Chapter 15, Problem 8RQ

To determine

The number of periods in the periodic table.

Answer to Problem 8RQ

The number of periods in the periodic table is seven.

Explanation of Solution

When a material is made up of a single kind of a particular atom, then the material is called an element. There is a chart that lists all the known elements in the universe. This chart of elements is called the periodic table. This periodic table arranged the elements in a particular way in accordance with their properties.

There are vertical rows and horizontal columns in this table. The columns in the periodic tables are called groups. The horizontal rows are called periods. Across any period, the properties of elements gradually change. There are eighteen groups and seven periods in a periodic table.

Conclusion:

Therefore, the number of periods in the periodic table is seven.