TRANSITION METALS Flashcards
How do characteristics arise in transition metals
due to the incomplete d sublime within atoms and elements.
what is a ligand
A ligand is a molecule or ion that forms a coordinate bond with transition metal by donating a pair of electrons
what is a complex
central metal ion surrounded by ligands
what is the coordination number
number of coordinates bonds to the central metal atom or ion
what is a unidenteligand
form one coordinate bond per ligand
what is a bidente ligand
two atoms with lone pairs and can form two coordinate bonds per ligand
how is stability determined
substitution of mondenete ligand with a bidente or multi dente will lead to a more stable complex
how can a reaction be feasible
if Gibbs free energy is negative
why can transition metals become coloured ions
they are degenerate- contain the same energy- the d orbital will split into two energy levels in octahedral and tetrahedral complex, the colour will arise from electronic transitions from the ground state to the excited state between different d orbitals. A proton of visible light will be absorbed to promote d electrons to higher energy levels so that the light that is not absorbed is transmitted to give a colour.
how does colour change arise
change in oxidation state, coordination number and ligands, they alter energy split between the d orbitals changing the coordination number and altering the energy split between the d orbitals changing the frequency of light absorbed. The particular wavelengths of light will be absorbed so remains wavelengths are the colour perceived.
what are the physical properties of TM
dense metals, high melting and boiling point, hard and durable, high tensile strength, high electrical conductivity and malleable
variable oxidation state
all tm contain more than one oxidation state, the highest oxidation state is when they readily accept electron which make them powerful oxidising agents
catalytic activity
they are made catalyst by providing surface for reaction to take place and bind to reactants to form intermediates
heterogenous catalyst
spread onto a support medium to maximise their surface are and minimise costs
CONS of heterogenous catalyst
can become poisoned by impurities that block active sites and consequently have reduced efficiency these can be expensive to replace.
chemical properties of transition metals
coloured ions, complexes, variable oxidation state, catalytic activity
how are tm able to have variable oxidation states
they are able to donate and receive electrons and can oxidise and reduce because they have many electrons of similar energy in the valence- shell orbital
why is the acidity of [M(H2O)6]3+ is greater than [M(H2O)6]2+
metal ion swill become hydrated in water with ligands around central ions, major aqua ions will form coloured precipitate that they can identify metal ions with. their means when the ions is acidic, metal ions for 2+ ions which will be weaker compared to 3+. therefore the 3+ dissociate more and have greater attraction power to the OH ion, because they are stronger. with NaOH the solution of these metal will react as an acid with sodium hydroxide in a neutralisation reaction to form salt and water.
what does amphoteric mean
act as both acid and base
test tube reaction of OH ion
neutralisation reaction to form salt and water these reaction hydrolyse the metal ions to form coloured ions
test tube reaction of NH3 ion
form salt and ammonium ions, when ammonium is added in excess to these precipitate the copper salt undergoes ligand substitution to form deep blue solution
test tube reaction of 2+ ion of co32-
acids forming insoluble carbonates in water
test tube reaction of 3+ ion of CO32-
stronger acid meaning they react with sodium carbonate to form salt, water and carbon dioxide
test tube reaction of cl ion
ligand substitution to form tetrahedral ions with 4 cl- ligands, this occurs when they react with concentrated hydrochloric acid
