Transition Metals Flashcards
What are the characteristics of the metals from titanium and copper?
Good conductors of heat and electricity, hard, strong and shiny, have a high melting point and boiling point, fairly low chemical reactivity
What explains the overall similarity of these elements?
There are two outer 4s electrons and as you go across the period electrons are added to the inner 3d sub-shell
What elements divers from the pattern in electron arrangement?
Chromium and copper
Half full d levels makes the atoms…
…more stable
What is a transition metal?
It is one that forms at least one stable ion with a part full d-shell of electrons.
What elements are d-block elements but not transition metals? Why?
Zinc and scandium
Scandium only forms a Sc3+ (3d0) and zinc only firms Zn2+ (3d10)
What are the four common feature in transition metals
Variable oxidation state
Colour
Catalysis
Complex formation
What is it meant by variable oxidation state?
Transition metals have more than one oxidation state in their compounds.
They can therefore take part in many redox reactions
What does it mean for a transition metal to be a catalysts?
Catalyst affect the rate of reaction without being used up or chemically changed themselves.
What’s does it mean for a transition metal to partake in complex formation? How is a complex ion formed?
Transition metals form complex ions. A complex ion is formed when a transition metal is surrounded by ions or other molecules, called ligands
What type of bonds bond ligands to the transition metal?
By a co-ordinate bond.
What are the bonds formed when a transition metal accepts electron pairs from other ions or molecules
Co-ordinate DATIVE bonds
What is a ligand?
An ion or molecule with a lone pair of electrons that forms co-ordinate bond with transition metal.
What is a complex ion?
When 2, 4 or 6 ligands hind to a single transition metal.
Ions with coordination number 6 are normally…eg
Ions with coordination number 4 are normally…eg
… octahedral [Co(NH3)6]^3+
… tatrahedral [CoCl4]^2- or square planar [NiCN4]^2-
What is a complex?
A central metal atom or ion surrounded by ligands
This question is about aqua ions, if you dissolve the salt of a transition metal in water what happens?
The positively charged metal ion becomes surrounded by water molecules acting as ligands
What is the chelate effect?
It is when ligands are replaced that form more co-ordinate bonds. There is a significant increase in entropy, therefore delta G is very negative and the reaction is feasible.
Why are complexes coloured
The d orbitals do not have the same energy. Visible light is absorbed for electrons to be excited from lower to higher orbitals. Colour seen consists of colours not absorbed.
What are the factors that change colour and why
Identity of metal
Oxidation state of metal
Identity of ligands
Co-ordination number
If any of these change, size of the energy gap between the higher and lower d orbitals changes, so the frequency of light absorbed changes.
How to go from nanometres to meters
x10^-9
