As scientists search the universe for signs of life on other planets they are likely to focus on the presence of molecules containing which of the following elements?
a. carbon
b. calcium
c. iron
d. magnesium

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.