Happy Valentine's Day! Whether you've got a hot date or you're hanging with your friends and family, it's the perfect day to stop and smell the roses.

But what exactly gives roses their sweet smell anyway? Just check out the latest video (above) from the American Chemical Society's Reactions series.

According to the video, there are thousands of rose species, and many of them don't smell at all--but that classic rose scent used in perfumes and lotions comes from a particularly fragrant species called the Damask rose.

Several chemicals, including a compound called rose oxide, contribute to the signature smell. Rose oxide comes in four kinds, which produce sweet, fruity, mint and citrus scents -- and they contain the same atoms, but they're arranged differently in space, which means they interact differently with the receptors in our noses.

"Chemistry is full of these subtle differences," Dr. Raychelle Burks, a chemist at Doane College in Crete, Nebraska and social media maven, says in the video. "Arranging atoms even slightly differently can mean that a rose by any other configuration doesn't smell as sweet."