Hydrogen subshells

These are shown in Fig. 2.3 and illustrate most convincingly the various quantum shells and subshells described in the preceding section. The energy required to remove the I electron from an atom of hydrogen is 13.606 eV (i.e. 1312 kJ per mole of H atoms). This rises to 2372 kJ mol for He (Is-) since the positive charge on the helium nucleus is twice that of the... 

The hierarchy of shells, subshells, and orbitals is summarized in Fig. 1.30 and Table 1.3. Each possible combination of the three quantum numbers specifies an individual orbital. For example, an electron in the ground state of a hydrogen atom has the specification n = 1, / = 0, nij = 0. Because 1=0, the ground-state wavefunction is an example of an s-orbital and is denoted Is. Each... 

An effective way to determine the detailed electron configuration of any element is to use the periodic table to determine which subshell to fill next. Each s subshell holds a maximum of 2 electrons each p subshell holds a maximum of 6 electrons each d subshell holds a maximum of 10 electrons and each / subshell holds a maximum of 14 electrons (Table 17-5). These numbers match the numbers of elements in a given period in the various blocks. To get the electron configuration, start at hydrogen (atomic number = 1) and continue in order of atomic number, using the periodic table of Fig. 17-10. 

With the exception of hydrogen, the subshells within each shell have slightly different energies the s subshell has the lowest energy, then p, then d, and so on. The table shows the different subshells present in each shell. Each type of subshell contains one or more orbitals. 

The difference in energy between subshells in multielectron atoms results from electron-electron repulsions. In hydrogen, the only electrical interaction is the attraction of the positive nucleus for the negative electron, but in multielectron atoms there are many different interactions to consider. Not only are there the attractions of the nucleus for each electron, there are also the repulsions between every electron and each of its neighboring electrons. 

Hydrogen atoms inserted in TbFe6Co5Ti crystal lattice orient quadrupolar moment of the electronic 4f-subshell in an electric field created by a neighbouring ions and electrons along c-axis, that caused to orient of magnetic moment of Tb ion along basal plane. It is well known [4,10], that for the rare-earth ions with Stevens coefficient aj > 0 (Sm, Er, Yb) the magnetic moment is parallel, while for... 

The first four levels of orbitals in the hydrogen atom are listed with their quantum numbers in Table 12.3. Note that each set of orbitals with a given value of (sometimes called a subshell) is designated by giving the value of... 

We have seen that the term symbol for the ground state of the hydrogen atom is -5i/i. For a helium atom t = 0, 5 = 0. J = 0, and the term symbol for the ground state is 5 . For an atom such as boron, we can make use of the fact that all closed shells and subshells (such as the He example just given) contribute nothing to the term symbol. Hence both the Is- and 2jZ electrons give L = S = J = 0. The 2p electron has L = I, 5 = J. and J = 1 i, yielding -Pyz carbon there are two p electrons. 

The pairing of electrons is important, because it confers a degree of stability on the species concerned. Electrons in an atom are contained within atomic orbitals, each of which may only hold a maximum of two electrons. The electron in a hydrogen atom is contained in the first principal quantum shell, which is indicated by 1. Within this principal quantum shell, there is only one type of subshell, and this is represented by the letter s . The electronic configuration of hydrogen may be written as Is1. The raised postscript indicates that there is only one electron in that particular orbital. 

As each orbital may contain a maximum of two electrons, the helium atom has a full complement at Is2, as does the hydrogen anion. There is only one subshell in the first principal quantum level, and so there can only be two elements that have electrons only in this level. That is why there are only two first row elements of the Periodic Table. 

It is important to note that 7s(p = 0.001) is invariably larger than e, for the highest occupied orbital (except for the special case of hydrogen). This is due to the contributions of lower orbitals, which do have some electronic density at the p(r) = 0.001 au surface. This shows that7s(p = 0.001) inherently takes interpenetration of subshells into account. 

---