Do the chemicals in relaxers burn your hair and make it look dried out?

My mom said if I used relaxer in my hair, it would fry my hair. Would it??Do the chemicals in relaxers burn your hair and make it look dried out?
It will burn if you scratch you r head before you get the relaxer and your hair will look longer, softer and wavy. I always get perms/relaxers.Do the chemicals in relaxers burn your hair and make it look dried out?
any chemical is not good 4 your hair but if u have it done by as pro u dont need to worry