Download 13.2: First Row D

13.2: First Row D-Block Elements
Ch. 3 in online alternative text
4th Period Transition Elements (Sc)(Zn)
•
•
Definition
– An element that possesses an incomplete “d” sublevel in one or more of its
oxidation states
Exceptions
– Scandium is not a typical transition element as Sc3+ has no d electrons
– Zn is not a transition metal as it has does not lose any d electrons in any of its
transition states (therefore it’s d level is always complete!).
Electron Configurations ScZn
•
•
•
•
•
•
•
•
•
•
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
1s22s22p63s23p64s23d1
1s22s22p63s23p64s23d2
1s22s22p63s23p64s23d3
1s22s22p63s23p64s13d5
1s22s22p63s23p64s23d5
1s22s22p63s23p64s23d6
1s22s22p63s23p64s23d7
1s22s22p63s23p64s23d8
1s22s22p63s23p64s13d10
1s22s22p63s23p64s23d10
For Cr and Cu it is more
energetically favorable to
half-fill and completely fill
the d sublevel, so they only
have 1 4s electron.
This is referred to as the
“special stability of full and
half full sublevels. “
Characteristic Properties of Transition Elements
• Variable Oxidation States
Mn 2+
Mn 3+
Mn 4+
Mn 7+
• Formation of Complex Ions
• Colored Complexes
• Catalytic Behavior
3d and 4s sublevels are very similar in
energy.
Transition metals lose 4s electrons first
when they are becoming ions.
Variable Oxidation States
• All transition metals show an oxidation state of 2+.
• As move to the right: less and less likely to lose 3d
electrons
Ionization Energies
• Group 1 or 2 metals: 1st ionization energies
lower than transition metals.
– Sudden increase in successive ionization energies
• Transition metals = 1st ionization energies
higher
– No sudden increase in successive ionization
energies
• Because 3d and 4s electrons have similar energies
– Oxidation state depends on environment
(oxidizing (agent) strength of surrounding species)
Formation of Complex Ions
• Ligands
– Neutral molecules or anions that contain a non-bonding pair of
electrons
– “Electron rich”
– Highly attracted to transition metal ions
• Because transition metals contain unfilled d-orbitals
– Common ligands
•
•
•
•
Water
Ammonia
Chlorine
Cyanide
Formation of Complex Ions (cont’d)
• Ligands form co-ordinate covalent bonds with
transition metal ions
– A co-ordinate bond (also called a dative covalent
bond) is a covalent bond (a shared pair of electrons)
in which both electrons come from the same atom.
• Coordination number
– number of lone pairs bonded to the metal atom
What is the coordination number of these ligands?
Formation of Complex Ions
Formation of Colored Complexes
• Five D orbitals
– In free ions, the five D orbitals are degenerate (have the same energy)
– In complex ions, the orbitals are split into 2 distinct energy levels
– The energy difference between the two split levels corresponds to a
particular wavelength and frequency in the visible spectrum
– When light falls on the complex ion solution, energy of that particular
wavelength/frequency is absorbed and electrons get excited.
– The color of the complex ion solution is complementary to the color of the
light waves that have been absorbed.
The diagram shows the arrangement of the d
electrons in a Cu2+ ion before and after six
water molecules bond with it.
Formation of Colored Complexes
• The amount of split between the d orbitals
depends on…
– Transition metal
– Oxidation state (1+, 2+, 3+….)
– Shape of the complex (octahedral, square planar,
linear…)
– Nature of the ligand (water, ammonia, fluoride, etc….)
• If the d orbital is completely full (Zn2+ ,Sc3+ , Cu1+ ),
no splitting occurs and the complex is colorless.
Bookwork
• Alternative Text Ch. 3
– Pg. 95
– # 1, 2, 3, 6,