Scales are a particular arrangement of half steps and whole steps.
Major scales have the following pattern, where W= a whole step, and H= a half step:
W W H W W W H
Or half steps between the 3rd and 4th and the 7th and 8th scale degrees and whole steps between the other scale degrees. (A scale degree is the name used to describe each step of a scale).
If we look at the keyboard, we see that this pattern occurs naturally
from C to the next C.
There are half steps between E-F and between B-C, the 3rd and 4th steps and the 7th and 8th steps. There are no black keys between these notes.