Nature, most elements have two or more isotopes, the same kinds of elements in the quality of the various isotopes of different, but the types and proportion constant (except for radioactive elements). In 1961, the carbon content of the most abundant in nature, a kind of isotope, carbon-12 atom of a quantity and quality of C as a 12 mass units to it as "benchmarks" for all isotopes of an element according to the average abundance The ratio of the benchmark is the atomic weight of this non-prime, that is listed in the periodic table of atomic weights.

自然界中大多數(shù)元素都有兩種或更多的同位素业余处女视频网站，同種元素的各同位素質(zhì)量不同，但其種類和比例是恒定的。1961年，把碳在自然界含量最豐富的一種同位素日韩午夜精品福利久久，碳12的一個原子的質(zhì)C量定為12個質(zhì)量單位，把它作為"基準(zhǔn)"欧美精品一区二区福利视频一区，某種元素的所有同位素按豐度的平均值與基準(zhǔn)之比性欧美69式XXXXX，就是這種無素的原子量，即元素周期表列出的原子量国产色在线观看手机在线观看。

Atomic number Z = 25, atomic weight of 54938, the chemical symbol Mn, only the F there is a stable isotope, radioactive short-lived, there are three kinds of allotrope α,β,γ.

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Products Introduction: Silicon cycle, the department of the first type IV elements, is a non-metallic element, atomic number 14, atomic weight 28.80; density of 2.33g/m3; melting point of 1410 ℃; boiling point of 2355 ℃; resistively for 2140Ω.M; includes two types of stereotypes and crystal allotrope.

硅周期系第 IV 類元素黄色网站免费看入口，是非金屬元素，原子序數(shù)14色多多在线观看网址，原子量為28.80国产婬乱a一级毛片多女；密度為2.33g /m3；熔點(diǎn)為1410℃一级毛片免费视频网站；沸點(diǎn)為2355℃毛片网址站；電阻率為2140Ω。m 精品黄色网站一级；有無定型和晶體兩種同素異形體国产一区二区免费A片。

The atomic weight of an element that has the same combining capacity as a given weight of another element ; the standard is 8 for oxygen

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Molecular weight is expressed in the same unit as atomic weight .

分子的重量和原子的重量用相同的單位表示摸一摸AV。

For each substance, a mole is its atomic weight, molecular weight, or formula weight in grams.

對于每種物質(zhì)來說，莫耳是它以克為單位的原子量黄色A片免费看一级、分子量或式量免费裸体黄网站。

For example, H, atomic weight of 100,794 hydrogen, carbon FC atomic weight of 1201, the atomic weight of oxygen O for 1594, Copper Cu for F63546 and so on. F history, had also used the other two kinds of "benchmarks", and there have been two kinds of scales used in parallel .1803 years, J Dalton published the first atomic table, the hydrogen-quality of the original F son as a "benchmark "requiring H, atomic weight is 1. In 1826, JJ Berzelius Tony F are presented to the quality of 116 oxygen atoms O as a" baseline "(scheduled for O, E atomic weight 16), which is has been in use to 1961 "Oxygen unit." 1929, found that the oxygen in nature, in addition to the greatest abundance of 16O, there are a small amount of slightly heavier 17O and 18O two kinds of isotopes, and the different sources of oxygen, its composition is slightly different.

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Group in periodic table with silver-white metallic luster of the solid metal transition elements, but also one of the platinum group element, atomic number Z = 44, atomic weight of 10107, the chemical symbol F No.

周期表中Ⅷ族銀白色具金屬光澤的固體金屬過渡元素www.麻豆精品，又是鉑系元素之一，原子序數(shù)Z＝44免费观看A级毛片在线网站，原子量10107自拍偷拍欧美，化學(xué)符F號Ru。

Group in the periodic table there are silver-white metallic luster of the solid metal transition element, atomic number Z = 26, atomic weight of 55847, chemical symbol Fe, there is a stable F isotope 5626Fe and a radioisotope 5526Fe, content of 5% of the earth's crust, accounting for elements of in the fourth place, the metal in the second melting point 1535 ℃, boiling point 2750 ℃, the relative density of 786, the external electronic structure 3d64s2, chemical reactions 2-6 tram F-volatile son, oxidation number of 0, 2, 3, 4 , 5 and 6, the chemical nature of the metal element is very lively, in the humid air combined with oxidation, but also directly with the sulfur, phosphorus, silicon, carbon together.

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Periodic Table Ⅵ B family silver-white metallic luster of the solid metal transition element, atomic number Z = 74, atomic weight of 18385, chemical symbol W, there are five kinds of natural F stable isotopes, 18174W, 18274W, 18374W, 18474W, 18574W and eight kinds of radioisotopes .

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