Group 1a and 2a elements are highly reactive metals. They are lustrous, are solid at room temperature, and conduct heat and electricity. Many of them react violently with water, and all except for beryllium readily form ionic compounds.
The elements of group 1a are collectively called the alkali metals, and the elements of group 2a are the alkaline earth metals. The alkali metals are lithium, sodium, potassium, rubidium, cesium and francium, and the alkaline earth metals are beryllium, magnesium, calcium, strontium, barium and radium. Hydrogen is placed on the periodic table above group 1a but is not considered part of the group.
All group 1a and 2a elements have low electronegativities. This means that they are more likely to donate electrons than accept them. There are two different scales used to calculate electronegativity, and group 1a and 2a elements have low scores on both of them. In the Pauling scale, francium is the least electronegative element; on the Allen scale, cesium is the least electronegative element.
Beryllium is the sole exception to many of the similarities the two groups of elements share. It does not react with water or steam, and it forms covalent bonds rather than ionic ones. Its compounds are poor conductors and have low melting points.