Outer electron configuration

Loss of one electron gives the noble gas configuration the very large difference between the first and second ionisation energies implies that an outer electronic configuration of a noble gas is indeed very stable. 

In this oxidation state the outer electronic configuration is 3d . so the compounds are necessarily paramagnetic (p. 229) and are coloured. 

With the outer electronic configuration 3d 4s vanadium can attain an oxidation state of -I- 5, but it shows all oxidation states between -I- 5 and -I- 2 in aqueous solution (cf titanium). 

In the older form of the periodic table, chromium was placed in Group VI, and there are some similarities to the chemistry of this group (Chapter 10). The outer electron configuration, 3d 4s. indicates the stability of the half-filled d level. 3d 4s being more stable than the expected 3d 4s for the free atom. Like vanadium and titanium, chromium can lose all its outer electrons, giving chromium)VI) however, the latter is strongly oxidising and is... 

Copper differs in its chemistry from the earlier members of the first transition series. The outer electronic configuration contains a completely-filled set of d-orbitals and. as expected, copper forms compounds where it has the oxidation state -)-l. losing the outer (4s) electron and retaining all the 3d electrons. However, like the transition metals preceding it, it also shows the oxidation state +2 oxidation states other than -l-l and - -2 are unimportant. 

Silver belongs to Group II (IB) of the Periodic Table. The metal has a outer electronic configuration. Silver has been shown to have three... 

Tellurium [13494-80-9] Te, at no. 52, at wt 127.61, is a member of the sixth main group. Group 16 (VIA) of the Periodic Table, located between selenium and polonium. Tellurium is in the fifth row of the Table, between antimony and iodine, and has an outer electron configuration of The four inner... 

It is possible to explain these trends in terms of the electron configurations of the corresponding atoms. Consider first the increase in radius observed as we move down the table, let us say among the alkali metals (Group 1). All these elements have a single s electron outside a filled level or filled p sublevel. Electrons in these inner levels are much closer to the nucleus than the outer s electron and hence effectively shield it from the positive charge of the nucleus. To a first approximation, each inner electron cancels the charge of one pro-... 

Outer electron configuration 2s22p3 3s23p3 2s22p4 Ss p 2s22p5 Ss p5 4s24p5 5s25p5... 

The reason usually cited for the great similarity in the properties of the lanthanides is that they have similar electronic configurations in the outermost 6s and 5d orbitals. This occurs because, at this point in the periodic table, the added electrons begin to enter 4f orbitals which are fairly deep inside the atom. These orbitals are screened quite well from the outside by outer electrons, so changing the number of 4/electrons has almost no effect on the chemical properties of the atom. The added electrons do not become valence electrons in a chemical sense—neither are they readily shared nor are they readily removed. 

ELEMENT z OUTER ELECTRON CONFIGURATION OXIDATION E° states M — - M+3 + 3e +3 ION RADIUS... 

In chemical education, the main motivation for basing chemistry on electronic configurations seems to be that if one knows the number of outer shell electrons in any particular atom, one can predict its chemical properties (Cotton and Wilkinson [1966], Kotz and Purcell [1987]). 

Figure 5. Niels Bohr came up with the idea that the energy of orbiting electrons would be in discrete amounts, or quanta. This enabled him to successfully describe the hydrogen atom, with its single electron, In developing the remainder of his first table of electron configurations, however, Bohr clearly relied on chemical properties, rather than quantum theory, to assign electrons to shells. In this segment of his configuration table, one can see that Bohr adjusted the number of electrons in nitrogen s inner shell in order to make the outer shell, or the reactive shell, reflect the element s known trivalency.

So what are we to make of the daim that the periodic table has now been explained in terms of electronic configurations and the number of outer-shell electrons possessed by atoms of the elements Perhaps the best way to answer this question is to admit that the explanation is approximate and that a number of objections can be raised to it. 

In addition to columns, rows and blocks of elements in the periodic table also have features of their electron configurations in common. Figure 5.1 highlights blocks of elements with the same outer orbitals. As you move from left to right in a row within a block, it shows which orbital is being filled. However, the elements in a row have a different number of electrons in their outer orbital. Consequently, adjacent elements in a row might have something... 

The shared electrons in the water molecule fill the outer energy shell of both hydrogen and oxygen. The electron configuration of the molecule, including the two shared electrons, is shown in Figure 7.1. 

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