Elements in the first column all have one electron in their outermost shell. Those in the second column have two outer electrons, and so on.
第一列元素最外电子层内均有一个电子，第二列元素则含有两个电子，依此类推。
Elements in the first column all have one electron in their outermost shell. Those in the second column have two outer electrons, and so on.
第一列元素最外电子层内均有一个电子，第二列元素则含有两个电子，依此类推。
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