To find the number of students in the Environmental Club, we can calculate 20% of the total number of students in the seventh grade, which is 180.
First, we convert the percentage to a decimal by dividing by 100:
\[ 20% = \frac{20}{100} = 0.20 \]
Next, we multiply this decimal by the total number of students:
\[ \text{Number of students in the Environmental Club} = 0.20 \times 180 \]
Calculating this:
\[ 0.20 \times 180 = 36 \]
Therefore, the number of students in the Environmental Club is \(\boxed{36}\).