题目

Chocolate is good for your heart, skin and brain．Usually, people think that chocolate is bad for their health．They describe chocolate as“something to die for”or say“death by chocolate”．Now they should bite their tongues! Evidence is showing that some kinds of chocolate are actually good for you in the following ways: A happier heart Scientists at Harvard University recently examined 136 studies on cocoa—the main ingredient in chocolate and found that it does seem to strengthen the heart．Studies have shown heart benefits from increased blood flow．These benefits are the resul有A、B、D、E、F、G六种前四周期的元素，A是宇宙中最丰富的元素，B和D的原子都有1个未成对电子，B＋比D少一个电子层，D原子得一个电子填入3p轨道后，3p轨道全充满；E原子的2p轨道中有3个未成对电子， F的最高化合价和最低化合价的代数和为4。R是由B、F两元素形成的离子化合物，其中B＋与F2－离子数之比为2∶1。G位于周期表第6纵行且是六种元素中原子序数最大的。请回答下列问题：(1)D元素的电负性_______F元素的电负性（填“＞”、“＜”或“＝”）。(2)G的价电子排布图_________________________________。(3)B形成的晶体堆积方式为________，区分晶体和非晶体最可靠的科学方法是对固体进行_______实验。(4)D－的最外层共有______种不同运动状态的电子,有___种能量不同的电子。F2D2广泛用于橡胶工业,各原子均满足八电子稳定结构,F2D2中F原子的杂化类型是___________,F2D2是______分子（填“极性”或“非极性”）。(5)A与E形成的最简单化合物分子空间构型为_____，在水中溶解度很大。该分子是极性分子的原因是_____。(6)R的晶胞如图所示，设F2－半径为r1 cm，B＋半径为r2cm。试计算R晶体的密度为______。（阿伏加德罗常数用NA表示，写表达式，不化简）