- Electronic Configuration –
Electronic configuration of lanthanum and lanthanides are given below –
La(57) Lanthanum [Xe] 5d16s2
Ce(58) Cerium [Xe] 4f15d16s2
Pr(59) Praseodymium [Xe] 4f36s2
Nd(60) Neodymium [Xe] 4f46s2
Pm (61) Promethium [Xe] 4f56s2
Sm(62) Samarium [Xe] 4f66s2
Eu(63) Europium [Xe] 4f76s2
Gd(64) Gadolinium [Xe] 4f75d16s2
Tb(65) Terbium [Xe] 4f96s2
Dy(66) Dysprosium [Xe] 4f106s2
Ho(67) Holmium [Xe] 4f116s2
Er(68) Erbium [Xe] 4f126s2
Tm(69) Thulium [Xe] 4f136s2
Yb(70) Ytterbium [Xe] 4f146s2
Lu(71) Lutetium [Xe] 4f14 5d1 6s2
- Oxidation State –
The most common oxidation state of lanthanides is +3 which is obtained by removing two electrons from 6s and one electron from 4f. The +3 oxidation state of lanthanides is most stable due to the high energy difference between 4f and 6s; it is very difficult to remove more electrons from 4f-orbital. Some elements of this series exhibit +2 oxidation state e.g., – Sm, Eu, Tm, Yb, they have +2 oxidation state in aqueous solution, and some of the elements exhibit +4 oxidation state e.g., – Pr, Ce, Tb, and Dy.
This uneven distribution of oxidation state of lanthanides is due to the extra stability of empty, half filled or fully filled f-subshell because the stability of f-orbital affects the oxidation state of lanthanides.
- Eu (Europium) – atomic number 63, electronic configuration is [Xe]4f76s2 and Yb (Ytterbium) – atomic number 70, electronic configuration is [Xe]4f146s2.
They show +2 oxidation state by losing two electrons from 6s – subshell and attains extra stability by half-filled and fully- filled electronic configuration, 4f7 and 4f14 and readily converted into Eu+2 and Yb+2. Then, Eu+2 and Yb+2 changes into Eu+3 and Yb+3 which is the common oxidation state of lanthanides and acts as strong reducing agent.
- Ce (cerium) – atomic number 58, electronic configuration is [Xe]4f15d16s2 and Tb – atomic number 65, electronic configuration is [Xe]4f96s2.
They show +4 oxidation states by acquiring extra stability by noble gas and half-filled electronic configuration, f0 and f7. But they revert to common oxidation state +3 and acts as strong oxidizing agents.
Colour of lanthanides –
Lanthanides form colored compounds in their +3 oxidation state both in solid state as well as in solution form. Actually, the color of the compounds is depends on the number of unpaired electrons present in f-orbital. They have partially filled f-orbital resulting f-f transition is due to absorption in visible region. The lanthanides are in other oxidation state (+2 ans +4) and iso electronic with their counterparts will not form colored compounds.
Magnetic properties –
All lanthanides are paramagnetic except – Lu+3, Yb+3, Ce+4 due to unpaired electrons in the f-orbital. Magnetic moment can be calculated by –
μeff = (4S (S+1) + L(L+1))1/2
- 65Lanthanides are used as catalyst to speed up the chemical reactions. It is widely used in peteroleum or refining industry for conversion of crude oil into consumer products –gasoline, kerosene, heating oil etc. They are strong reducing agents. They are used in streetlights, searchlights, optical lenses. Lanthanides oxide are used…
- 62The f –block elements are those in which atoms or ions have valence electrons in f-orbital. They are also called inner transition elements because the last or valence electron enters in (n-2)f orbital means in anti-penultimate energy level. They are also referred as rare earth elements. The general electronic configuration…
- 60Electronic Configuration – Electronic configuration of lanthanum and Actinides are given below – Ac(89) Actinium [Rn] 6d17s2 Th(90) Thorium [Rn] 6d27s2 Pr(91) Proactinium [Rn] 5f26d16s2 U(92) Uranium [Rn] 5f36d16s2 Np(93) Neptunium [Rn] 5f46d16s2 Pu(94) Plutonium [Rn] 5f67s2 Am(95) Americium [Rn] 5f7 7s2 Cm(96) Curium [Rn]…
- 57Lanthanides are those elements in which 4f orbital is gradually filled from cerium (4f1) to lutetium (4f14) where the electrons are filled in (n-2)f orbital or penultimate shell (means second orbit below the outermost orbit). The lanthanide series contains consecutive 14 elements from atomic number 58 to 71, from cerium…
- 50In lanthanides series, first few elements are quite reactive with calcium but with increase in atomic number, their reactivity is quite similar to aluminum. Lanthanides when reacted with carbon in inert atmosphere, then there is the formation of carbides.On gentle heating, it combine with hydrogen. Lanthanides form halides in the…