To compare the numbers \(5 \times 10^{-11}\) and \(3 \times 10^{-11}\), we can look at their coefficients since they have the same exponent.
Here, \(5\) is greater than \(3\).
Thus, the correct symbol to place in the blank is \(>\).
So, the statement reads:
\(5 \times 10^{-11} > 3 \times 10^{-11}\)