transition metals Flashcards
[Cu(H2O)6]2+
from CuSO4.5H2O)(s)
pale blue
Cu(OH)2(s)
NH3 drop wise to Cu2+(aq)
pale blue precipitate
[Cu(NH3)4(H2O)2]2+
excess NH3 to Cu2+
dark blue
(CuCl4)2-
excess HCl to Cu2+(aq)
yellow
Cu+
reduction of Cu2+ which I-
white precipitate (CuI) and brown I2
Cu2+/Cu
Disproportion of Cu+
brown solid (Cu) and blue solution (CuSO4)
(CoCl4)2-
from CoCl2.6H2O(s) plus water and excess Hal
blue
[Cr(H2O)6]3+
from KCr(SO4)2.12H2O(s)
Pale purple (heat goes to green)
due to impurities common for Cr(III) to appear green in solution
Cr(OH)3(s)
NH3 dropwise to Cr3+(aq)
dark green precipitate
[Cr(NH3)6]3+
excess NH3 to Cr2+(aq)
purple
[Cr(OH)6]3-
excess OH- to Cr(OH)3(s)
dark green
(Cr2O7)2-
from K2Cr2O7(s) in 0.1mol dm-3 H2SO4 orange
(CrO4)2–
oxidation of Cr3+ with hot alkaline H2O2 yellow
[Mn(H2O)6]2+
from MnSO4.4H2O(s)
pale pink
Mn(OH)2(s)
NaOH dropwise to Mn2+(aq)
pale brown precipitate
[Fe(H2O)6]2+
from FeSO4.7H2O(s)
pale green
Fe(OH)2(s)
NaOH dropwise to Fe2+(aq)
dark green precipitate
[Fe(H2O)6]3+
from FeCl3.6H2O(s)
yellow
Fe(OH)3(s)
NaOH dropwise to Fe3+(aq)
orange-brown precipitate
MnO4–/Fe2+ to Mn2+/Fe3+
purple (MnO4–) to pale pink (Mn2+) (in titrations, so dilute that it is practically colourless)
I–/Fe3+ to I2/Fe2+
orange brown (Fe3+) to brown (I2)
define a transition element
a d block element that forms at least one stable ion with a partially filled d subshell
where are the transition elements located in the periodic table
middle block from Ti to Cu
2 elements in d block not considered transition elements
scandium and zinc
-scandium only forms Sc3+ ions where d block is empty
- zinc only forms Zn2+ where d orbital is full
physical properties of transition elements
- metallic
- high density
- high melting and boiling point
- shiny
- good conductors of heat and electricity
what are the chemical properties of transition metals
-coloured compounds/ions in solution
- good catalysts
- form complex ions
-variable oxidation states (take part in many redox reactions)
2 main ways in which transition metals act as good catalysts
- provide a surface on which a reaction can take place
- they change oxidation states to form intermediates required for pathways with lower activation energies
What is a complex ion
transition metal ion bonded to one or more ligands by coordinate bonds
define a ligand
molecule or ion that can donate a pair of electrons to the metal to form a coordinate bond
What is a coordinate bond
a bond in which one atom requires both the electrons required for bonding, also known as dative bonding
what does coordinate number indicate
number of coordinate bonds formed between the metal ion and its ligands
what is a mono/Unidentate ligand
What is a bidentate ligand
-a ligand that forms one(mono)/2(bi) coordinate bond to the central metal ion
common monodentate ligands
Cl-,NH3,H2O,CN-
what is optical isomerism
non-superimposable mirror images
What is cis-plain used for
it is used as an anti-cancer drug
it binds to DNA or fast growing cancer cells and prevents cell division, hence reducing the growth of cancer
why is CO toxic
CO coordinately bonds to Fe2+ and bonds more strongly to Fe2+ than O2. so stops O2 from bonding to haemoglobin, so O2 cannot be transported around the body
