AP BIOLOGY

Detailed explanation-1: -The vertical columns on the periodic table are called groups or families because of their similar chemical behavior. All the members of a family of elements have the same number of valence electrons and similar chemical properties. The horizontal rows on the periodic table are called periods.

Detailed explanation-2: -The vertical columns (groups) of the periodic table are arranged such that all its elements have the same number of valence electrons. All elements within a certain group thus share similar properties.

Detailed explanation-3: -The periodic table is composed of vertical columns called groups and horizontal rows called periods. The periodic table is divided into groups (vertical columns) and periods (horizontal rows).

Detailed explanation-4: -An element family is a column of elements on the periodic table. Each member of a family has the same number of valence electrons. Family members share similar chemical and physical properties. An element family is also called an element group.

Detailed explanation-5: -The s-, p-, and d-block elements of the periodic table are arranged into 18 numbered columns, or groups. The elements in each group have the same number of valence electrons.