Q. Describe about groups or families in periodic table?

Every element may be represented by a one or two letter symbol. In the middle of nineteenth century a Russian chemist Dmitri Mendeleev saw that elements could be arranged according to repeating patterns of properties. Mendeleev's preparation has evolved into the periodic table of the elements that you can see inside the back cover of this Handbook. The vertical columns of elements are called as groups or families. The elements in a group have alike properties. A Horizontal row on the periodic table is called as periods. When a new period begins the elements tend to repeat the properties of the elements above them in the previous period. The value of Mendeleev's table was that it accurately predicted the properties of elements that had not yet been discovered.