Molecules covalent bonding

Hydrogen molecule covalent bonding by way of a shared electron pair... 

However, science evolves More will be seen of the quantum mechanical approach to solvation and in particular in nonaqueous solutions when there is more chance of interactions involving overlap of the orbitals of transition-metal ions and those of organic solvent molecules. Covalent bond formation enters little into the aqueous calculations because the bonding orbitals in water are taken up in the bonds to hydrogen. With organic solvents, the quantum mechanical approach to bonding may be essential. 

The second type of bonding, covalent bonding, occurs with elements like carbon in the middle of the periodic table, which would otherwise have to gain or lose several electrons to form an ion with a complete valence shell. A covalent bond is a two-electron bond, and a compound with covalent bonds is called a molecule. Covalent bonds also form between two elements from the same side of the table, such as two hydrogen atoms or two chlorine atoms. H2, CI2, and CH4 are aU examples of covalent molecules. 

Example For solid Zn, 274 pm between nuclei, so r (atomic radius) = 137 pm For nometallic elements, r is determined for diatomic molecules (covalent bond). 

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. 

Although much weaker than a covalent bond, the H-bond is considerably stronger than most nonspecific nonbonding interactions. To be somewhat more quantitative, H-bonds between neutral molecules, e.g., the water dimer, are generally bound by some 2-15 kcal/mol in the gas phase, relative to the separate molecules. Covalent bonds frequently exceed 100 kcal/mol in binding energy, whereas van der Waals interactions like those between two hydrocarbons are commonly less than 2 kcal/mol. 

Table 10.G Comparison of Atomic Separations UJithin Molecules (Covalent Bonds) and Betujeen Molecules (Intermolecular Interactions) ...

Models and hydrocarbons Chemists represent organic molecules in a variety of ways. Figure 21.4 shows four different ways to represent a methane molecule. Covalent bonds are represented by a single straight line, which denotes two shared electrons. Most often, chemists use the type of model that best shows the information they want to highlight. 

Intermolecular crosslink Covalent bonds formed in vivo between a side group of one molecule and a side group of another molecule covalent bonds formed between a side group of one molecule and one end of a bifunctional agent and between a side group of a second molecule and the other end of a bifunctional agent. 

Chemists have made outstanding progress in understanding bonding principles which primarily explore how molecules make and break bonds thereby accounting for stability and reactivity of molecules. Covalent bonds result from the interaction... 

A bond where electrons are equally shared between two atoms producing a stable electron configuration and a very stable molecule. Covalent bonds are the strongest of the molecular bonds. 

In the first part of this chapter, we examined atomic structure and atomic orbitals and began a study of the collections of atoms called molecules. Now we will enlarge the discussion to include molecular orbitals, the regions of space occupied by electrons in molecules. Covalent bonding between atoms involves the sharing of electrons. This sharing takes place through overlap of an atomic orbital with another atomic orbital or with a molecular orbital. 

Molecular transition Trarrsition of a molecule (covalently bonded) from the ground to an excited state via electron promotion among molecular orbitals. 

Admittedly, chemistry can generate fear. That is especially true when you hear your friends talking about their experiences. If your professor has chosen this textbook for your preparative chemistry course, I feel that you are on your way to an enjoyable experience. Sure we talk about atoms, molecules, covalent bonds, and ionic bonds. We talk about chemical reactions, solution chemistry, acids and bases, and gas laws. You will indeed encounter such seemingly ridiculous terms as stoichiometry, the mole, chemical equilibrium, molarity, and oxidation and reduction. You will also encounter things so incredibly small that you will wonder how scientists can even know they exist. 

For nometallic elements, r is determined for diatomic molecules (covalent bond). 

Polymers are made up of monomer molecules covalently bonded into chains or networks. 

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