The periodic system of D. I. Mendeleev establishes the laws of the dependence of the chemical properties of elements on their location. However, some elements may behave differently from physical and chemical processes than expected. A striking example is bismuth. Let us consider this metal in more detail, focusing on the question of the melting temperature of bismuth.
Chemical element bismuth
Looking at the periodic table, we can see that bismuth is denoted by the symbol Bi, has 83 number and atomic mass of 208.98 amu In the earth's crust, it is found in small amounts (8.5 * 10 -7 %) and is as rare as silver.
If we talk about the chemical properties of the element, it should be noted its inertness and difficulty in participating in reactions. The latter fact brings him closer to the group of noble metals. Externally, bismuth is a gray crystal with a pinkish tint. The greatest amount of this element is found in deposits in South America and the United States.
An element known since antiquity
Before considering the physical properties of bismuth and the melting temperature, it should be noted that the discovery of this element does not belong to anyone. Bismuth is among the 10 metals that have been known to man since ancient times, in particular, according to some indications, its compounds were used in ancient Egypt as cosmetics.
The origin of the word bismuth is not exactly known. The existing opinions of most experts are inclined to believe that it comes from the ancient German words Bismuth or Wismut, which means "white mass".
Since the melting points of bismuth and lead are very close to each other (271.4 ° C and 327.5 ° C, respectively), as well as the densities of these metals (9.78 g / cm 3 and 11.32 g / cm 3, respectively), then bismuth was constantly confused with lead, as well as with tin, which melts at a temperature of 231.9 ° C. Only in the middle of the 18th century did European chemical scientists demonstrate that bismuth is an independent metal.
Curious physical properties
Bismuth is an atypical metal. In addition to its chemical inertness and resistance to oxygen oxidation, it is a diamagnet, conducts heat and electric current poorly.
Even more curious is its transition from solid to liquid. As noted, the melting point of bismuth is lower than that for lead and is only 271.4 ° C. During melting, the volume of the metal decreases, that is, solid pieces of metal do not sink in its melt, but float on the surface. In this property, it resembles semiconductors such as gallium and silicon, as well as water.
No less surprising is the resistance of bismuth to radioactive decay. It is proved that any element of the table of D.I. Mendeleev, which is to the right of niobium (that is, has a sequence number greater than 41), is potentially unstable. Bismuth is located at number 83 and is the most stable heavy element, its half-life is estimated at 2 * 10 19 years. Due to its high density and high stability, it could replace lead protection in nuclear energy, but the rarity of bismuth in nature does not allow this.
Use of the element in human activity
Since bismuth is stable, chemically inert and non-toxic, it is used for the production of certain medications and cosmetics.
The similarity of the physical properties of the element to the characteristics of lead and tin allows it to be used as a substitute, since the last two metals are toxic. For example, Denmark, the Netherlands, the USA and many other countries have banned the use of lead as a filler in hunting shots, as birds, confusing it with small stones, swallow lead and experience subsequent poisoning. Technologies are also being developed for the production of bismuth sinkers for fishing in the place of lead.
Since the melting temperatures of tin and bismuth are close (the difference is only 40 ° C), often bismuth alloys with a low melting point are used as a substitute for toxic lead-tin solders, especially in the production of food packaging.
The challenge with a new temperature scale
In the course of physics, one can meet the problem of determining the melting temperature of bismuth on the Genius scale. We will say right away that this is just a task, and no genius scale exists. In physics, only three temperature scales are currently accepted: Celsius, Fahrenheit and Kelvin (in the SI system).
So, the conditions of the problem are as follows: "The new temperature scale, which is expressed in degrees of Genius (° G), is related to the Celsius scale as follows: 0 ° G = 127 ° C and 80 ° G = 255 ° C, it is necessary to determine the melting point of bismuth in degrees new scale. "
The challenge lies in the fact that the 1 ° G interval does not correspond to the 1 ° C interval. And what value does it correspond to in Celsius? Using the condition of the problem, we obtain: (255-127) / 80 = 1.6 ° C. This means that a 1 ° G increase in temperature will be equivalent to a 1.6 ° C increase. To solve the problem, we recall that bismuth melts at a temperature of 271.4 ° C, which is 16.4 ° C or 10.25 ° G higher than the temperature of 255 ° C (16.4 / 1.6). Since the temperature of 255 ° C corresponds to 80 ° G, we see that on the Genius scale, bismuth will melt at a temperature of 90.25 ° G (80 + 10.25).