The main idea of a chromatic scale is the twelve tones in the chromatic scale, the construction would look like so 1,2,3,4,5,6,7,8,9,10,11,12,1 (1 starts it over again)
Whole steps would be skiping a tone or scale degree such as 1 to 3 in the above(cromatic scale).
While a half step would be 1 to 2. I say this because we are now switching from the the 12 tone chromatic scale to the seven of the major scale.
Tetra chord-basically half of a major scale. 1,2,3,4 would be the first tetra chord or half while 5,6,7,8/1 would make the scale complete, being its the second half.(8/1 because 8 and 1 are the same note but 8 would be the note directly after 7, as 1 would be the first note you played.)
Note there are more tetra chords that one, this is just what were dealing with.
The universal scale degrees same amout of digits/step as the chromatic scale, with different symbols 1,_,2,_,3,4,_,5,_,6,_,7,1(these _,_,_,_ represent shrarps and flats/ 1,_,2 here _ equals 1# and 2flat notice it means two different notes but only takes one step/digit).
The major scale which you have probably heard, looks like so DO RE MIFA SO LA TIDO(MI and FA/TI and DO are two different tones but instead of a whole step theirs only a half step)where a space is located=whole step.
Notice there are twelve steps, ex- 1.DO 2.space 3.RE 4.space 5.MI 6.FA 7.space 8.SO 9.space 10.LA 11.space 12.DO
Can you point out the tertra chords there a pattern huh?
Looking at you fret board you could see
The C Major scale consists of these notes C D EF G A BC(1=C,2=D,3=E,4=F this pattern C D EF which would make the first tetra chord along with G A BC/5,_,6,_,7,1 this maks up the C major scale. Every major scale contains two tetra chords.
Notice that the first note of the second tetra chord is the fith note.
By the way a whole step on you guitar is skiping a fret.