Periodic Relationships (8.1.5) Flashcards
• The periodic table is arranged with columns of elements having similar valence electron configurations.
• The periodic table is arranged with columns of elements having similar valence electron configurations.
• Noble gas electron configurations are very stable.
• Noble gas electron configurations are very stable.
• Groups on the periodic table tend to react to gain or lose electrons to match a noble gas electron configuration.
• Groups on the periodic table tend to react to gain or lose electrons to match a noble gas electron configuration.
Valence electrons are electrons in orbitals beyond
the previous noble gas core. These electrons
determine the bonding characteristics of an
element.
The periodic table is arranged with columns of
elements having similar valence electron
configurations. The columns are referred to as
groups.
For example, the alkali metals (group 1) all have
one valence electron in an s orbital.
Noble gas electron configurations are very stable.
This stability is because any electrons added to a
noble gas have to go into the next highest energy
level. For example, the next available orbital after
the neon electron configuration (1s2
2s2
2p6
) is the 3s
orbital. However, since every electron is paired, a
relatively large amount of energy must be put in to
remove an electron.
Valence electrons are electrons in orbitals beyond
the previous noble gas core. These electrons
determine the bonding characteristics of an
element.
The periodic table is arranged with columns of
elements having similar valence electron
configurations. The columns are referred to as
groups.
For example, the alkali metals (group 1) all have
one valence electron in an s orbital.
Noble gas electron configurations are very stable.
This stability is because any electrons added to a
noble gas have to go into the next highest energy
level. For example, the next available orbital after
the neon electron configuration (1s2
2s2
2p6
) is the 3s
orbital. However, since every electron is paired, a
relatively large amount of energy must be put in to
remove an electron.
Due to electron shielding, the energies of the 4f
orbitals, the 6s orbital, and the 5d orbitals are all
approximately equal. Likewise, the energies of the
5f orbitals, the 7s orbital, and the 6d orbitals are all
approximately equal. Because of this equivalence,
the order in which orbitals fill is not immediately
obvious.
However, the periodic table is arranged in such a
way that the order that orbitals fill is reasonably
clear. The lanthanide series can be thought of as
occupying the space on the periodic table between
the elements filling the 6s orbital and the elements
filling the 5d orbitals. Therefore, the 4f orbitals
generally fill after the 6s orbital and before the 5d
orbitals. Likewise, the actinide series can be
thought of as occupying the space on the periodic
table between the elements filling the 7s orbital and
the elements filling the 6d orbitals. Therefore, the 5f
orbitals generally fill after the 7s orbital and before
the 6d orbitals.
However, there are exceptions to the rule. For
example, the electron configuration of thorium (Th)
is [Rn]6d2
7s2
, while the electron configuration of
protactinium (Pa) is [Rn]5f2
6d1
7s2
.
Groups on the periodic table tend to react to gain or
lose electrons to match a noble gas electron
configuration.
Alkali metals (group 1) such as potassium have one
more valence electron than the previous noble gas
core. Therefore, alkali metals tend to react to lose
one electron, forming a +1 oxidation state which is
isoelectronic with the previous noble gas.
Alkaline earth metals (group 2) such as calcium
have two more valence electrons than the previous
noble gas core. Therefore, alkaline earth metals
tend to react to lose two electrons.
Halogens (group 17) such as chlorine have one
less valence electron than the next noble gas core.
Therefore, halogens tend to react to gain one
electron.
Chalcogens (group 16) such as oxygen have two
less valence electrons than the next noble gas core.
Therefore, chalcogens tend to react to gain two
electrons.
Due to electron shielding, the energies of the 4f
orbitals, the 6s orbital, and the 5d orbitals are all
approximately equal. Likewise, the energies of the
5f orbitals, the 7s orbital, and the 6d orbitals are all
approximately equal. Because of this equivalence,
the order in which orbitals fill is not immediately
obvious.
However, the periodic table is arranged in such a
way that the order that orbitals fill is reasonably
clear. The lanthanide series can be thought of as
occupying the space on the periodic table between
the elements filling the 6s orbital and the elements
filling the 5d orbitals. Therefore, the 4f orbitals
generally fill after the 6s orbital and before the 5d
orbitals. Likewise, the actinide series can be
thought of as occupying the space on the periodic
table between the elements filling the 7s orbital and
the elements filling the 6d orbitals. Therefore, the 5f
orbitals generally fill after the 7s orbital and before
the 6d orbitals.
However, there are exceptions to the rule. For
example, the electron configuration of thorium (Th)
is [Rn]6d2
7s2
, while the electron configuration of
protactinium (Pa) is [Rn]5f2
6d1
7s2
.
Groups on the periodic table tend to react to gain or
lose electrons to match a noble gas electron
configuration.
Alkali metals (group 1) such as potassium have one
more valence electron than the previous noble gas
core. Therefore, alkali metals tend to react to lose
one electron, forming a +1 oxidation state which is
isoelectronic with the previous noble gas.
Alkaline earth metals (group 2) such as calcium
have two more valence electrons than the previous
noble gas core. Therefore, alkaline earth metals
tend to react to lose two electrons.
Halogens (group 17) such as chlorine have one
less valence electron than the next noble gas core.
Therefore, halogens tend to react to gain one
electron.
Chalcogens (group 16) such as oxygen have two
less valence electrons than the next noble gas core.
Therefore, chalcogens tend to react to gain two
electrons.
Elements with partially-filled 4f orbitals are part of which of the following?
The lanthanide series (B)
The lanthanide series have partially-filled 4f orbitals. They are named after the first element in the series, lanthanum. The lanthanide and actinide series comprise the f block of the periodic table.
What is the general order of filling of the 4f, 5d, and 6s orbitals?
6s, 4f, 5d (D)
This is generally correct. The periodic table can be used to help see this relationship, as long as it is remembered that the lanthanides “stack” between barium and hafnium.
Tellurium is located in which block on the periodic table?
p block (B)
Which of the following characteristics is most alike in elements that have similar chemical properties?
Valence electron configuration (C)
Which of the following best defines isoelectronic?
having the same number of electrons (C)
Which group does selenium belong to?
chalcogens (C)
Which species in the following series is not isoelectronic with others?
Cl −, Ca2+, Ar, K, P3−
K (C)
What family does rubidium belong to?
alkali metals (A)
Rubidium is a metal in group 1 on the periodic table.
How many electrons must chalcogens gain / lose to achieve a noble gas configuration?
gain two (A)
Chalcogens are in group 16; gaining two electrons would bring them to a noble gas configuration with eight electrons in their valence shell. Oxygen and sulfur are chalcogens.
What is the most common oxidation state for alkaline earth metals?
+2 (A)
Alkaline earth metals tend to lose two electrons to match the nearest noble gas configuration.
