A group is the set of all elements in the same vertical column of the periodic table. Elements in the same group have similar chemical properties because they have the same number of valence electrons (the outermost electrons that take part in bonding). For example, the elements of Group 1 are all reactive metals that form ions with a +1 charge.

族是周期表中同一纵列的所有元素。同一族的元素化学性质相似,因为它们具有相同数目的价电子(参与成键的最外层电子)。例如,第 1 族元素都是活泼金属,均形成带 +1 电荷的离子。