Bond The force that holds two atoms together

Review Vocabulary chemical bond the force that holds two atoms together... 

The answer to this question lies in the electron structure of the atoms of the elements involved and the nature of the attractive forces between these atoms. The force that holds two atoms together is called a chemical bond. Chemical bonds may form by the attraction between a positive nucleus and negative electrons or the attraction between a positive ion and a negative ion. 

In previous chapters, you learned that elements within a group on the periodic table have similar properties. Many of these properties depend on the number of valence electrons the atom has. These valence electrons are involved in the formation of chemical bonds between two atoms. A chemical bond is the force that holds two atoms together. Chemical bonds can form by the attraction between the positive nucleus of one atom and the negative electrons of another atom, or by the attraction between positive ions and negative ions. This chapter discusses chemical bonds formed by ions, atoms that have acquired a positive or negative charge. In Chapter 8, you will learn about bonds that form from the sharing of electrons. 

The force that holds two atoms together is called a chemical bond. Chemical bonds form because of attractions between oppositely charged atoms, called ions, or between electrons and nuclei. The outermost, or valence, electrons of atoms are the ones mainly involved in the formation of bonds. The elements within a group of the periodic table typically have the same number of valence electrons. 

Chelating ligand (chelate) a ligand having more than one atom with a lone pair that can be used to bond to a metal ion. (21.3) Chemical hond the force or, more accurately, the energy that holds two atoms together in a compound. (2.6)... 

A covalent bond is a strong attractive force that holds two atoms together by their sharing of electrons. These bonding electrons are attracted simultaneously to both atomic nuclei, and they spend part of the time near one atom and part of the time near the other. If an electron pair is not equally shared, the bond is polar. This polarity results from the difference in electronegativities of the atoms—that is, in the unequal abilities of the atoms to draw bonding electrons to themselves. 

Before considering the structures of molecules, we must begin with a discussion of chemical bonds, the forces that hold atoms together in molecules. There are two types of chemical bonds, the ionic bond and the covalent bond. 

Attractive forces operate between all atoms, but unless the potential energy minimum is at least of the order of RT, the two atoms will not be able to withstand the disruptive influence of thermal energy long enough to result in an identifiable molecule. Thus we can say that a chemical bond exists between the two atoms in H2. The weak attraction between argon atoms does not allow Ar2 to exist as a molecule, but it does correspond to the van Der Waals force that holds argon atoms together in the liquid and solid. 

Bond (chemical hond) the force that holds two or more atoms together and makes them function as a unit. 

The forces that hold bonded atoms together are basically just the same kinds electrostatic attractions that bind the electrons of an atom to its positively-charged nucleus a chemical bond occurs when these same forces are able to act on electrons subject to the simultaneous influence of two nuclei. 

Fundamentally, a chemical bond involves either the sharing of two electrons or the transfer of one or more electrons to form ions. Two atoms of nonmetals tend to share pairs of electrons in what is called a covalent bond. By sharing electrons, the atoms remain more or less electrically neutral. However, when an atom of a metal approaches an atom of a nonmetal, the more likely event is the transfer of one or more electrons from the metal atom to the nonmetal atom. The metal atom becomes a positively charged ion and the nonmetal atom becomes a negatively charged ion. The attraction between opposite charges provides the force that holds the atoms together in what is called an ionic bond. Many chemical bonds are also intermediate in nature between covalent and ionic bonds and have characteristics of both types of bonds. 

Covalent bonds are the forces that hold atoms together as molecules. For example, the two 0-H bonds in water molecules are covalent bonds. The covalent bonds most important in biology (C-C and C-H) have bond energies in the range of 300-400 kJ/mol. 

The hydrogen molecule, H2, provides the simplest example of a covalent bond. When two hydrogen atoms are close to each other, the two positively charged nuclei repel each other, the two negatively charged electrons repel each other, and the nuclei and electrons attract each other, as shown in FIGURE 8.6(a). Because the molecule is stable, we know that the attractive forces must overcome the repulsive ones. Let s take a closer look at the attractive forces that hold this molecule together. 

Why do atoms of different elements reaet What are the forces that hold atoms together in molecules and ions in ionic compounds What shapes do they assume These are some of the questions addressed in this chapter and in Chapter 10. We begin by looking at the two types of bonds—bionic and covalent—and the forces that stabilize them. 

An ionic bond may also be formed between two groups of atoms, or between an atom and a group. We will see in Chapter 5 that these are the forces found holding inorganic crystals together. It is not always easy to predict such an ionic bond from the molecular formula, since the electronegativity of the main atom in a group is influenced and modified by the other atoms covalently bonded to it. 

A molecule is an assembly of two or more atoms tightly bound together. The resultant "package" of atoms behaves in many ways as a single, distinct object, just as a television set composed of many parts can be recognized as a single object. We will discuss the forces that hold the atoms together (the chemical bonds) in Chapters 8 and 9. 

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