The alkaline earth metals are a group of chemical elements in the periodic table with very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure and readily lose their two outermost electrons to form cations with charge +2. In the modern IUPAC nomenclature, the alkaline earth metals comprise the group 2 elements.

The alkaline earth metals are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). This group lies in the s-block of the periodic table as all alkaline earth metals have their outermost electron in an s-orbital.

All the discovered alkaline earth metals occur in nature. Experiments have been conducted to attempt the synthesis of unbinilium (Ubn), which is likely to be the next member of the group, but they have all met with failure. However, unbinilium may not be an alkaline earth metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements.

The boron group is the series of elements in group 13 (IUPAC style) of the periodic table, comprising boron (B), aluminium (Al), gallium (Ga), indium (In), thallium (Tl), and ununtrium (Uut). The elements in the boron group are characterized by having three electrons in their outer energy levels (valence layers). These elements have also been referred to as earth metals and as triels.

Boron is classified as a metalloid while the rest, with the possible exception of ununtrium, are considered poor metals. Ununtrium has not yet been confirmed to be a poor metal and, due to relativistic effects, might not turn out to be one. Boron occurs sparsely, probably because bombardment by the subatomic particles produced from natural radioactivity disrupts its nuclei. Aluminium occurs widely on earth, and indeed is the third most abundant element in the Earth's crust (8.3%). Gallium is found in the earth with an abundance of 13 ppm. Indium is the 61st most abundant element in the earth's crust, and thallium is found in moderate amounts throughout the planet. Ununtrium is never found in nature and therefore is termed a synthetic element.