On the periodic table, a group of elements is a column of elements. These columns are also known as families, which indicates that the elements within a group will share certain characteristics. One of these characteristics is the number of valence electrons, or the electrons on the outermost orbit of an atom. So, any element within the same group will have the same number of valence electrons, which will then lead to other shared characteristics, such as chemical properties (how an atom reacts during a chemical reaction, for example).
