Atoms gain/loss

Sinee the oxidation number of the combined oxygen atom is 2- throughout, that nf the chromium atom in Cr Or is fi+. that of the O ion is obviously 3+. that of the sulfur atom in SO,- is 4+, and that of the sulfur atom in, SO.r is b+. The total loss in oxidation number by the two chromium atoms is therefore 2 x 6i - (2 x 2) - (t+. Since this loss must he offset by a gain made by the sulfur atoms, and since one sulfur atom gains 2+. the reaction must require 3 sulfur alums. Therefore, the next partially hulanced equation is written as... 

In ionic bonding, atoms gain and lose electrons in order to achieve a noble gas electron configuration. Here s how Lewis symbols show this electron gain and loss in the ionic bonding of sodium chloride ... 

Reduction - gain of ctrons by an atom t or molecule (or loss of O atoms, gain of,Hl atoms,- decrease in positive charge or increase in negative charge). ... 

Oxidation The gain of an oxygen atom or atoms the loss of a hydrogen atom or atoms or the loss of an electron or electrons. 

Reduction is defined as a gain of electrons, gain of hydrogen atoms, or loss of oxygen atoms. A chlorine atom is reduced to a chloride ion by gaining one electron when it reacts with a metal such as sodium ... 

In the reaction of sodium with chlorine, sodium atoms lose their singlevalence electron to produce sodium cations (Na+). Oxidation is the loss of electrons, and sodium has heen oxidized. Except when electrons are flowing through a wire from a negative region to a positive one, they are held to positively charged nuclei. Because we know that matter is neutral, we must ask where the electrons lost in oxidation go. The reaction of sodium with chlorine occurs because as sodium atoms lose electrons, chlorine atoms gain electrons. 

Figure 4.3. In the ionic compound NaCl, both the Na+ ion and the Cr ion have octets of outer shell electrons. The Na ion is formed by the loss of 1 electron from an Na atom (see Figure 4.2) and the Cl ion is formed by a Cl atom gaining an electron.

Chemical reactions involve the gain, loss, or transfer of electrons— particularly valence electrons, which are those found in the outermost orbitals (those furthest away from the nucleus) they are more weakly bound than electrons in orbitals closer to the nucleus. In order to describe reactions, it is convenient to describe atoms in terms of their electronic configuration, which describes the total number of electrons, the orbital where the electrons can be found, and the number of electrons in each orbital. Clearly, a convenient organization of the elements is required in order to find the information we need. This organization is known as the periodic table of the elements. 

Figure 4. lOA shows that each Mg atom loses two electrons and each O atom gains them. This loss and gain is a transfer of electrons away from each Mg atom to each O atom. The resulting Mg + and 0 ions aggregate into an ionic solid. 

Note that calcium has gained in oxidation number from 0 to +2. (Each calcium atom loses two electrons.) We say that calcium has been oxidized. Oxygen, on the other hand, has decreased in oxidation number from 0 to —2. (Each oxygen atom gains two electrons.) We say that oxygen has been reduced. An oxidation-reduction reaction always involves both oxidation (the loss of electrons) and reduction (the gain of electrons). 

The base peak of the spectrum (m/e 218) arises by expulsion of the elements of methyl isocyanate to give XI, the formation of which can be represented as shown although the source of the hydrogen atom gained by XI is not established (6). Loss of the angular methyl group in XI affords XII (small peak at m/e 203), loss of a further methyl radical from... 

When an atom gains or loses an electron, it develops a charge and becomes an ion. In general, the loss or gain of one, two, or sometimes even three electrons can occur, but an element doesn t lose or gain more than three electrons. 

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