Na Cl Na+ Cl^ -The transfer of a single nega-
tively charged electron from a
neutral sodium atom (Na) to a
neutral chlorine atom (Cl)
Sodium cations held together with equal numbers of chloride anions
by the attraction of their opposite charges (ionic bonds) constitute
the ionic compound NaCl.produces a positively charged
sodium cation and a negatively
charged chloride anion.Figure 1.7. Ionic bonds are formed by the transfer of electrons and the mutual attraction of oppositely
charged ions in a crystalline lattice.
part of the name is simply that of the metal forming the cation, in this case sodium.
The second part of the name is based upon the anion, but has the ending ide. So
the ionic compound of sodium and chlorine is magnesium chloride. As shown by the
preceding example, ionic compounds may consist of ions composed of atoms that have
lost electrons (producing positively charged cations) and other atoms that have gained
electrons (producing negatively charged anions). However, ions may also consist of
groups of several atoms with a net charge. Ammonium ion, NH 4 +, is such an ion. As
shown below, the NH 4 + cation consists of 4 H atoms covalently bonded (by 2 shared
electrons) to a central N atom, with the group of 5 total atoms having a net electrical
charge of +1.
H—N—H
—
—
H
H
Ammonium ion, NH 4 +1.1. THE PROCESS OF MAKING AND BREAKING CHEMICAL BONDS:
CHEMICAL REACTIONS
The preceding section has discussed chemical compounds and the two major kinds
of bonds — covalent bonds and ionic bonds — that hold them together. Next is discussed
the process of making and taking apart chemical compounds, chemical reactions. A
chemical reaction occurs when chemical bonds are broken and formed and atoms are
exchanged to produce chemically different species.
0 Green Chemistry, 2nd ed