Electron configurations octet rule

Since each hydrogen atom has two electrons and the oxygen atom has eight electrons, the octet rule is satisfied. In H +, the atom would have no electrons, which is not the electronic configuration of a noble gas. 

The correlation of nuclear stability with special numbers of nucleons is reminiscent of the correlation of chemical stability with special numbers of electrons— the octet rule discussed in Section 6.12. In fact, a shell model of nuclear structure has been proposed, analogous to the shell model of electronic structure. The magic numbers of nucleons correspond to filled nuclear-shell configurations, although the details are relatively complex. 

Lewis summarized much of his theory of chemical bonding with the octet rule. According to the octet rule, atoms will lose, gain, or share electrons in order to achieve a noble gas electron configuration. This rule enables us to predict many of the formulas for compounds consisting of specific elements. The octet rule holds for nearly all the compounds made up of second period elements and is therefore especially important in the smdy of organic compounds, which contain mostly C, N, and O atoms. 

When ionic bonds form, the atoms of one element lose electrons and the atoms of the second element gain them until both types of atoms have reached a noble-gas configuration. The same idea can be extended to covalent bonds. However, when a covalent bond forms, atoms share electrons until they reach a noble-gas configuration. Lewis called this principle the octet rule ... 

The octet rule tells us that eight electrons fill the outer shell of an atom to give a noble-gas ns1ns(l valence-shell configuration. However, when the central atom in a molecule has empty d-orbitals, it may be able to accommodate 10, 12, or even more electrons. The electrons in such an expanded valence shell may be present as lone pairs or may be used by the central atom to form additional bonds. 

It must lose two electrons in its 3s orbital to obey the octet rule. This creates a magnesium ion with a charge of +2. Thus, a magnesium ion has the same electron configuration as the sodium ion but a different charge. Both ions have the same stable electron configuration as the noble gas neon ... 

A The noble gases exhibit the highest ionization energies because, according to the octet rule, they have optimal electron configurations. The ionization energies of the alkali metals are correspondingly low. 

When the electron configurations of the elements were worked out, it became clear that the valence electrons of the period 2 elements must be accommodated in just four orbitals, the 2s and the three 2p orbitals. In the localized orbital model it is assumed that each bond can be described by a localized orbital formed by the overlap of one orbital on each of the bonded atoms. According to this model, therefore, a period 2 element can form bonds with at most four ligands so that electron configurations appeared to provide a justification for the octet rule. 

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. 

It must be emphasized that the octet rule does not describe the electron configuration of all compounds. The very existence of any compounds of the noble gases is evidence that the octet rule does not apply in all cases. Other examples of compounds that do not obey the octet rule are BF,. PF5, and SF6. But the octet rule does summarize, systematize, and explain the bonding in so many compounds that it is well worth learning and understanding. Compounds in which atoms attain the configuration of helium (the duet) are considered to obey the octet rule, despite the fact that they achieve only the duet characteristic of the complete first shell of electrons. 

It must be emphasized that the duodectet rule (4.6) initially has no structural connotation, but is based on composition only. Indeed, the compositional regularity expressed by (4.6) encompasses both molecular species (such as the metal alkyls) and extended lattices (such as the oxides and halides) and therefore appears to transcend important structural classifications. Nevertheless, we expect (following Lewis) that such a rule of 12 may be associated with specific electronic configurations, bond connectivities, and geometrical propensities (perhaps quite different from those of octet-rule-conforming main-group atoms) that provide a useful qualitative model of the chemical and structural properties of transition metals. 

The tendency of atoms to make the number of their valence electrons eight, like the nobel gases, is known as the octet rule. There are two ways for the elements to gain their octet and obtain a noble gas electron configuration. 

Atoms tend to acquire a noble gas configuration either by forming ions or by sharing electrons in covalent bonds. The tendency of atoms to acquire eight valence electrons is known as the octet rule. 

The period 2 non-metals from carbon to fluorine must fill their 2 s and their three 2p orhitals to acquire a nohle gas configuration like that of neon. Covalent bonding that involves these elements obeys the octet rule. In the formation of the diatomic fluorine molecule, F2, for example, the bonding (shared) pair of electrons gives each fluorine atom a complete valence level. 

As mentioned previously, in 1916, Lewis noted that noble gases were particularly stable and did not form compounds. Lewis used these facts to formulate the octet rule. The noble gases have their outer electron shell filled with eight electrons. (Helium is an exception with only two electrons in its outer shell.) The octet rule says that the most stable electron configuration of an atom occurs when that atom acquires the valence electron configuration of a noble gas. That is, when an atom can acquire eight (octet) electrons in its valence shell (or two for hydrogen to become like helium). 

In summary, ionic bonds form when there is a transfer of electrons between atoms of different elements. The result of this transfer produces oppositely charged ions. The ions produced generally obtain the valence electron configuration of noble gases, that is, conform to the octet rule. The oppositely charged ions produced are held together by electrostatic attraction. This attractive force is the ionic bond. 

Lewis and many other chemists had recognized the shortcomings of the ionic bond. When diatomic molecules, such as or Cl, were considered, there was no reason why one atom should lose an electron and an identical atom should gain an electron. There had to be another explanation for how diatomic molecules formed. We have seen how the octet rule applies to the formation of ionic compounds by the transfer of electrons. This rule also helps explain the formation of covalent bonds when molecules (covalent compounds) form. Covalent bonds result when atoms share electrons. Using fluorine, F, as a representative halogen, we can see how the octet rule applies to the formation of the molecule. Each fluorine atom has seven valence electrons and needs one more electron to achieve the stable octet valence configuration. If two fluorines share a pair of electrons, then the stable octet configuration is achieved ... 

Nucleon a proton or a neutron, the number of nucleons in an atom equals the sum of protons and neutrons in the nucleus Octet Rule general rule that states that the most stable electron configuration occurs when an atom surrounds itself with eight valence electrons... 

The XeF2 molecule is linear. According to the octet rule, which is assumed to apply to the central atoms of most main group compounds and which states that such central atoms combine with other atoms until they have a share in eight electrons, i.e. an s2p6 configuration is produced, the xenon atom should be zerovalent. 

When atoms combine to produce molecules, they often do so in accord with the octet rule. Your text undoubtedly contains a fairly detailed discussion of the octet rule. In essence, it may be described as the tendency for an atom to lose, gain, or share electrons in order to achieve an s2p6 configurationin 1 e 0uter most shell. The simplest atoms (H, Li, Be, and so on) tend to achieve a Is2 configuration, according to what might be called the duet rule. 

Why does the octet rule work What factors determine whether an atom is likely to gain or to lose electrons Clearly, electrons are most likely to be lost if they are held loosely in the first place—that is, if they feel a relatively low effective nuclear charge, Zeff, and therefore have small ionization energies. Valence-shell electrons in the group 1A, 2A, and 3A metals, for example, are shielded from the nucleus by core electrons. They feel a low Zeff, and they are therefore lost relatively easily. Once the next lower noble gas configuration is reached, though, loss of an additional electron is much more difficult because it must come from an inner shell where it feels a high Zeff. 

The tendency of main-group atoms to fill their s and p subshells when they form bonds—the octet rule discussed in Section 6.12—is an important guiding principle that makes it possible to predict the formulas and electron-dot structures of a great many molecules. As a general rule, an atom shares as many of its valence-shell electrons as possible, either until it has no more to share or until it reaches an octet configuration. For second-row elements in particular, the following guidelines apply ... 

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