in this video i'll be explaining the function and purpose of the following accidentals sharps flats naturals double sharps and double flats i will also be explaining what are semitones and tones or half steps and whole steps as they are also known the first thing to clarify is where to place the accidentals on the stave this note is a if i wanted to change it to a sharp i place the sharp symbol before it it's never correct to put the accidental after the note i appreciate that we may say sharp after the note name such as a sharp but it's the same as saying 12 pounds or 12 the word pound or dollar comes after the value if we wrote this not only would it look odd it would be wrong the symbol sharp or flat or natural always comes first you also need to ensure that the accidental sits neatly next to the note this would be wrong the flat symbol has been placed too high here the sharp has been placed too low the sharp has been written way too big here it's very important that when writing accidentals you are very clear which notes they are attached to make sure that the middle of the sharp or flat sits on the same line or in the same space as the note head like this one signatures are different to accidentals a key signature like this ensures that all of the fs and c's in the piece are played as f sharps and c sharps this is f sharp so is this and so is this accidentals however only last for a bar and only affect the line or space in which they sit therefore here's a bar of music each of the notes are b's if i add a flat to the first note it becomes b-flat the second note would also become b-flat as it is in the same bar there's no need to put another flat symbol however the final note stays a b it does not become b flat as it does not sit on the same line or space as the accidental now it's easy to forget this rule so sometimes but not always a piece of music may put an accidental in brackets to remind you of the correct note to play if i did want the second note to remain a b and not a b flat this is where i would use a natural symbol the natural symbol means cancel any previous accidental in the bar which may affect this note so just so we're certain on this rule here's another piece of music we'll go through each note one by one the first note is c the key signature doesn't affect the note and it has no accidentals attached to it the second note is b the natural symbol is cancelling the b flat from the key signature the third note is a g the next note is a b flat not a b natural although there is an accidental on the second note making it a b natural instead of b flat because that accidental only affects the same line this note is not affected the next note is an a flat a flat due to the key signature the next note should be an e flat due to the key signature but the natural symbol makes it e this note is e flat due to the key signature the accidental on the previous note does not affect this note because it is not sharing the same line or space this is an f and the final note is a b not a b flat the accidental on the b earlier in the bar will affect this note to explain the definition of accidentals you need to be absolutely clear about semitones and tones now semitones and tones are also known as half steps and whole steps either term is correct but for simplicity i'm going to stick with semitones and tones for the rest of this video to explain semitones and tones we'll use a keyboard firstly it's important to notice which notes are neighbors on the keyboard for example c is next to c-sharp or d-flat c is not next to d there may seem to be next to each other but this note c-sharp d-flat is between them just try and imagine the black notes extending all the way down to the bottom of the keyboard to work out which notes are neighbors when notes are neighbors to each other they are referred to as a semitone apart so c to c-sharp or d-flat is a semitone c-sharp or d-flat to d is also a semitone e to f is also a semitone as there is no black note between them so remember that notes have to be neighbors to be considered a semitone apart if two notes are two semitones apart we refer to them as a tone apart therefore we could say that c is a tone away from d because there is one semitone from the c to the c sharp or d flat and then another semitone from the c sharp or d flat to the d so just one final example how far is d sharp from f here's the d sharp it's one semitone to e and then another semitone to f as we've counted two semitones the distance from d sharp to f it could be described as a tone apart so remember a tone is made up of two semitones whereas a semitone are two neighbouring or adjacent is probably the better word notes on the keyboard don't forget to carefully count those black notes when you are working out tones and semitones it's really important to understand the purpose of semitones and tones as accidentals are directly related to them a sharp symbol raises a note by a semitone in other words you move up the keyboard by one semitone and when i say up i mean further up the keyboard towards the highest sounding notes in the direction of this arrow so for example here's c and i've marked it on the keyboard as well putting a sharp symbol in front of it makes it c sharp one semitone higher a flat symbol lowers a note by a semitone in other words you move down the keyboard by one semitone and when i say down i mean further down the keyboard towards the lowest sounding notes in the direction of this arrow so here's d and here it is on the keyboard putting a flat in front of the note makes it d flat one semitone lower you will have noticed that c sharp and d flat are exactly the same note on the piano now there's a very complicated reason for this something which i won't go into in this video however just be aware that the note at the bottom of the screen is d flat even though it shares the same note on the keyboard it is never correct to call it c sharp similarly the second note is c sharp it would never be correct to call it d flat if you are interested when a note has two or more names it is called an n harmonic equivalent so we can say that c sharp is the n harmonic equivalent of d flat a quirky music is the use of double sharps and double flats let's look at double sharps first it looks like a little x i've already said that a sharp raises a note by a semitone well a double sharp raises a note by two semitones or a tone if you prefer so this is g and here it is marked on the keyboard if we place a double sharp next to the note g it will be raised by two semitones and will be called g double sharp looking at the keyboard we can see that by raising the g by two semitones takes us to a therefore although the note is written g double sharp you'd actually play an a it's never correct to call it a this note is g double sharp but you could say that a is the n harmonic equivalent of g double sharp now you might be wondering what on earth the point of writing a g double sharp is why not just write an a this is a very good question but outside the scope of this video if you haven't already done so have a look at my videos on minor scales which tackles this very issue a double flat lowers a note by two semitones or a tone it looks like two flat symbols pushed close together so this is b and here it is marked on the keyboard if we place a double flat symbol next to the b it will be lowered by two semitones and will be called b double flat looking at the keyboard we can see that by lowering the b by two semitones takes us to a therefore although the note is written b double flat you'd actually play an a and remember it's never correct call this note a the note is b double flat just like other accidentals we've looked at in this video sharps flats and naturals double sharps and flats only apply for a bar and only affect the line or space in which they sit therefore have a look at this bar see if you can name all of the notes feel free to pause this video for as long as you need i'll go through the answers in a moment the first note is c the key signature doesn't affect the note and it has no accidentals attached to it the second note is b the natural symbol is cancelling the b flat from the key signature the third note is a double sharp the next note is b flat although there is an accidental on the second note making that note a b natural instead of b flat because that accidental only affects the same line this note is not affected the next note is a flat a flat due to the key signature the previous double sharp on the a does not affect this note as it is not in the same space or sharing the same line the next note is e double flat this note is e flat due to the key signature the accidental on the previous note does not affect this note because this is not sharing the same line or space this is an f and the final note is b not b flat the accidental on the b earlier in the bar will affect this note i do hope that this video has been useful to you please do drop me a line if you'd like to cover any other music theory topic and thanks for watching