How many electrons can occupy the 4p sub level of a neutral atom of bromine?

To help describe the appropriate notation for electron configuration, it is best to do so through example. For this example, we will use the iodine atom. There are two ways in which electron configuration can be written:

I: 1s22s22p63s23p64s23d104p65s24d105p5

or

I: [Kr]5s24d105p5