Period (periodic table) facts for kids

A period in the periodic table is like a horizontal row of elements. Think of the periodic table as a big chart that organizes all the known chemical elements. Each row helps us understand how elements change as their atomic numbers increase.

The elements in a period are arranged by their atomic numbers, which means the number of protons in their atoms. As you move from left to right across a period, the atomic number goes up by one for each element.

Elements on the left side of a period are usually very metallic, like sodium or calcium. As you move to the right, the elements become less metallic and more nonmetallic, like oxygen or chlorine.

The first period has only 2 elements. The second and third periods each have 8 elements. The fourth and fifth periods each have 18 elements. The sixth and seventh periods each have 32 elements because they include the special f-block elements.

The Periodic Table Periods

Here is the standard periodic table, showing how elements are organized into periods and groups.

Chemical Series of the Periodic Table

This section explains the different types of elements you see in the table, based on their properties and where they are located.

State at standard temperature and pressure

The color of the number (atomic number) above the element symbol shows what state the element is in at normal room temperature and pressure.

• those in blue are gases
• those in green are liquids
• those in black are solid

Images for kids

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  From left to right, aqueous solutions of: Co(NO3)2 (red); K2Cr2O7 (orange); K2CrO4 (yellow); NiCl2 (green); CuSO4 (blue); KMnO4 (purple).