createNode( 'Elements', 'Elements' ); $tree->setRootNode( $rootNode ); $nonMetal = $tree->createNode( 'NonMetals', 'Non-Metals' ); $rootNode->addChild( $nonMetal ); $nobleGasses = $tree->createNode( 'NobleGasses', 'Noble Gasses' ); $rootNode->addChild( $nobleGasses ); $nonMetal->addChild( $tree->createNode( 'H', 'Hydrogen' ) ); $nonMetal->addChild( $tree->createNode( 'C', 'Carbon' ) ); $nonMetal->addChild( $tree->createNode( 'N', 'Nitrogen' ) ); $nonMetal->addChild( $tree->createNode( 'O', 'Oxygen' ) ); $nonMetal->addChild( $tree->createNode( 'P', 'Phosphorus' ) ); $nonMetal->addChild( $tree->createNode( 'S', 'Sulfur' ) ); $nonMetal->addChild( $tree->createNode( 'Se', 'Selenium' ) ); $nobleGasses->addChild( $tree->createNode( 'F', 'Fluorine' ) ); $nobleGasses->addChild( $tree->createNode( 'Cl', 'Chlorine' ) ); $nobleGasses->addChild( $tree->createNode( 'Br', 'Bromine' ) ); $nobleGasses->addChild( $tree->createNode( 'I', 'Iodine' ) ); ?>