DM - Inorganic chemistry and the periodic table *01 Flashcards
where are transition metals found in the periodic table?
d-Block
what is a transition metal?
a d-Block element that can form at least one stable ion with an incomplete d sub-shell
why isn’t scandium a transition metal?
only forms one ion Sc3+
this has an empty d sub-shell
electronic config. [Ar]3d14s2 so when it loses 3 e- has electronic config. [Ar]
why isn’t zinc a transition metal?
only forms one ion, Zn2+
this has a full d sub-shell
electron config. = [Ar]3d104s2
when it form Zn2+ it loses 2 e- (both form 4s sub-shell) so it keeps its full 3d sub-shell
which sub-shell to transition metals lose electrons from 1st to form ions?
4s sub-shell
transition metals - special chemical properties
- variable oxidation states
2. form coloured ions in solution
transition metals - iron properties
oxidation states =
+2 and +3
coloured precipitate =
Fe2+ - green
Fe3+ - orange
coloured aq =
Fe2+ - green
Fe3+ - yellow
transition metals - copper properties
oxidation states =
+1 and +2
coloured precipitate =
Cu2+ - pale blue
colour in aq =
Cu2+ - blue
what is a complex ion?
a complex (or complex ion) is a central metal atom or ion surrounded by coordinately bonded ligands
what is a ligand?
an atom, ion or molecule that donates a pair of electrons to a central transition metal ion to form a coordinate (dative) bond.
what is ligand substitution?
one ligand can be swapped for another - usually causes a colour change.
how do ligands form bonds?
using lone pairs of electrons
they donate a pair of electrons to a central transition metal ion to form a coordinate (dative) bond
what is a mono/unidentate ligand?
ligands with one lone pair of electrons
what is a bidentate ligand?
ligands with two lone pairs of electrons
what is a polydentate ligand?
ligands with more than two lone pairs of electrons
ligand substitution reactions - what happens when ligands similar size?
the coordination number does change and neither does the shape
colour does change
eg. H2O, NH3 or CN-
for example
[Cr9(H2O)6]3+ + 6NH3 [Cr(NH3)6]3+ + 6H2O
octrahedral octrahedral
dark green purple
ligand substitution reactions - what happens when ligands different sizes?
change in coordination number and shape and colour
eg. H2O and Cl-
for example:
[Cu9H2O)6]2+ + 4Cl- [CuCl4]2- + 6H2O
octrahedral pale blue —-> tetrahedral yellow
ligands substitution reactions - why + what happens when substitution only partial?
happens when you add excess ammonia
for example:
[Cu(H2O)6]2+ + 4NH3 [Cu(NH3)4(H2O)2]2+ + 4H2O
octrahedreal in excess octrahedral
pale blue dark blue
what happens to transitions metals when react with sodium hydroxide?
form brightly coloured precipitates
copper 2+ does this with - NH3 - too