Group 2 elements are those that appear in the second column of the periodic table. The group 2 elements are beryllium, magnesium, calcium, strontium, barium and radium. Group 2 elements share a number of characteristics in common.
All group 2 elements in their pure state have two valence electrons (i.e., two electrons in their outermost shell) if they have not been ionised. These electrons are in an s-type orbital. As a general rule of thumb, the ionisation energy (the amount of energy it takes to ionise the atom) is typically greater than for group 1 elements but less than for transition metals or nonmetals.
Although they are less reactive as a general rule than group 1 elements, group 2 elements are highly reactive and hence are never found in isolation in nature. Because they are easily ionised, they often form ionic compounds with nonmetals such as chlorine or oxygen, where the group 2 atom will lose two electrons to the nonmetallic atoms; the positively charged group 2 ion is now attracted to the negatively charged nonmetal ions and thus forms an ionic compound.
In pure form, the group 2 elements display metallic properties, meaning that they are good conductors of heat and electricity. When they form compounds, however, they often become insulators. Calcium carbonate (limestone) and calcium phosphate (bones and teeth), for example, are not good conductors of electricity.