Diagonal relationships in the periodic table

Diagonal relationships in the periodic table exist as well as the vertical relationships. For example, Be and Al are similar in some of their properties, as are B and Si. Rationalize why these diagonal relationships hold for properties such as size, ionization energy, and electron affinity. 

Give some illustrations of diagonal relationships in the periodic table, and explain each. 

Figure 14.2 Three diagonal relationships in the periodic table. Certain Perbd 2 elements exhibit behaviors that are very similar to those of the Period 3 elements immediately below and to the right. Three such diagonal relationships exist Li and Mg, Be and Al, and B and Si.

Alkaline earth metals are involved in two key diagonal relationships in the periodic table, (a) Give the two pairs of elements in these diagonal relationships, (b) For each pair, cite two similarities that demonstrate the relationship, (c) Why are the members of each pair so similar in behavior ... 

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