So say my queen is pinned in front of my king by the opponents rook. However if I move my queen to check their king it is certain checkmate, is that legal? I'm not sure because I'm intentionally endangering my king to be taken on the next move, but technically there won't be a next move since I checkmate my opponent.
Think of it this way:
Check mate is where nothing the opponent can do will save them from having you take their king on the next turn, so even if by putting their king in checkmate, you expose your own king, they can take your king before you can take theirs.
There is NO circumstance in which your actions put your own king into check without an opponent making a move.
The rules are clear. A move that puts your king in check is an illegal move (I'll leave it to you to find the reference; you might find the other rules helpful to review once you get there).
You cannot checkmate your opponent's king (or accomplish anything else) with an illegal move. Once you make an illegal move on the board, the following things happen:
- The position is restored to the position in effect before the illegal move is made.
- You get penalized for an illegal move. For the 1st and 2nd offenses, this results in your opponent's being awarded an extra 2 minutes on his clock. For the 3rd offense, the normal penalty is forfeit of the game.
Nice try, though.
Basically if you are confused about pin/checkmate rule, just play the game out until one king is captured.
You move you Q to threat taking his king in your NEXT move. Unfortunately it's now his move and he takes your K first.
On the other hand, if you use your other piece to attack so that his K has to move into your pinned Q's firing range, you can capture (not threat to capture) his K with your Q before he can capture your K. Or in standard chess rule, he is checkmated.
Official chess rules by FIDE
Rule 3.9 is as follows:
3.9 The king is said to be 'in check' if it is attacked by one or more of the opponent's pieces, even if such pieces are constrained from moving to that square because they would then leave or place their own king in check. No piece can be moved that will either expose the king of the same colour to check or leave that king in check.