一、利用元素在周期表中特殊位置确定 此类类型最为简单,一般只需记住一些周期表中特殊位置的元素即可,现总结归纳如下10条,以供参考. 1.族序数等于周期数的元素:H、Be、Al. 2.族序数等于周期数2倍的元素:C、S. 3.族序数等于周期数3倍的元素:O. 4.周期数是族序数2倍的元素:Li. 5.周期数是族序数3倍的元素:Na. First, the use of elements in the periodic table to determine this type of special place is the most simple, generally only need to remember some elements of the special position of the periodic table can be summed up as follows 10 for reference. 1. Family number equals period The number of elements: H, Be, Al. 2. The element whose number is equal to twice the number of cycles: C, S. 3. The element whose number is 3 times the number of cycles: O. 4. The number of cycles is 2 times the number of elements. Element: Li. 5. The number of cycles is three times the number of elements: Na.