Transition metal Flashcards
which block on the periodic table is mostly transition elements?
D block
what is a transition metal?
a transition metal is a metal that can form one or more stable ions with partially filled d sub-shell
how many electrons can a d subshell hold?
10
which two elements in d block are not transition metals?
Scandium and zinc
can you write the full electronic configuration of Cr?
[Ar] 3d5 4s1
which two elements have only one electron in 4s sub-shell
Cr and Cu
how many electrons does Cr have in its 3d sub-shell
5
how many elecrons does Cu have in its 3d sub-shell
10
how many elecrons does Cu have in its 4s sub-shell
1
why Sr and Zn aren’t transition metals?
their stable ions don’t have partially filled d-subshells.
what ion does Sr form? and how many elecrons are in their d subshell?
Sr3+, none
what ion does Zn form? and how many elecrons are in their d subshell?
2+, 10
can you write the full electronic configuration of Fe2+
[Ar] 3d6
which sub shell will lose electrons first when transition metals form ions?
4s sub shell
can you write the full electronic configuration of Cr3+
[Ar] 3d3
what are the physical properties of transition metals? (3)
- they all have a high density
- they all have a high melting and boiling points
- their ionic radii are more or less the same
what are their chemical properties? (4)
- they can form complex ions
- they from coloured ions
- they’re good catalysts
- they can exist in cariable oxidation states
how many ions can vanadium form? and what charges are they?
4, +2, +3, +4, +5
what is colour of V2+
violet
what is colour of V3+
green
what is colour of VO2+
blue
what is colour of VO2+
yellow
what is colour of Cr3+
green/violet
what is colour of Cr2O72-
orange
what is colour of Mn2+
pale pink
what is colour of MnO4-
purple
what is colour of Fe2+
pale green
what is colour of Fe3+
yellow
what is colour of Co2+
pink
what is colour of Ni2+
green
what is colour of Cu2+
blue
why transition elements have variable oxidation states?
because the energy levels of the 4s and 3d subshells are very close to one another. so different numbers of electrons can be gained or lost using fairly similar amounts of energy
what is a ligand?
A ligand is a species which can use its lone pair of electrons to form a dative covalent bond with a transition metal.
examples of ligands
H2O, NH3, Cl-, OH-, CN-,
what is the coordination number
The number of lone pairs of electrons which a cation can accept is known as the coordination number of the cation. It depends on the size and electronic configuration of that cation, and also on the size and charge of the ligand. 6 is the most common coordination number, although 4 and 2 are also known.
6-coordinate complexes are all __________.
octahedral
4-coordinate complexes are generally_______, and are formed with _______ ligands.
tetrahedral, larger
2-coordinate complexes are in general ________ , and are formed with _____ ions.
linear, Ag+
The rules covering the likely coordination number of transition metal complexes are:
a) Silver ions form linear complexes with a coordination number of 2;
b) Chloride ions and other large ions form tetrahedral complexes with a coordination number of 4;
c) Most other transition metal complexes are octahedral with a coordination number of 6.
A d-block element is an element which has at least one__________ and at least one _______ .
A d-block element is an element which has at least one s-electron and at least one d-electron.
In chromium the 4s1 3d5 structure is adopted because
the repulsion between two paired electrons in the 4s orbital is more than the energy difference between the 4s and 3d subshells. It is thus more stable to have unpaired electrons in the higher energy 3d orbital than paired electrons in the lower energy 4s orbital.
The oxidation state formed by an element in its compounds is determined by
the maximum number of electrons it can lose without requiring so much energy to remove the electrons that the energy cannot be recovered in bonding.
The oxidation states most commonly formed by the first-row d-block elements are as follows:
Sc: +3 only (d0) Ti: +3 (d1), +4 (d0) V: +2 (d3), +3 (d2), +4 (d1), +5 (d0) Cr: +3 (d3), +6 (d0) Mn: +2 (d5), +3 (d4), +4 (d3), +6 (d1), +7 (d0) Fe: +2 (d6), +3 (d5) Co: +2 (d7), +3 (d6) Ni: +2 (d8) Cu: +1 (d10), +2 (d9) Zn: +2 only (d10)
Cations which form complex ions must have two features:
- they must have a high charge density, and thus be able to attract electrons from ligands.
- they must have empty orbitals of low energy, so that they can accept the lone pair of electrons from the ligands.
