元素在不同自然体系的分布:偶数规则之后,还有一个普遍规律——以类地行星为例

在地球化学、天体化学乃至宇宙化学领域中，有一个应用十分广泛的著名的偶数规则(即Oddo-Harkins规律)，该规律认为，元素在太阳系分布中，原子序数为偶数的元素丰度通常会比相邻的两个奇数元素丰度值高.通过研究发现，化学元素在宇宙不同自然体系中分布与分配，至少对非亲气元素而言，在统计上还呈周期性变化，而这种周期性变化恰好和元素周期律吻合.而偶数规则也和元素周期性变化规律存在着某种深刻的联系，实际上是同一地球化学现象不同侧面的反映.以地球和金星等自然体系的化学元素质量丰度的比值为例，说明任意两个自然体系，其形成与演化的历程、机制、程度、条件以及物质的来源和化学构成愈是接近，二者之间的元素比值的变化波形就愈符合元素周期律.定量地确定元素在自然体系中分布/分配曲线对元素周期性变化曲线的吻合程度.元素在自然体系分布上的元素周期性变化规律的发现及其量化描述的实现，为更科学地、精确地计算、校验和获取自然体系中化学元素的一些基础数据，提供了一个全新的思路. 

Distribution of Elements in Different Natural Systems:A General Rule after the Even Number Law,an Example of Terrestrial Planets

The even number law (that is,"Oddo-Harkins" law) holds that a given element with even atomic number is more abundant than both the adjacent elements with odd atomic numbers,which is widely-used in geochemistry,astrochemistry and even cosmochemistry. The present study shows that the distribution/allocation of chemical elements (at least for non-atmophile elements) in various natural systems also exhibits cyclical changes in statistics,which is well consistent with the "Periodic Law". In fact,there exists certain intrinsic relationship between the even number law and the cyclical changes stated in present study,and they just signature a same geochemical phenomenon from different angles. For two random natural systems (the Earth and Venus,for instance),the more similar the processes,mechanisms,stages and conditions of their formation and evolution,their material sources and chemical compositions are,the more consistent their variation waveforms of elemental abundance ratios are with the "Periodic Law". The matching degree between the distribution/allocation curve of elements in various natural systems and the periodic variation curve of these elements has been further determined. Overall,the discovery of cyclical changes of elemental distribution and its quantitative characterization provide a new perspective for calculating,checking and acquiring basic data on chemical elements in a natural system.