Nonmetals diatomic elements

Seven nonmetal elements are found naturally as molecular elements of two identical atoms. The elements whose natural state is diatomic are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. Their formulas can be written as H2, N2, O2, F2, Cb, Br2, and b, respectively. These molecules are referred to as diatomic elements. All except bromine and iodine are gases at room temperature Br2 is a liquid, and b is a solid. 

Seven elements, all of them nonmetals, do not exist as individual atoms in their pure form. Rather, for reasons you will learn later (see The Diatomic Elements table below), two (sometimes more) atoms join together to form a molecule, a particle composed of two or more atoms bonded together. These seven elements exist as diatomic molecules (di-meaning two, -atomic meaning atom), and are listed in the following table. 

For metals such as sodium, the atomic radius is defined as half the distance between adjacent nuclei in a crystal of the element as shown in Figure 6.10. For elements that commonly occur as molecules, such as many nonmetals, the atomic radius is defined as half the distance between nuclei of identical atoms that are chemically bonded together. The atomic radius of a nonmetal diatomic hydrogen molecule (H2) is shown in Figure 6.10. 

B Aluminum forms an amphoteric oxide in which it has the oxidation state +3 therefore, aluminum is the element. 14.3B Hydrogen is a nonmetal and a diatomic gas at room temperature. It has an intermediate electronegativity (x — 2.2), so it forms covalent bonds with nonmetals and forms anions in combination with metals. In contrast, Group 1 elements are solid metals that have low electronegativities and form cations in combination with nonmetals. 

Nitrogen is a colorless diatomic gas. Phosphorus has several elemental forms, but the most common is a red solid that is used for match tips. Arsenic and antimony are gray solids, and bismuth is a silvery solid. Classify these elements of Group 15 as metals, nonmetals, or metalloids. 

As a nonmetal, chlorine exists as a greenish-yellow gas that is corrosive and toxic at room temperatures. As a halogen, chlorine is not found in the elemental (atomic) state but forms diatomic gas molecules (Cl j). As a very active negative ion with the oxidation state of —1, chlorine forms bonds with most metals found in groups I and II. 

We assume that we have a solid metal M which reacts with a diatomic, gaseous nonmetal X2 (e.g., CI2, F2, 02). Similar cycles can be written for solid elements such as sulfur as the nonmetal. In either case, before we can connect U with AHf we must form gaseous ions of M and X. We need not only the relevant ionization potentials (IP) and electron affinities (EA), but also the heats of atomization of solid M and gaseous X2. These atomization energies are traditionally referred to as heats of sublimation AHsuh of M(s) and of dissociation AHd ss of X2. For NaCl itself, we have... 

If you were asked to produce at ordinary temperatures a sample consisting of the free atoms of an element, your only choice would be a Group 18 element, one of the noble gases. All the other elements occur with their atoms linked together in some way. The nonmetallic elements exist as molecules, such as the diatomic species H2, N2, 02, F2, Cl2, Br2, and I2, and the polyatomic species P4 and S8. Elements near the border between metals and nonmetals can form solids with an extended network of atoms, such as the graphite or diamond forms of carbon and crystalline silicon. There are also countless examples of diatomic, polyatomic, and extended network compounds between different nonmetallic elements, including the millions of organic compounds. 

The terms AHam and AHax constitute the enthalpies of atomization of the element and the nonmetal respectively, AHei is the ionization enthalpy of the metal, AHae is the ionization enthalpy of the nonmetal, and U0 is the lattice energy. For gaseous diatomic nonmetals, AHax is the enthalpy for dissociation (i.e., bond energy... 

Some other free (uncombined) elements also occur in different forms. Different forms of the same element are called allotropes of each other. Except for oxygen, the elements that form diatomic molecules when uncombined do not form allotropes, but many other nonmetals do. The allotropes of carbon— diamond and graphite—are perhaps best known to the general public. Sulfur and phosphorus are also notable for forming allotropes. 

The radius of a nonmetal atom is often determined from a diatomic molecule of an element. 

Explain why the gaseons nonmetals exist as diatomic molecules, but other gaseous elements exist as single atoms. (Chapter 9)... 

What is a molecular element Name the seven nonmetals that exist naturally as diatomic molecular elements. 

The halogens are electronegative and oxidizing elements, fluorine exceptionally so. They occur in nature as halides, and form highly reactive diatomic molecules. Molecular halides are formed with most nonmetals, ionic halides with metals. Some halides are good Lewis acids, and many halide complexes are known. 

For nonmetals there is no single rule. Carbon, for example, exists as an extensive three-dimensional network of atoms, and so we use its empirical formula (C) to represent elemental carbon in chemical eqnations. Bnt hydrogen, nitrogen, oxygen, and the halogens exist as diatomic molecules, and so we use their molecular formulas (H2, N2, O2, F2, CI2, Br2,12) in equations. The stable form of phosphorus is molecular (P4), and so we use P4. For sulfur chemists often nse the empirical formula (S) in chemical equations, rather than Sg which is the stable form. Thus, instead of writing the equation for the combnstion of sulfur as... 

The first three members of Group 6A (oxygen, sulfur, and selenium) are nonmetals, and the last two (tellurium and polonium) are metalloids (Figure 8.19). Oxygen is a diatomic gas elemental sulfur and selenium have the molecular formulas Sg and Seg, respectively tellurium and polonium have more extensive three-dimensional structures. 

The total energy needed for ion formation is even greater than this because metallic lithium and diatomic fluorine must first be converted to separate gaseous atoms, which also requires energy. Despite this, the standard heat of formation (A//f) of solid LiE is —617 kJ/mol that is, 617 kJ is released when 1 mol of LiF(5) forms from its elements. The case of LiF is typical of many reactions between active metals and nonmetals despite the endothermic electron transfer, ionic solids form readily, often vigorously. Figure 9.6 shows another example, the formation of NaBr. 

Unlike the group 6A elements, all the halogens are typical nonmetals. Their melting and boiling points increase with increasing atomic number. Fluorine and chlorine are gases at room temperature, bromine is a liquid, and iodine is a solid. Each element consists of diatomic molecules E2, CI2, Br2, and I2 ( FIGURE 7.27). 

The halogens (group 7A) are nonmetals that exist as diatomic molecules. The halogens have the most negative electron affinities of the elements. Thus, their chemistry is dominated by a tendency to form 1— ions, especially in reactions with metals. 

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