文明史的划分,一般认为始于铁器时代,铁之所以作为支撑人类文明的材料被广泛地应用,因为铁有7种特性: 1.虽然铁的原子序数高,但大量存在 在整个宇宙中铁元素的贮量位于第8,前7位的原子序数都在14号以内,而铁一下子跳到26号。原子序数比铁高的物质,在宇宙中的百分含量都远低于铁含量。此外,整个地球的32％是铁,高于占30％的氧,为第10位,可以把地球叫做铁星。在地壳 The classification of the history of civilization, generally believed that began in the iron age, the reason why iron as a material supporting human civilization is widely used, because iron has seven characteristics: 1. Although the atomic number of iron is high, but a large number exist in the entire universe of iron Of the reserves in the first 8, the first seven atomic numbers are within the 14th, while the iron suddenly jumped to the 26th. Substance of atomic number higher than iron, the percentage of the universe are far below the iron content. In addition, 32% of the entire earth is iron, which is higher than 30% of oxygen. For the tenth place, the earth can be called an iron star. In the crust