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Figure 2.3: Dmitri Medeleev’s 1871 Early Version of the Periodic Table
Photo of Dmitri Medeleev provided by: кабинет академика Михаила Михайловича Шульца – фото любезно передано мне в собственность вдовой М.М.Шульца Ниной Дмитриевной Шульц
Periodic Table provided by: Den fjättrade ankan
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 2.4 Families of the Periodic Table

Remember that Mendeleev arranged the periodic table so that elements with the most similar properties were placed in the same group. A group, or family of elements, is a vertical column of the periodic table. Elements are placed into families due to their similar properties, characteristics, and reactivities. For example, all of the elements in group 1 (except for hydrogen, which has unique properties) are very reactive and form compounds in the same ratios and with similar properties as other 1 elements. Due to the similarities in their chemical properties, Mendeleev put these elements into the same group and they came to be known as the alkali metals. The alkali metals include: lithium, sodium, potassium, rubidium, cesium, and francium. Alkali metals are among the most reactive metals. This is due in part to their larger atomic radii and low ionization energies, that will be discussed in more details in section 2.8 below. They get their name from ancient Arabic (al qali) because “scientists” of the time found that the ashes of the vegetation they were burning contained a large amount of sodium and potassium. In Arabic, al qali means ashes. Although most metals tend to be very hard, alkali metals have a soft texture, are silvery in color and can be easily cut. They also have low boiling and melting points and are less dense than most elements. Figure 2.4 shows some of the most common families on the periodic table.