Compounds of this element and silicon were first isolated by Moissan and Stock. The selectrides are reducing agents containing this element, and cluster compounds of this element adopt closo, nido, or arachno configurations based on the number of electrons in the system. Reacting a compound of this 
Compounds of this element and silicon were first isolated by Moissan and Stock. The selectrides are reducing agents containing this element, and cluster compounds of this element adopt closo, nido, or arachno configurations based on the number of electrons in the system. Reacting a compound of this element with an alkene is a method of oxidizing the less substituted carbon in violation of Markovnikov's rule. This element's (*) triflouride is a powerful electron-deficient Lewis acid. Hydrides of this element tend to form 3 center two-electron bonds, and this element tends to violate the octet rule by having only 6 valence electrons. For 10 points, identify this element with atomic number 5 and symbol B.
Compounds of this element and silicon were first isolated by Moissan and Stock.
boron [or B before mention]