F325 - Transition Elements Flashcards
Which two elements do not fill their subshells according to the conventional structure? Why?
Cr - 4s1 3d5 - to have one electron in each of the d subshells
Cu - 4s1 3d10 - to have full d subshells
What is a transition element?
An element that forms at least one ion with a partly filled d subshell.
What are the main properties of transition elements and their compounds?
- variable oxidation states
- used as catalysts
- form coloured compounds
- form precipitates on addition of sodium hydroxide
What is the colour change in the formation of the copper(II) hydroxide precipitate?
Blue solution to Pale blue precipitate
What is the colour change in the formation of the iron(II) hydroxide precipitate?
Green solution to Green precipitate
What is the colour change in the formation of the iron(III) hydroxide precipitate?
Yellow solution to Rust precipitate
What is the colour change in the formation of the cobalt(II) hydroxide precipitate?
Pink solution to blue-green precipitate
What is a ligand?
A species that can use one or more lone-pairs to form dative covalent bonds to a transition metal ion, forming a complex.
What is a complex ion?
A transition metal ion bonded to one or more electron-donating species (ligands) by dative covalent bonds from the ligands to the metal.
What is the coordination number?
The number of dative bonds formed between the ligands and a central transition metal ion in a complex.
What shape and bond angles would a complex with a coordination number of six have?
Octahedral
90
What shape and bond angles would a complex with a coordination number of four have?
Tetrahedral, 109.5
Or
Square planar, 90
What does the term bidentate ligand mean?
A ligand that has two lone-pairs of electrons which can form two separate dative covalent bonds to a transition metal ion.
What are the two types of stereoisomerism shown by complexes?
- cis-trans isomerism
- optical isomerism
In an octahedral complex what are the bond angles between the two ligands to show the cis- isomer and to show the trans- isomer?
Cis - 90
Trans - 180
Besides octahedral what other shape of complex can show cis-trans isomerism?
Square planar
How is cis-platin used as an anti-cancer drug?
- cis-platin binds to the DNA in a cell
- it binds the two strands of DNA together so that the cell is unable to copy it’s DNA
- this makes the cell incapable of dividing and causes it to die
- it does this more effectively in fast-growing cells than trans-isomer
What is meant by the term optical isomerism?
Molecules that are non-superimposable mirror images of each other. The two isomers (enantiomers) rotate the plane polarised light in opposite directions.
What shape of complex shows optical isomerism?
Octahedral
What is the colour change associated with the ligand substitution of aqueous copper(II) sulphate on the addition of concentrated hydrochloric acid?
Light blue solution to yellow solution
What is the colour change associated with the ligand substitution of aqueous copper(II) sulphate on the addition of concentrated ammonia?
Blue solution to a (light blue precipitate followed by a) dark blue solution
What is the colour change associated with the ligand substitution of aqueous cobalt(II) chloride on the addition of concentrated chloride ions?
Pink solution to a blue solution
