Link to the full video below:
What is the difference between a Tone and a Semitone? For Grade 1 Theory at Trinity College, you need to know the following:
For a Tone:
If there is a black key in between two white keys on the piano, it is called a Tone. The same principle may apply for a white key skipped between two black keys.
For a Semitone:
If we move from a white key to the next adjacent black key, it is called a semitone.
If there is no black key between two white keys like between E and F and B and C, it is also called a semitone.
Remember to work out your notes using your rhymes or going stepwise should there be ledger lines involved. Mark the notes and use your piano drawing to determine whether it is a tone or semitone.