronic structure is the basis for the
periodic behavior of the elements.
The four transition metal series arise because, for each of these elements,
an electron has been added to the next-to-outermost shell. Addition of 10 elec-
trons to the 3
d
subshell
after the completion of the
4
s subshell
causes 10 ele-
ments to occur after calcium to be the first elements in their periodic groups.
The second, third, and fourth transition series occur because the 4
d
, 5
d
, and 6
d
subshells add electrons after the start of the fifth, sixth, and seventh shells,
The electronic structure of atoms
is the basis for the periodic
behavior of the elements.
