Shell outermost

In any group of the periodic table we have already noted that the number of electrons in the outermost shell is the same for each element and the ionisation energy falls as the group is descended. This immediately predicts two likely properties of the elements in a group (a) their general similarity and (b) the trend towards metallic behaviour as the group is descended. We shall see that these predicted properties are borne out when we study the individual groups. 

Arsenic is the third member of the nitrogen family of elements and hence possesses an outermost shell having the electron configuration of 4 The... 

Primary bond formation takes place by various interactions between electrons in the outermost shell of two atoms resulting in the production of a more stable... 

An ionic bond is formed by the donation of an electron by one atom to another so that in each there is a stable number of electrons in the outermost shell (eight in the case of most atoms). An example is the reaction of sodium and chlorine Figure 5.1). 

The changes in energy responsible for the formation of bonds occur when the valence electrons of atoms, the electrons in the outermost shells, move to new locations. Therefore, bond formation depends on the electronic structures of atoms discussed in Chapter 1. 

Throughout we have considered only the portion of the mole refraction produced in the outermost shell. In the case of xenon one finds by our methods that as much as 4 per cent, of the total mole refraction is due to the N shell accordingly our values of SK for the 0 electrons would be decreased by about 0-1 on making this correction. The values of R for ions would in most cases not be changed materially by the explicit consideration of the polarisation of inner shells, and so the less complicated treatment of this paper has been adopted. 

Action process - a representation of an unfolding action and event processes of change and transitoiy spatial arrangement (e.g. a diagram showing how a sodium atom becomes a sodium atom through the loss of the outermost shell electron). 

A formal charge is a charge associated with an atom that does not exhibit the expected number of valence electrons. When calculating the formal charge on an atom, we first need to know the number of valence electrons the atom is supposed to have. We can get this number by inspecting the periodic table, since each column of the periodic table indicates the number of expected valence electrons (valence electrons are the electrons in the valence shell, or the outermost shell of electrons— you probably remember this from high school chemistry). For example, carbon is in Column 4A, and therefore has four valence electrons. Now you know how to determine how many electrons the atom is supposed to have. 

Now that we know how to determine hybridization states, we need to know the geometry of each of the three hybridization states. One simple theory explains it all. This theory is called the valence shell electron pair repulsion theory (VSEPR). Stated simply, all orbitals containing electrons in the outermost shell (the valence shell) want to get as far apart from each other as possible. This one simple idea is all you need to predict the geometry around an atom. First, let s apply the theory to the three types of hybridized orbitals. 

The higher the valency of a metal, the greater will be the number of electrons in the outermost shell. Now, since the positive charge residing in the nucleus remains unaltered by the removal of electrons, its attractive influence will progressively increase with the removal of each successive electron. It follows that when there are a number of electrons in the outermost shell, the removal of electrons will progressively tend to be more and more difficult as each electron is taken out. 

Since there are only about 100 electrons total in even the biggest atoms, it can easily be seen that the shells numbered 5 or higher never get filled with electrons. Another important limitation is that the outermost shell, called the valence shell, can never have more than eight electrons in it. The number of electrons in the valence shell is a periodic property. 

EXAMPLE 3.12. What is the maximum number of electrons in the first shell when it is the outermost shell when it is not the outermost shell ... 

The first shell of any atom holds a maximum of two electrons, and the second shell holds a maximum of eight. Thus, the first two electrons of potassium fill the first shell, and the next eight fill the second shell. The outermost shell of any atom can hold at most eight electrons. In potassium, there are nine electrons left, which would fit into the third shell if it were not the outermost shell. However, if we put the nine electrons into the third shell, it would be the outermost shell. Therefore, we put 8 of the remaining electrons in that shell. That leaves the one electron left in the fourth shell. 

How many electrons can fit into an atom in which the outermost shell is the (a) first shell ... 

Ans. Li loses an electron, leaving it with the electron configuration of He. A configuration of two electrons in its outermost shell corresponds to the octet because the outermost shell is the first shell, which can hold only two electrons. 

Ans. Onlv hvdrogen. Lithium and beryllium arc metals, which tend to lose electrons (and form ionic bonds) rather than share. The resulting configuration of two electrons in the first shell, with no other shells occupied, is stable, and therefore is also said to satisfy the octet rule. Second-period elements of higher atomic number tend to acquire the electron configuration of neon. If the outermost shell of an atom is the first shell, the maximum number of electrons in the atom is 2. 

When a sodium atom loses an electron to form Na+, how many electrons are there in what is now the outermost shell in the valence shell ... 

Ans. There are eight electrons in the second shell, which is now the outermost shell, since the one electron in the third shell has been lost. There arc now zero electrons in the valence shell. 

The noble gases, located at the end of each period, have electron configurations of the type ns2np6, where n represents the number of the outermost shell. Also, n is the number of the period in the periodic table in which the element is found. 

Ans. The maximum number of electrons in any outermost shell (except the first shell) is 8. The fifth shell starts before the d subshell of the fourth shell starts. 

Ans. The four areas represent the four s and p orbitals of the outermost shell. If there are at least two electrons in the outermost shell, the first two are paired because they are in the s subshcll. The other electrons do not pair up until all have at least one electron in each area (orbital). 

Ans. A state of great stability is a state in which the outermost s and p subshells are filled and no other subshell of the outermost shell has any electrons. 

The covalent bonding in organic compounds can be described by means of the electron dot notation (Chap. 5). The carbon atoms has four electrons in its outermost shell ... 

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