Which chemical bond is broken when hair is permed?

When hair is permed, the primary focus is on changing the hair's structure to achieve a desired curl or wave. This transformation is largely due to the breaking and reforming of specific types of bonds within the hair's protein structure. The correct choice, disulfide bonds, refers to the strong covalent bonds that form between the sulfur atoms in the amino acid cysteine, which contribute significantly to the hair's strength and shape.

During the perming process, a chemical solution is applied that breaks these disulfide bonds, allowing the hair to be reshaped around rods or curlers. Once the hair is set in the new shape and a neutralizing solution is applied, new disulfide bonds are formed, solidifying the hair's new curl pattern. This process highlights the importance of disulfide bonds in the structural integrity and styling of hair.

Other types of bonds mentioned, such as hydrogen bonds and ionic bonds, play roles in hair's physical properties but are not responsible for the permanent change achieved in a perm. Hydrogen bonds are weaker and can be easily broken by water or heat, while ionic bonds also do not contribute to the long-lasting structural change that perms create. Thus, disulfide bonds are the key bonds that are specifically