How many elements can be there in the third period ?

Explanation

To determine how many elements can be in the third period of the periodic table, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Periodic Table Structure**: The periodic table is arranged in periods (rows) and groups (columns). Each period corresponds to the filling of electron shells.

2. **Identify the Third Period**: The third period includes elements that have their outermost electrons in the third shell (n=3).

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