3.4 chemistry of the d-block transition metals Flashcards
elements of the d-block have their outer electrons in the __ orbitals?
d orbitals
are all d-block elements transition metals?
no
what is a transition metal?
- a d-block element that forms one or more stable ions with partially filled d-orbitals
although zinc is part of the d-block, why is it not a transition element?
because it doesnt have a partially filled d sub-shell as an atom or in its stable ion Zn2+
what are some transition metal characteristics?
- variable oxidation states
- form complex ions
- form coloured ions in solution
- catalyse reactions either as elements or in compounds
what are the two exceptions to the electronic configuration rule that the 4s orbitals are filled before the 3d orbitals?
- chromium
- copper
Cr : [Ar] 3d^5 4s^1
Cu : [Ar] 3d^10 4s^1
when transition metal atoms form ions, what electrons are lost first?
the 4s electrons are lost first
when you write or draw the electronic configuration of any transition metal ion, they always have an empty 4s orbital
write the electronic configuration for Ni^2+
Ni : [Ar] 3d^8 4s^2
Ni^2+ : [Ar] 3d^8
write the electronic configuration for Fe^3+
Fe : [Ar] 3d^6 4s^2
Fe^3+ : [Ar] 3d^5
can transition metals have different oxidation states?
yes
why can transition metas have different oxidation states?
- because the electrons in the 4s and 3d orbitals have very similar energies
- so the energy required to remove/gain any of these electrons is similar
(a relatively similar amount of energy is required to gain or lose different number of electrons)
- the lower oxidation states are found as simple ions e.g Co^2+ or Fe^3+
- the higher oxidation states only exist when the metals are covalently bonded to very electronegative elements such as oxygen e.g CrO4 2- or MnO4 -
what is the most common oxidation states of chromium?
+2, +3 and +6
what is the most common oxidation states of manganese?
+2, +4 and +7
what is the most common oxidation states of iron?
+2 and +3
what is the most common oxidation states of cobalt?
+2 and +3
what is the most common oxidation states of copper?
+1 and +2
what does a transition metal complex consist of?
- a central metal ion surrounded by a number of molecules or ions called ligands
ligand definition
- a small molecule or ion with a lone pair of electrons that coordinate bonds to a central metal atom to form a complex ion
(lone pair donor)
the ligands are attached to the central ion by what?
coordinate bonds
the ligand supplies the two electrons which is what makes it a coordinate bond
when do ligands form coordinate bonds?
(transition metal ions have many orbitals available for bonding, many of which are empty)
- when an orbital, from the ligand, containing a lone pair of electrons overlaps with empty orbitals on the transition metal ion
how are ligands classified?
by the number of coordinate bonds that they can form in complexes