Chemical Properties of the Representative Elements

We have seen that the metallic character of the elements decreases from left to right across a period and increases from top to bottom within a group. On the basis of these trends and the knowledge that metals usually have low ionization energies while nonmetals usually have high electron affinities, we can frequently predict the outcome of a reaction involving some of these elements. 

Now let us take a closer look at the chemical properties of the representahve elements and the noble gases. (We will consider the chemistry of the transihon metals in Chapter 22.) 

Of course, the most important compound of hydrogen is water, which forms when hydrogen bums in air  

The other alkali metals all form oxides and peroxides (containing the 0 ion). For example, 

Potassium, rubidium, and cesium also form superoxides (containing the O2 ion)  

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