如表是元素周期表的一部分，请参照元素①〜⑦在表中的位置，请用化学用语回答下列问题：

（1）①〜⑦元素中原子半径最大的是　 ____　（用元素符号表示）；

（2）②、⑦两种元素所形成的气态氢化物中较稳定的是　 ____　（用化学式表示）；

（3）⑤、⑥两种元素最高价氧化物对应水化物的酸性较强的是　 ____（用化学式表示）

（4）写出③和⑥两种元素的最髙价氧化物对应水化物反应的离子方程式 ____

    Now a hot topic____(discuss) about whether the old computers in our school should be replaced____new ones. With the rapid____ ( develop) of science and technology, there is no doubt ____our old computers are totally out of date. The headmaster as well as the teachers and students____(be) not satisfied with the slow working speed of the computers. Therefore, all of them request to have a new computer so that their problems can be solved ____ （success).____the school should consider is ____to deal with the old computers wisely. Personally speaking,____(throw)  them away to the place____they are regarded as rubbish is not a good idea.

化合价指的是物质在形成化合物时表现出来的一种性质，所以，单质中元素的化合价为____ ；在化合物中，正负化合价的代数和为　____ ；在原子团中，正负化合价的代数和等于____