Boron nitride (BN) exists in two forms. The first is a slippery solid formed from the reaction of BCl3 with NH3, followed by heating in an ammonia atmosphere at Subjecting the first form of BN to a pressure of 85,000 atm at produces a second form that is the second hardest substance known. Both forms of BN remain solids to Suggest structures for the two forms of BN.
CHAPTER6:COMPOUNDS Twoormoreelementscombinedchemicallyina fixedratio IONICCOMPOUNDS:MAKEIONSOFATOMSANDUSE ELECTROSTATICATTRACTION v Positiveions:usuallyoccurwithinallmetals(solids)intheperiodictable. Ø Metalsareabletoremoveanelectronfromthereoutmostshells (valenceelectrons) Ø Ø IONSIZEDECREASESACROSSTHETABLE,THEREFOREPOSTIVIE IONSIZESARESMALLERTHANATOMS v Negativeions:non-metals Ø NonMetalsgainelectrons,makingtheionnegative Ø Ø Repulsionisgreaterthanattraction,soNEGATIVEIONSGETBIGGER (sizewise)ACROSSTH