Module 5: Transition metals Flashcards
Explain why transition elements are useful.
They have variable oxidation states so can donate or accept electrons easily. Transition elements are coloured depending on their oxidation state - useful in titrations as you can see the end point.
formation of coloured ions, *variable oxidation state
*catalytic activity. *Complex ion formation,
Typical properties of transition metals.
The existence of more than one oxidation state for each element in its compounds
For example iron commonly forms +2 and +3, chromium commonly forms +2,+3 and +6
see page 5 of this guide for more detail.
The formation of coloured ions
There are characteristic colours for each transition metal element and the colours can
vary in the different oxidation state. See the rest of the guide for many examples.
The catalytic behaviour of the elements and their compounds and their
importance in the manufacture of chemicals by industry
Iron is used as a catalyst in the Haber process to produce ammonia. Manganese dioxide
MnO2 catalyses the decomposition of hydrogen peroxide. Vanadium pentoxide V2O5
catalyses the contact process .
Transition metal characteristics of the elements …
Ti to Cu arise from an incomplete d sub-level in ions.
Transition metal electronic configurations. What is special about chromium and copper?
Sc - 1s22s22p63s23p6 4s23d1
Ti - 1s22s22p63s23p6 4s23d2
V - 1s22s22p63s23p6 4s23d3
Cr - 1s22s22p63s23p6 4s13d5
Mn - 1s22s22p63s23p6 4s23d5
Fe - 1s22s22p63s23p6 4s23d6
Co - 1s22s22p63s23p6 4s23d7
Ni - 1s22s22p63s23p6 4s23d8
Cu - 1s22s22p63s23p6 4s13d10
Zn - 1s22s22p63s23p6 4s23d10
A half filled d5 subshell and fully filled d10 subshell gives stability for chromium and copper.
Why is scandium and zinc not a transition metal?
When they lose electrons to form their specific ion, they either have a fully filled or empty d-subshell.
Sc3+ [Ar] 4s03d0
Zn 2+ [Ar] 4s03d10
Ti 3+ [Ar] 4s03d1
V3+ [Ar] 4s03d2
Cr 3+ [Ar] 4s03d3
Mn 2+ [Ar] 4s03d5
Fe 3+ [Ar] 4s03d5
Co 2+ [Ar] 4s03d7
Ni 2+ [Ar] 4s03d8
Cu 2+ [Ar] 4s03d9
Oxidation states and colours. (not sure whether to know)
Ti3+ purple
V2+ purple
V3+ green
V4+ blue
V5+ yellow
Cr2+ blue
Cr3+ green
Cr6+ orange
Mn2+ pink
Mn4+ maroon like
Mn6+ green
Mn7+ violet
Fe2+ grey
Fe3+ light yellow
Co2+ dark pink
Co3+ green
Ni2+ green
Cu2+ blue
Practical examples of catalytic behaviour?
Iron catalyst in Haber process.
MnO2 for decomposition of H2O2.
Cu2+ aqueous ions for reaction of Zn with acids.
