Alkali metals Group valence electrons

Two lithium atoms each transfer a single electron to one sulfur atom to yield the ionic compound U2S. As an alkali metal (Group lA), lithium easily gives up its single valence electron. As a Group VIA nonmetal, sulfur readily accepts two additional electrons into its valence shell. 

The group in the Periodic Table with the least complicated chemistry is almost certainly the alkali-metal group lithium (Z — 3), sodium (Z 11), potassium (Z = 19), rubidium (Z 37), cesium (Z = 55), and the recently discovered francium (Z = 87). These elements follow directly after the inert gases and thus have one single valence electron beyond a well-shielded nucleus. 

Alkali Metals Group 1 All group 1 metals have one valence electron. When they form ions, they will have a charge of 1+. Group 1 alkali metals are highly reactive and will react vigorously with water. 

The electron sea model for metals postulates a regular array of cations in a "sea" of valence electrons, (a) Representation of an alkali metal (Group 1A) with one valence electron, (b) Representation of an alkaline earth metal (Group 2A) with two valence electrons. 

For representative elements the number of valence electrons in an atom corresponds to the number of the group or family in which the atom is found. For example, elements such as hydrogen and sodium (in fact, all alkali metals. Group lA or 1) have a valence of 1 (or one valence electron). From left to right in period 2, beryllium. Be (Group llA or 2), has two valence electrons boron, B (Group lllA or 3), has three carbon, C (Group IVA or 4), has four and so forth. 

In Figure 8.1, electrical resistivities (inversely proportional to conductivities) of the solid main group elements are plotted. At the far left are the alkali metals, having low resistivities (high conductances) at the far right are the nonmetals. Metals contain valence electrons that are relatively free to move and thereby conduct current. In most cases, non-metals contain mnch more localized electrons and covalently bonded pairs that are less mobile. Oraphite (Section 8.6.1), an allotrope (elanental form) of the nonmetal carbon, is an exception that has a mnch greater ability to condnct than most nonmetals because of delocalized electrons. 

In Table 6.2 we saw that the total number of orbitals in each shell equals r 1,4,9, or 16. Because we can place two electrons in each orbital, each shell accommodates up to 2rf electrons 2,8,18, or 32. We see that the overall structure of the periodic table reflects these electron numbers Each row of the table has 2, 8, 18, or 32 elements in it. As shown in T Figure 6.30, the periodic table can be further divided into four blocks based on the filling order of orbitals. On the left are two blue columns of elements. These elements, known as the alkali metals (group lA) and alkaline earth metals (group 2A), are those in which the valence s orbitals are being filled. These two columns make up the 5 block of the periodic table. 

The Group 2A elements (the alkaline earth metals) have higher first ionization energies than the alkali metals (Group lA). The alkaline earth metals have two valence electrons (the outermost electron configuration is ns ). Because these two s electrons... 

In Mendeleev s periodic table, the alkali metals (group 1) and the coinage metals (group 11) appear together as group I. The only similarity between the two subgroups, however, is that both have a single s electron in the valence... 

The alkali metals also release their valence electrons when they dissolve in liquid ammonia, but the outcome is different. Instead of reducing the ammonia, the electrons occupy cavities formed by groups of NH3 molecules and give ink-blue metal-ammonia solutions (Fig. 14.14). These solutions of solvated electrons (and cations of the metal) are often used to reduce organic compounds. As the metal concentration is increased, the blue gives way to a metallic bronze, and the solutions begin to conduct electricity like liquid metals. 

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