24. The d-block elements of the periodic table contains elements from group 3 to 12 and are
known as transition elements. In general, the electronic configuration of these elements is
(n-1)d -1°nsº-2. The d-orbitals of the penultimate energy level in their atoms receive
electrons giving rise to three rows of transition metals, i.e. 3d, 4d, 5d series. However zinc,
cadmium and mercury are not regarded as transition elements. Transition elements exhibit
certain characteristic properties like variable oxidation states, complex formation, formation
of coloured ions, etc. Transition metals are hard except zinc, cadmium and mercury.
a) Why zinc, cadmium and mercury are non-transition elements?
b) Why is Cu(II) ion coloured while Zn(II) ion is colourless in aqueous solution? c) Total number of
electrons in d and s orbitals in a transition element is 6. How are the electrons arranged in d and s
orbitals? (3)
Answers
Answer:
Explanation:
The d-block elements of the periodic table contains elements from group 3 to 12 and are
known as transition elements. In general, the electronic configuration of these elements is
(n-1)d -1°nsº-2. The d-orbitals of the penultimate energy level in their atoms receive
electrons giving rise to three rows of transition metals, i.e. 3d, 4d, 5d series. However zinc,
cadmium and mercury are not regarded as transition elements. Transition elements exhibit
certain characteristic properties like variable oxidation states, complex formation, formation
of coloured ions, etc. Transition metals are hard except zinc, cadmium and mercury.
a) Why zinc, cadmium and mercury are non-transition elements?
b) Why is Cu(II) ion coloured while Zn(II) ion is colourless in aqueous solution? c) Total number of
electrons in d and s orbitals in a transition element is 6. How are the electrons arranged in d and s
orbitals? (3)