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|s-block in the periodic table|
|This article is in a list format that may be better presented using prose. (March 2013)|
The s-block is a block in the periodic table that consists of the first two groups, namely the alkali metals and the alkaline earth metals. The elements in the s-block generally exhibit well-defined trends in their physical and chemical properties, changing steadily moving down the groups. Their properties can be most readily explained in terms of their electron configuration, with their valence electrons occupying s-orbitals. By this definition, hydrogen and helium are sometimes also considered to be part of the s-block.
The modern periodic law states that an element's chemical and physical properties is a periodic function of its atomic number. The long form of the periodic table is based on modern periodic law. The long form is divided into four blocks, s, p, d, and f. In an atom of an s-block element,the last electron enters the s-orbital of the outermost electron shell: