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俄国化学家门捷列夫在总结前人经验的基础上,通过艰辛的努力,终于提出了现代元素周期表的雏形。下表为元素周期表的部分示意图,表中数字为各元素原子的质子数,利用下表回答相关问题: (1)用符号表示:带两个单位负电荷且质子数为8的离子 (写一种)。 AB 2 型化合物 (写一种)。 (2)去年底重庆开县发生天然气“井喷”事件。喷出的气体中有一种有毒的含有18个质子的A 2 B型气体,其水溶液是一种无氧酸,请用符号和数字表示:3个A 2 B分子 。 (3)研究表中各元素原子的质子数,可发现元素从的排列规律是 ,请预测质子数为20的元素在表中的位置 (填①. ②. ③)。该元素离子的结构示意图是 。(填“甲”或“乙”)
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