3.4 Transition metals Flashcards
What is a transition metal?
A transition metal that has at least one ion with a partially filled d sub shell
Are Scandiam and Zinc transition metals?
No
Neither element forms an ion with a partially filled d sub shell
They are d block elements tho
Density
Properties of transition elements
- High
- More dense than other metals
- smaller atoms than other metals so able to pack closely together
Melting and boiling points
Properties of transition elements
- Higher melting and boiling points than other metals
- ions in metalic latice are small, bonding between the metal ions and delocalised eletrons is stronger
Reactivity
Properties of transition elements
- Moderate to low reativity
- Don’t react with cold water
- React with dilute acids
Why has transition metaks have a variaty of oxidation states?
Because of the close similarity in energy of the 4s and 3d electrons
Which element has the most oxidation states and why?
Mn
Because it has the most unpaired electrons in the d orbital
What is a ligand?
A molecule or ion that bonds to a metal ion by:
* forming a coordinate bond
* donating a lone pair of electrons
What is a complex ion?
A central metal ion surrounded by ligands
What is coordiantion number?
the total number of coordinate bonds form ligand to central transition metal ion of a complex ion
What shape is a ion with 6 coordinate complexes?
octahedral
What shape is a ion with 4 coordinate complexes?
tetrahedral
Name a small ligand that can form a octrahedral
- H2O
- NH3
Name a large ligand that forms a tetrahedral
Cl-
Colour of [Fe(H2O)6]2+
pale green
Colour of [Fe(H2O)6]3+
red-brown
Colour of [Cr(H2O)6]3+
ruby
Colour of [Cu(H2O)6]2+
blue
Colour of [Co(H2O)6]2+
pink
Why are transition element ions coloured?
When ligands bond to the central ion, the d orbitals move to 2 different energy levels. Gap between energy levels depends on:
* the ligand
* the coordination number
* the transition metal ion
result of the transfer of electrons bertween the orbitals of an unfilled
d sub shell
How can electorns be promoted from the lower 3d energy level?
Absorbtion of energy
Why is Colour of [Cu(H2O)6]2+ blue?
- red, yellow, green and purple regions of spectrum light energy absorbed
- blue light is reflected
What’s the colour change of [Ni(H2O)6]2+ to [Ni(NH3)6]2+
green to blue
What’s the colour change of [Co(H2O)6]2+ to [CoCl4]2-
pink to blue
Whats the colour of [CuCl4]2-
yellow
Whats the colour of [Cu(NH3)4(H2O)2]2+
deep blue
Name 2 different types catalysts
Heterogeneous and Homogenous catalysts
How can transision metals be used as catalysts?
using their partially full d orbitals for gain or loss of electron to change their oxidation states
Example of heterogenus catalysts
Harber process - Fe2O3 (s) catalyst N and H are (g)
Example of homogenus catalysts
Amalase breaking down starch
Biochem reactions
Test for amphoteric compound
Add NaOH dropwise untill ppt forms the add excess NaOH untill ppt disolves
Colour and equation
Cr3+ addition of NaOH dropwise
green ppt
Cr3+(aq) + 3OH-(aq) -> Cr(OH)3 (s)
Colour and equation
Fe2+ addition of NaOH dropwise
dark green ppt
Fe2+(aq) + 2OH-(aq) -> Fe(OH)2 (s)
Colour and equation
Fe3+ addition of NaOH dropwise
orange-brown ppt
Fe3+(aq) + 3OH-(aq) -> Fe(OH)3 (s)
Colour and equation
Zn2+ addition of NaOH dropwise
white ppt
Zn2+(aq) + 2OH-(aq) -> Zn(OH)2 (s)
Colour and equation
Cu2+ addition of NaOH dropwise
blue ppt
Cu2+(aq) + 2OH-(aq) -> Cu(OH)2 (s)
Colour, observation and equation
Cr3+ addition of NaOH in excess
ppt dissolves - green solution is observed
Cr(OH)3(s) + 3OH-(aq) -> [Cr(OH)6]3-(aq)
Colour, observation and equation
Fe2+ addition of NaOH in excess
No observable change
Not amphoteric
Colour, observation and equation
Fe3+ addition of NaOH in excess
No observable change
Not amphoteric
Colour, observation and equation
Zn2+ addition of NaOH in excess
ppt disolves and a colourless solution is observed
Zn(OH)2(s) + 2OH-(aq) -> [Zn(OH)4]2-(aq)
Colour, observation and equation
Cu2+ addition of NaOH in excess
No observable change
Not amphoteric
