Transition Metals Part 1 Flashcards
Transition metal
A metal that can form one or more stable ions with an incomplete d sub shell
Why are Sc and Zn d block elements
Because their outer electron is in a (3)d sub shell
Why are Sc and Zn not transition metals
They don’t form a stable ion with in incomplete d sub shell
What are the four characteristic properties of transition metals
Form coloured compounds
Variable oxidation state
Catalysts
Form complex ions
What do the characteristic properties of transition metals arise due to
Incomplete d sub shell
Complex ion
Central metal ion surrounded by ligands
Ligands
A molecule/ion that forms a coordinate bond with a transition metal by donating a pair of electrons
3 types of ligands
Monodentate, bidentate and multidentate
Monodentate ligands
Molecules/ions that can donate one electron pair to the central mental ion to form one coordinate bond
Bidentate ligands
Molecules/ions that can donate 2 electron pairs to the central metal ion to form 2 coordinate bonds
Multidentate ligands
Molecules or ions that can donate more than 2 electron pairs to the central mental ion to form more than 2 coordinate bonds
Coordination number
The number of coordinate bonds to the central metal atom/ion
What is coordination number not necessarily the same as
The number of ligands
When is coordination number the same as number of ligands
In monodentate ligands
What are the two common shapes of complex ions
Octahedral and tetrahedral
What 2 other shapes are also sometimes complex ions
Square planar and linear
Why do complexes containing water and/or ammonia ligands usually have an octahedral shape
Because they usually have a coordination number of 6
Why do complexes containing chloride ligands usually have a tetrahedral shape
They usually have a coordination number of 4
Why do complexes of copper and silver usually have a linear shape
They usually have a coordination number of two
What are ligand substitution reactions
Reaction where one ligand is replaced by another
Why does the coordination number and shape not chance when a ligand substitution reaction occurs between NH3 And H2O
They are similar in size
equation for aqueous cobalt salts reacting with excess ammonia (all 6 water ligands replaceed)
[Co(H2O)6]2+ +6NH3 >< [Co(nh3)6]2+ +6H2O
colouur change when aqueous cobalt II salts react with excess ammonia
pink to pale brown
equation for aqueous copper II salts reacting with excess ammonia (4 water ligands replaced)
[Cu(H2O)6]2+ + 4NH3 >< [Cu(H2O)2(NH3)4]2+ +4H2O
colour change when aqueous copper II salts are reacted with excess ammonia
pale blue to dark blue
coordination number and shape for aqueous copper II salts reacting with excess ammonia (4 water ligands replaced)
6-6
octabhedral- octahedral
why do reactions involving chloride ligands involve a change in coordination number AND SHAPE
chloride ligand larger than NH3 and H2O
equation aqueous cobalt II salts reacted with conc hcl (all 4 ligands replaced)
[Co(H2O)6]2+ + 4Cl- >< [CoCl4]2- + 6H2O
COLOUR, COORD NUMBER AND SHAPE aqueous cobalt II salts reacted with conc hcl (all 4 ligands replaced)
colour: pink-blue
coord no- 6 to 4
shape: octahedral to tetrahedrial
haemoglobin: coordination number of iron II in haem unit
4
haemoglobin: shape around iron II i haem unit
square planar
haemoglobin: what does planar haem unit bound to and what does it bind to in body
complex protein called globin
both water and oxygen can bind to iron II as ligands