Introduction to Chirality

If you found a hand on the side of the road, you’d instantly know if it was a left or right hand. This simple recognition is known as handedness, or chirality, and it reveals a fundamental truth: the world is chiral, and so are we. Our bodies are built from chiral molecules, and to interact effectively, many of our medicines must be chiral as well. In drug development, even the smallest structural difference can mean the difference between healing and harm. Chirality isn’t just a chemical curiosity—it’s essential to life itself.

Take Note
  • Chirality means handedness.  Just like we have right and left hands, we can have right and left-handed molecules!  We call them R and S instead of left and right.
  • The mirror image of a left hand is a right hand!
Action
  • Consider the two mirror image molecules below.  The mirror plane is perpendicular to your screen.
  • Rotate the molecule on the left by clicking down and moving your mouse.  Notice how the mirror image on the right moves, much like your hand when waving in a mirror.
  • Mirror images of chiral molecules are non-superimposable.  Non-superimposable means they do not occupy the same space if you attempted to lay on top of the one other.  Trying to make it fit is like forcing a left-handed glove onto a right hand – it’ll never match!

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