Diagonal rule

Figure 11.2 Enlarged portions of Segre chart of nuclides, showing s-process (upper chain) and r-process (lower chain). White boxes stable nuclides diagonally ruled boxes unstable nuclides crosshatched boxes highly unstable nuclides.

Among the main group atoms, elements diagonal to each other as indicated by the dashed arrows have similar properties because they have a similar metallic character. The noble gases are nonmetals, but they are an exception to the diagonal rule. 

Figure 14 Selection of time-integrated fluid fluxes from the literature. The average regional, pervasive flow-dominated flux of ni(fluid) m(7ock) (2(r) denoted with diagonal ruled bar (computed using geometric mean ...

Figure 1. Sublett basin (solid line, dashed where uncertain) in relation to major Permian structural and paleogeographic elements. Areal extent of Meade Peak indicated by left diagonal rules Retort, by right diagonal rules limit of middle Permian epicontinental shelf deposits indicated by dotted line. Cross-section A-A shown in Figure 3, B-B in Figure 2.

Under standard-state conditions, any species on the left of a given half-cell reaction will react spontaneously with a species that appears on the right of any halfcell reaction located above it in Table 19.1. This principle is sometimes called the diagonal rule. In the case of the Cu/Zn electrochemical cell... 

Applying the diagonal rule we see that Br2 will oxidize 1 but will not oxidize Cl . Therefore, the only redox reaction that will occur appreciably under standard-state conditions is... 

Applying the diagonal rule, we see that Ag will oxidize Mg ... 

The noble gases (group 18 elements) are nonmetals and are exceptions to the diagonal rule. Noble gases are nearly chemically inert. The heavier noble gases form a number of compounds with oxygen and fluorine such as KrF2 and XeC>4... 

The most metallic element is francium at the bottom left of the table. The most nonmetallic element is fluorine. The metallic character of elements within a group increases with period number. This means that within a column, the more metallic elements are at the bottom. The metallic character of elements within a period decreases with group number. This means that within a row, the more metallic elements are on the left. Among the main group atoms, elements diagonal to each other as indicated by the dashed arrows have similar properties because they have a similar metallic character. The noble gases are nonmetals, but they are an exception to the diagonal rule. 

Strategy To predict what redox reaction(s) will take place, we need to compare the standard reduction potentials of CI2, Br2, and I2 and apply the diagonal rule. 

Strategy At first it may not be clear how to assign the electrodes in the galvanic cell. From Table 19.1 we write the standard reduction potentials of Ag and Mg and apply the diagonal rule to determine which is the anode and which is the cathode. 

An iron container can be covered with a layer of another metal such as tin or zinc. A tin can is made by applying a thin layer of tin over iron. Rust formation is prevented as long as the tin layer remains intact. However, once the surface has been scratched, rusting occurs rapidly. If we look up the standard reduction potentials, according to the diagonal rule, we find that iron acts as the anode and tin as the cathode in the corrosion process ... 

A mnemonic diagram for the building-up order (diagonal rule]... 

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