Question

What is meant by "the energy of an electron is quantized"?

Answer 1

this is a difficult concept to explain, in general, it means the amount cannot be any arbitrary amount and that it can only be a multiple of some minimum nonzero amount.

Answer 2

Another way to say it is that the energy comes in packets.

Answer 3

Well, sure. That's a very basic explanation that doesn't really explain mathematics behind it.

Answer 4

If they're looking for the total explanation I'd suggest Google or chemistry/physics books.

Answer 5

The energy is quantized in certain circumstances, such as in or from atomic shells, but can be continuous, such as for free electrons.