三硝酸盐

Melting point 3410 ℃, boiling point 560 ℃, relative density of 1935, F the external electronic structure of 5d46s2, in the chemical reaction time is very easy to lose 1-6 electronic, but also can get 1-2 electronic, so oxidation number of 0,± 1,± 2, 3, 4 , 5 and 6, with 6 price of the most stable compounds, such as WO3 does not dissolve in water, the air will form in the tungsten trioxide thin protective layer of tungsten, tungsten with fluorine at room temperature, chemical combination, red hot when there is no moisture and Bromine iodide together, red hot when you can and water reaction WO3, at room temperature reaction of tungsten with aqua regia, but the hot concentrated hydrochloric acid and sulfuric acid can only be played with its weak response, but molten nitrate, nitrite, too Hydrogen peroxide, sulfur steam, steam and other phosphorus can play intense reaction, high temperature can not be carbon, boron and silicon reaction of binary compounds, widely used in industrial tungsten steel and tungsten carbide, pure tungsten filament is used to the system, and X-ray tube Tube heating components, semiconductor components can be prepared tungsten silicide, tungsten industrial production is white or black tungsten ore tungsten ore refining.

熔点3410℃，沸点560℃，相对密度1935，F外围电子结构为5d46s2，在化学反应时很容易丢掉1—6个电子，也能得到1—2个电子，所以氧化数为0、±1、±2、＋3、＋4、＋5和＋6，以＋6价化合物最稳定，如WO3不溶于水，空气中的钨会形成薄层三氧化钨保护层，钨能与氟在室温下化合，红热并无潮气时能与溴、碘化合，红热时还能和水反应生成WO3，室温下钨可与王水反应，但热的浓盐酸和硫酸只能与其起微弱反应，但对熔融的硝酸盐、亚硝酸盐、过氧化氢、硫蒸汽、磷蒸汽等能起激烈反应，高温下不能与碳、硼和硅反应生成二元化合物，工业上广泛使用钨钢和碳化钨，纯钨用来制灯丝、电子管和X射线管的发热元件，硅化钨可制半导体元件，钨工业生产是将白钨矿石或黑钨矿石精炼。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。