Ionic bonding metal with nonmetal

But the nature of the compounds formed when the metal and nonmetal are closer to the center of the periodic table is less obvious. Their electronegativities are closer together. And the electronegativity difference between the atoms in a compound determines the nature of the bond. Recall that differences of 1.7 or more result in ionic bonds atoms with differences less than 1.7 form bonds with some covalent character. Lead sulfide (PbS) is an example of such a compound. Lead has an electronegativity of 1.9 sulfur is 2.5. The difference of 0.6 is less than 1.7, so the bond between them should have some covalent character. Like sodium chloride, lead sulfide is a crystalline compound. However, it is dark and shiny, quite unlike salt. It is also insoluble in water, which indicates a high degree of covalency in the lead-sulfur bond, just as one would expect. 

Most binary compounds (made of two etements) of metals with nonmetals are essentially ionic. All compounds involving only nonmetals are essentially covalent except for compounds containing the ion. Practically all tertiary compounds (made of three elements) contain covalent bonds. If one or more of the elements is a metal, there is likely to be ionic as well as covalent bonding in the compound. 

In the previous section, the ionic bond and the reaction of metals with nonmetals to form ionic compounds were discussed. In this section, we examine the nature of the bond between atoms of two nonmetals, those elements to the right of the stair step on the periodic table. You will recall that in reactions between metals and nonmetals, metals lose electrons to form cations and nonmetals acquire them to from anions. But what if both elements are nonmetals Nonmetals, like O, Br, or N, do not lose electrons easily if anything, they prefer to acquire them. As a result, when two nonmetals bond to one another, they do so by sharing electrons forming bonds described as covalent. A covalent bond is a pair of electrons shared by two atoms. Compounds that are held together by covalent bonds are called covalent compounds, and they exist as individual molecules. Covalent bonding provides a second way for atoms to acquire an octet of electrons in their valence shells. The pair of electrons shared by two atoms becomes part of the valence shell of both atoms. 

In general, atoms of metals bond ionically with atoms of non-metals, atoms of metals bond metallically with each other, and atoms of nonmetals bond covalently with each other. 

The compound is ionic — a metal (Al) bonded to a nonmetal (Cl). All ionic compounds are solids at room temperature and pressure. Aluminum has 13 electrons. As an ion, it will lose 3 electrons to become isoelectronic with neon. Thus the aluminum ion will have the electronic configuration ls22s22p6. 

Metals react with nonmetals to form ionic bonds, and nonmetals react with other non-metals to form covalent bonds. 

Chlorine forms ionic bonds with almost all the metals and molecular bonds with the semimetals and nonmetals. With group 1 metals it produces well-known salts when chlorine s —1 ion combines with this group s +1 ions (e.g, NaCl, LiCl, and KCl). Group 2 metals have +2 ions and thus, when combined with —1 ions of chlorine, form salts such as magnesium chloride (MgCl ), calcium chloride (CaCy, and barium chloride (BaCy. 

VIA nonmetals) very easily gain new valence electrons. So metals and nonmetals tend to form bonds in which the metal atoms entirely surrender valence electrons to the nonmetals. Bonds with extremely unequal electron-sharing are called ionic bonds. 

Ionic compounds consist of positive ions (cations) and negative ions (anions) hence, ionic compounds often consist of a metal and nonmetal. The electrostatic attraction between a cation and anion results in an ionic bond that results in compound formation. Binary ionic compounds form from two elements. Sodium chloride (NaCl) and sodium fluoride (NaF) are examples of binary ionic compounds. Three elements can form ternary ionic compounds. Ternary compounds result when polyatomic ions such as carbonate (C032 ), hydroxide (OH-), ammonium (NH4+), form compounds. For example, a calcium ion, Ca2+, combines with the carbonate ion to form the ternary ionic compound calcium carbonate, CaC03. Molecular compounds form discrete molecular units and often consist of a combination of two nonmetals. Compounds such as water (H20), carbon dioxide (C02), and nitric oxide (NO) represent simple binary molecular compounds. Ternary molecular compounds contain three elements. Glucose ( 12 ) is a ternary molecular compound. There are several distinct differences between ionic and molecular compounds, as summarized in Table 1.2. 

The Alkali Metals.—Bonds of the alkali metals with all nonmetals are essentially ionic (with more than 50 percent ionic character—electronegativity difference greater than 1.7) except for Li—I, Li—C, and Li—S, with about 43 percent ionic character. 

The first thing you must be able to do in order to predict molecular shapes is to draw an electron-dot formula, so we ll tackle that subject first Including H, there are 16 active nonmetals for which you should know the numbers of valence electrons in the uncombined atoms Except for H (which has only one s electron), these elements are all found to the right of the diagonal in the p block of the periodic table (see inside front cover) Each atom has two v electrons in its valence shell, the number ofp electrons is different for different atoms (Basically, we are uninterested in metals here, metals rarely form predominantly covalent bonds, but tend to form ionic bonds ignore the noble gases, with an already filled s-yi6 unreactive )... 

Metals form alloys with each other. They form ionic compounds with nonmetals. Nonmetals form only covalently bonded compounds with each other. As a result, metals become only positively (+) charged ions, whereas nonmetals become either negatively (-) or positively (+) charged ions. 

Metallic and nonmetalbc elements can react with each other to form com-ponnds by transferring electrons from the metal atoms to the nonmetal atoms. The ions formed attract each other becanse of their opposite charges, and these attractions are called ionic bonds. However, in a sobd ionic compound, a single pair of ions does not bond together instead, an almost inconceivably huge number of both types of ions forms a lattice that extends in three dimensions. The three-dimensional nature of the sodium chloride structure (Figure 5.9) is typical of ionic solids. 

Metals with high oxidation numbers tend to act somewhat like nonmetals. For example, many transition metals form oxoanions, such as permanganate ion, chromate ion, and dichromate ion, in which the metal is covalently bonded to oxygen. The ability to form covalent bonds to oxygen is evidence of these metals more covalent nature. (In their low oxidation states, most metals typically exist in ionic compounds as monatomic cations.) Titanium(lV) chloride is an example of a compound in which the... 

Explain why metals usually combine with nonmetals to form ionic bonds. 

An ionic bond is formed when two ions with opposite charges join together. Ionic bonds are particularly strong. One example of an ionic compound is table salt (sodium chloride), which is formed by the reaction between the metallic element sodium (Na) and the nonmetal chlorine (Cl). 

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