It’s perhaps still true that no one really expected musical innovation to come from a band put together on a reality TV show. However, as evidenced by hits like “Sound of the Underground” and their second album What Will the Neighbours Say?, Girls Aloud’s brilliance always lay in their anarchic ability to subvert expectations and their willingness to let the songs speak for themselves. As such, Chemistry feels like an apt title for the band’s third album: Much of the record feels like a strange experiment being led by a group of mad scientists. Those gathered around the Bunsen burner here are songwriting and production group Xenomania, who, together with Cheryl, Nicola, Kimberley, Nadine, and Sarah, appear to be conducting research into a new iteration of pop. Indeed, the tracks on Chemistry pretty much do away with traditional song structures and formulaic soundscapes to become mutant hybrid forms. On one song, you’ll encounter Gregorian chants, post-punk strumming, and laconic Betty Boo-style rapping (“Wild Horses”), only to a find bubbly beachside hip-swinger about cross-dressing boyfriends running down London’s Old Kent Road (“Long Hot Summer”) a few tracks later. In between, there’s a cover of Dee C. Lee’s “See the Day,” a lusty strutter about kinky one-night stands that references “strippers and the vicars” (“Watch Me Go”), man-hungry rock ’n’ roll (“Waiting”), and a ballad that could have been written by John Clifford Farrar (“Whole Lotta History”). It’s so wacky you might miss the album’s meta narrative about celebrity culture and cosmopolitan life as a young woman. The band pokes fun at sycophant fame hunters (“Models”), roll their eyes at terrible men (“Wild Horses”), and slip into the seductive hedonism and superficiality of city living on “Swinging London Town,” a propulsive song with aggressive action-movie beats and Giorgio Moroder synths that drop out completely for a watery and atmospheric bridge. It’s “Biology,” though, that crystallizes the album’s innovation. Comprised of discrepant and distinct sections, a number of tempo changes, and a sample from The Animals’ “Club-A-Go-Go,” it’s a bonkers concoction that reinvents the very molecular makeup of pop music. Never has science sounded so good.