The others there is not much of a shift in the

This preview shows page 6 - 8 out of 55 pages.

the others, there is not much of a shift in the electron cloud, and the partial charges are small. When the difference in electron‑attracting abilities is negligible (or zero), the atoms in the bond will have no significant partial charges. We call this type of bond a nonpolar covalent bond . The covalent bond between hydrogen atoms in H 2 is an example of a nonpolar covalent bond. H Cl Chlorine attracts electrons more. Hydrogen attracts electrons less. δ− δ+ Electrons shift toward the chlorine atom, forming partial plus and minus charges. 74 Chapter 3 Chemical Compounds
Image of page 6

Subscribe to view the full document.

3.2 Compounds and Chemical Bonds 75 Transfer of Electrons Sometimes one atom in a bond attracts electrons so much more strongly than the other that one or more electrons are fully transferred from one atom to another. This commonly happens when metallic atoms combine with nonmetallic atoms. A nonmetallic atom usually attracts electrons so much more strongly than a metallic atom that one or more electrons shift from the metallic atom to the nonmetallic atom. For example, when the element sodium combines with the element chlorine to form sodium chloride, NaCl, the chlorine atoms attract electrons so much more strongly than the sodium atoms that one electron is transferred from each sodium atom to a chlorine atom. When an electron is transferred completely from one uncharged atom to another, the atom that loses the electron is left with one more proton than electron and acquires a + 1 charge overall. It therefore becomes a cation (Section 3.4). For example, when an uncharged sodium atom with 11 protons and 11 electrons loses an electron, it is left with 11 protons (a charge of + 11) and 10 electrons (a charge of 10), yielding an overall + 1 charge. Na Na + + e 11p/11e 11p/10e + 11 + ( 11) = 0 + 11 + ( 10) = + 1 In contrast, an uncharged atom that gains an electron will have one more electron than proton, so it forms an anion with a 1 charge. When a chlorine atom gains an electron from a sodium atom, the chlorine atom changes from an uncharged atom with 17 protons and 17 electrons to an anion with 17 protons and 18 electrons and an overall 1 charge. Cl + e Cl 17p/17e 17p/18e + 17 + ( 17) = 0 + 17 + ( 18) = 1 Atoms can transfer one, two, or three electrons. Thus cations can have a + 1, + 2, or + 3 charge, and anions can have a 1, 2, or 3 charge. Because particles with opposite charges attract each other, there is an attraction between cations and anions. This attraction is called an ionic bond . For example, when an electron is transferred from a sodium atom to a chlorine atom, the attraction between the + 1 sodium cation and the 1 chlorine anion is an ionic bond (Figure 4.5). You will see as you read more of this book that substances that have ionic bonds are very different from those that have all covalent bonds. For example, compounds that have ionic bonds, such as the sodium chloride in table salt, are solids at room temperature and pressure, but compounds with all covalent bonds, such as hydrogen chloride and water, can be gases and liquids as well as solids.
Image of page 7
Image of page 8
You've reached the end of this preview.
  • Fall '06
  • Mark
  • Atom, atoms, Chemical bond

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern