 To designate two anomers the relative stereodescriptors alpha (α) and beta (β) are used.In the α anomer the "anomeric carbon atom" and the "reference atom" do have opposite configurations ("R","S") or ("S","R"), whereas in the β anomer they are the same ("R","R") or ("S","S").Stereochemistry also plays a role assigning "faces" to trigonal molecules such as ketones.