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56 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 6
Blocks of elements The periodic table is divided into blocks of
elements that correspond to the energy sublevel being filled as you
move across a period. The 1 and 2 groups constitute the s-block elements because their highest-energy electrons are in s orbitals. The
remaining groups of representative elements, 13 through 18, make
up the p-block of elements. In these elements, s orbitals are filled,
and the highest-energy electrons are in p orbitals.
The transition metals are the d-block elements. In these elements, the highest-energy electrons are in the d sublevel of the
energy level one less than the period number. Most d-block elements
have two electrons in s orbitals, but in some, such as chromium and
copper, the d sublevel “borrows” an electron from the s orbital to
form half-filled (Cr) or filled (Cu) d orbitals. The remaining block is
the f-block, or inner transition metals. The highest-energy electrons
in these elements are in an f sublevel of the energy level two less
than the period number.
The following Example Problem illustrates how electron configuration determines an element’s position in the periodic table.
Example Problem 6-1
Electron Configuration and the Periodic Table
The electron configuration of phosphorus is [Ne]3s 2 3p 3 . Without
using the periodic table, determine the group, period, and block in
which the element is located in the periodic table.
First, identify the valence electrons and note their energy level. In
phosphorus, the 3 in front of the s and p orbitals indicates that the
valence electrons are in the third energy level. Therefore, phosphorus will be found in the third period of the periodic table.
Next, note the sublevel of the highest-energy electrons. In the case
of phosphorus, these electrons are in a p sublevel. Therefore, phosphorus will be found in the p-block.
Finally, use the number of valence electrons to determine the group
number of the element. Phosphorus has two electrons in an s orbital
and three electrons in p orbitals for a total of five valence electrons.
Because there are no incomplete d or f sublevels, phosphorus must
be a representative element in group 15.
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56 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 6
Blocks of elements The periodic table is divided into blocks of
elements that correspond to the energy sublevel being filled as you
move across a period. The 1 and 2 groups constitute the s-block elements because their highest-energy electrons are in s orbitals. The
remaining groups of representative elements, 13 through 18, make
up the p-block of elements. In these elements, s orbitals are filled,
and the highest-energy electrons are in p orbitals.
The transition metals are the d-block elements. In these elements, the highest-energy electrons are in the d sublevel of the
energy level one less than the period number. Most d-block elements
have two electrons in s orbitals, but in some, such as chromium and
copper, the d sublevel “borrows” an electron from the s orbital to
form half-filled (Cr) or filled (Cu) d orbitals. The remaining block is
the f-block, or inner transition metals. The highest-energy electrons
in these elements are in an f sublevel of the energy level two less
than the period number.
The following Example Problem illustrates how electron configuration determines an element’s position in the periodic table.
Example Problem 6-1
Electron Configuration and the Periodic Table
The electron configuration of phosphorus is [Ne]3s 2 3p 3 . Without
using the periodic table, determine the group, period, and block in
which the element is located in the periodic table.
First, identify the valence electrons and note their energy level. In
phosphorus, the 3 in front of the s and p orbitals indicates that the
valence electrons are in the third energy level. Therefore, phosphorus will be found in the third period of the periodic table.
Next, note the sublevel of the highest-energy electrons. In the case
of phosphorus, these electrons are in a p sublevel. Therefore, phosphorus will be found in the p-block.
Finally, use the number of valence electrons to determine the group
number of the element. Phosphorus has two electrons in an s orbital
and three electrons in p orbitals for a total of five valence electrons.
Because there are no incomplete d or f sublevels, phosphorus must
be a representative element in group 15.
▲