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For example, the electronic configuration of phosphorus (P) is 1s 2 2s 2 2p 6 3s 2 3p 3 so that there are 5 valence electrons (3s 2 3p 3), corresponding to a maximum valence for P of 5 as in the molecule PF 5; this configuration is normally abbreviated to [Ne] 3s 2 3p 3, where [Ne] signifies the core electrons whose configuration is identical ...
The lanthanide contraction, i.e. the reduction in size of the Ln 3+ ion from La 3+ (103 pm) to Lu 3+ (86.1 pm), is often explained by the poor shielding of the 5s and 5p electrons by the 4f electrons.
Among the lanthanides, lanthanum is exceptional as it has no 4f electrons as a single gas-phase atom. Thus it is only very weakly paramagnetic , unlike the strongly paramagnetic later lanthanides (with the exceptions of the last two, ytterbium and lutetium , where the 4f shell is completely full). [ 20 ]
In chemistry and atomic physics, an electron shell may be thought of as an orbit that electrons follow around an atom's nucleus.The closest shell to the nucleus is called the "1 shell" (also called the "K shell"), followed by the "2 shell" (or "L shell"), then the "3 shell" (or "M shell"), and so on further and further from the nucleus.
The second shell similarly contains a 2s orbital, and it also contains three dumbbell-shaped 2p orbitals, and can thus fill up to eight electrons (2×1 + 2×3 = 8). The third shell contains one 3s orbital, three 3p orbitals, and five 3d orbitals, and thus has a capacity of 2×1 + 2×3 + 2×5 = 18.
The p z orbital is the same as the p 0 orbital, but the p x and p y are formed by taking linear combinations of the p +1 and p −1 orbitals (which is why they are listed under the m = ±1 label). Also, the p +1 and p −1 are not the same shape as the p 0 , since they are pure spherical harmonics .
This effect is overwhelmed when the atom is positively ionised; thus Ce 2+ on its own has instead the regular configuration [Xe]4f 2, although in some solid solutions it may be [Xe]4f 1 5d 1. [11] Most lanthanides can use only three electrons as valence electrons, as afterwards the remaining 4f electrons are too strongly bound: cerium is an ...
For phosphorus (element 15) as an example, the concise form is [Ne] 3s 2 3p 3. Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms.