The s-block elements are the 14 elements contained within these columns. All of the s-block elements are unified by the fact that their valence electrons (outermost electrons) are in an s orbital. The s orbital is spherical and can be occupied by a maximum of two electrons. Elements in column 1 have one electron in the s orbital, and elements in column 2 (plus helium) have two electrons in the s orbital.

The s-block elements include hydrogen (H), helium (He), lithium (Li), beryllium (Be), sodium (Na), magnesium (Mg), potassium (K), calcium (Ca), rubidium (Rb), strontium (Sr), cesium (Cs), barium (Ba), francium (Fr) and radium (Ra).