【单选题】下列关于离子键的说法中正确的是
A.
离子键一定是在活泼金属和活泼非金属元素的原子之间才存在
B.
形成离子键时,离子间的静电作用指的是静电引力
【简答题】The bar-tailed godwit (斑尾鷸)has just broken its own record for the world’s longest non-stop flight, including humans in planes, according to a report made by Lund University Press. The bird can fly non...
【简答题】The bar-tailed godwit(斑尾鹬) has just broken its own record for the world’s longest non-stop flight, including humans in planes, according to a report made by Lund University Press. The bird can fly non...
【简答题】We'd like to take a non-stop flight,please.
【简答题】患者男性,20岁,因刀刺伤、昏迷40分钟急诊入院。入院时患者瞳孔散大,直径6mm,对光反应消失,血压测不到,右前胸壁有一长约10cm的伤口,有鲜血涌出。即刻在全麻下行开胸探查术,术中见心包右侧有一长约4cm的伤口,右心房有一长约3cm的破口,予以心房修补、右肺修补术,血压仍难以维持。继续探查,发现肝右叶脏面有一长约3cm的裂口,修补后血压逐渐上升并稳定,术后回ICU,呼吸机辅助呼吸。患者术后的护理...
【单选题】下列关于离子键的说法正确地是:
A.
当两种元素电负性差值>1.7时,形成化合物的化学键是离子键
B.
离子晶体中的离子键就是一个正离子和一个负离子之间的静电引力