Identify the word that means vertical columns of Periodic Table.

Groups

The correct answer is option 2. Groups.

Groups, also known as families, are the vertical columns in the periodic table. 

The periodic table is organized into rows and columns. The vertical columns represent groups of elements with similar chemical properties. Each group contains elements that have the same number of valence electrons in their outermost shell.

Elements within the same group tend to exhibit similar chemical behavior due to their identical valence electron configurations. This similarity arises because elements in the same group have the same number of electrons in their outermost energy level, which determines their chemical reactivity and bonding characteristics.

Groups are often numbered from 1 to 18, starting from the left-hand side of the periodic table. Some periodic tables also use a different numbering system, such as the IUPAC (International Union of Pure and Applied Chemistry) numbering system, which labels groups from 1 to 18 or uses a combination of letters and numbers.

Each group in the periodic table has its own characteristic properties. For example, Group 1 elements (alkali metals) are highly reactive metals that readily lose their outermost electron to form positively charged ions. Group 18 elements (noble gases) are generally inert and unreactive due to their stable electronic configurations.

In summary, groups in the periodic table are the vertical columns that contain elements with similar chemical properties, determined by the number of valence electrons they possess.