A compound of this element can react with an alkene in an anti-Markovnikov fashion.
An atom of this element is bonded to nitrogen and oxygen in the CBS catalyst. Like carbonium, compounds of this element often exhibit 3-center-2-electron bonds. A mineral of this element forms cross-links between polyvinyl alcohols found in certain glues to form a slime-like polymer. A compound of this element can react with an alkene in an anti-Markovnikov fashion. Found in Pyrex glass, this element is used to dope p-type silicon and forms trigonal planar trihalides, common examples of Lewis acids. Somewhat stable with only 6 valence electrons, it is an exception to the octet rule. For 10 points, name this fifth element with symbol B.
An atom of this element is bonded to nitrogen and oxygen in the CBS catalyst.
{boron} [accept {B} until mentioned]