Propagation Step:Carbon Radical First propagation step H CH H-CI H H methane chlorine atom methyl radical hydrogen chloride Copyright2010 Pearson Prentice Hall,Inc. The chlorine atom collides with a methane molecule and abstracts (removes)an H, forming another free radical and one of the products (HCI). Chapter 4 6 Chapter 4 6 Propagation Step: Carbon Radical The chlorine atom collides with a methane molecule and abstracts (removes) an H, forming another free radical and one of the products (HCl)