1. Zinc and Scandium are not transition elements!
Transition elements are d block elements that have an ion with an incomplete d subshell.
Element
Electronic Configuration 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
Zinc and Scandium are not transition elements!
Scandium forms only one ion, Sc3+. In forming this ion, scandium loses the two electrons in the 4s subshell and the one electron in the 3d subshell. This leaves the ion with no d subshell – it therefore isn’t a transition metal.
Zinc forms only one ion, Zn2+. In forming this ion, zinc loses the two electrons in the 4s subshell. This leaves the ion with a complete d subshell – it therefore isn’t a transition metal.
Note that chromium and copper don’t fit the pattern. They fill their 3d subshell before their 4s subshell.

2. Transition Metals have variable Oxidation States
Fe3+ + e Fe2+
Pale green  Yellow
Oxidation States of Manganese +2
in Mn2+ +3
in Mn2O3 +4
in MnO2 +6
in MnO42- +7
in MnO4-
Cr2O H+ + 6e Cr3+ + 7H2O
Orange  Green
MnO H+ + 5e Mn2+ + 4H2O
Purple  Pale Pink
Precipitation reactions of Transition Metals
Catalytic Activity
Metal Ion & Colour
Precipitate
Cu2+ - Blue Solution
Cu(OH)2 -Blue
Co2+ - Pink Solution
Co(OH)2 -Blue
Fe2+- Pale Green Solution
Fe(OH)2 - Green
Fe3+ - Yellow Solution
Fe(OH) Brown
Iron in the Haber Process: combines hydrogen and nitrogen to make ammonia
Nickel in the hydrogenation of C=C bonds: manufacture of margarine from vegetable oils.
Vanadium(V) oxide in the Contact Process: reaction which converts sulphur dioxide into sulphur trioxide. Sulphur dioxide gas is passed together with air (as a source of oxygen) over a solid vanadium(V) oxide catalyst.
Manganese (IV) Oxide in the decomposition of hydrogen peroxide
N2 + 3H2  2NH3
CH2= CH2 + H2 CH3CH3
3. 2SO2 + O2  2SO3
4. H2O2  H2O + ½ O2