Why do whole numbers get raised to an exponent get greater, while fractions raised to an exponent get smaller

Because a whole number raised to a power means

                     several times several ,

but a fraction raised to a power means

                       a piece of a piece .

Actually, not all fractions when raised to an exponent get smaller.  For example, .  9/4 is bigger than 3/2, so this fraction gets bigger when raised to an exponent.

In reality, positive numbers less than one decrease when raised to an exponent, and numbers greater than one increase. Multiplying a positive number by any number greater than one increases it's value, and multiplying it by any number less than one decreases it's value.  For numbers less than one, taking the exponent involves multiplying it by a number less than one, thus decreasing it, and for numbers greater than one, taking the exponent involves multiplying it by a number greater than one, thus increasing it.