The Periodic Table: Families and Periods. In the periodic table of elements, there are seven horizontal rows of elements called periods. The vertical columns of elements are called groups, or families.

Yes it's universal Chemistry truth....there are totally 7 horizontal rows are there they are called as periods and the vertical columns are called as group or families... so the option D is correct...hope u clear...!👍

Explanation:


The periodic table is a tabular arrangement of the chemical elements. It is organized in rows and columns according to the electron configurations of the elements. The horizontal rows in the periodic table are called periods. There are seven periods in the periodic table, numbered from 1 to 7. Each period represents a different energy level of the elements in that row. The elements in each period have the same number of electron shells.


Characteristics of periods:

• Elements in the same period have the same number of electron shells


• Elements in the same period have different numbers of electrons in their outermost shell


• The number of elements in each period varies


• The properties of the elements in each period change gradually as you move across the table from left to right

Examples:


Period 1 contains only two elements: hydrogen and helium. Both have one electron shell.


Period 2 contains eight elements: lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. All these elements have two electron shells.


Period 3 contains eight elements: sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, and argon. All these elements have three electron shells.


Conclusion:


In conclusion, the horizontal rows in the periodic table are called periods. There are seven periods in the periodic table, and each period represents a different energy level of the elements in that row. The elements in each period have the same number of electron shells, and their properties change gradually as you move across the table from left to right.