Oxygen gain

May was the first to stress the important role pf CujClj within the pits on the mechanism, and he considered that it acted as a screen that prevented dissolved oxygen gaining access to the bottom of the pit thus preventing the formation of a protective CujO film the low solubility of CU2CI2 also maintained the activity of copper ions at a low value and thus facilitated anodic dissolution of the copper. 

Metallic iron is made up of neutral iron atoms held together by shared electrons (see Section 10.7). The formation of rust involves electron-transfer reactions. Iron atoms lose three electrons each, forming Fe cations. At the same time, molecular oxygen gains electrons from the metal, each molecule adding four electrons to form a pair of oxide anions. As our inset figure shows, the Fe cations combine with O anions to form insoluble F 2 O3, rust. Over time, the surface of an iron object becomes covered with flaky iron(ni) oxide and pitted from loss of iron atoms. 

In order to achieve a noble gas configuration, oxygen gains two electrons, forming the stable dianion. The Lewis structure for O2 is shown below. 

Figure 4.25 101 twinning in Ti02 (rutile) (a) Ti twin plane, no composition change (b) O twin plane, oxygen loss and (c) O twin plane, oxygen gain. 

Two zinc atoms combine with one diatomic oxygen molecule to form two formula units of zinc oxide. Because zinc loses four electrons in the oxidation reaction and oxygen gains four electrons in the reduction reaction, all electrons are accounted for the two half-reactions are balanced. 

EXAMPLE 1 What is the empirical formula for lithium oxide Lithium loses one electron to achieve the He structure and thus forms lithium ion, Li, Oxygen gains two electrons to achieve the Ne structure and thus forms oxide ion,. To preserve neutrality, the compound must be Li20. 

Calcium has lost both its 4s electrons and oxygen gained them in its 2p-subshell. 

The intermediate has a positive charge on the oxygen derived from water, but this is neutralised by losing the attached proton such that the oxygen gains the electrons in the O-H... 

Reduction refers to losing oxygen, gaining hydrogen, or gaining one or more electrons. It is a decrease in the oxidation number. It s also a decrease in the valence number of the atom. 

A combination reaction between a metal and a nonmetal, as in Equation 3.6, produces an ionic solid. Recall that the formula of an ionic compound can be determined from the charges of its ions. (Section 2.7) When magnesium reacts with oxygen, the magnesium loses electrons and forms the magnesium ion, The oxygen gains... 

---