how many main energy level are in there in the periodic table?(refer to periodic table,the number on the left side of the periodic table.)​

7 energy levels:

Explanation:

The periodic table is organized into columns and rows. The number of protons in the nucleus increases when reading the periodic table from right to left. Each row represents an energy level. The elements in each column share similar properties and the same number of valence electrons. Valence electrons are the number of electrons in the outermost energy level.

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