Chemistry

The theme of this article is new materials derived from chemistry.

This article focuses on the question of "which rare metals are 'tough guys'" and introduces the definition of high-melting-point and corrosion-resistant metals, which are called "tough guys" among rare metals. It also lists the melting points, related characteristics, and application fields of metals such as tungsten, rhenium, osmium, tantalum, molybdenum, and hafnium.

This article focuses on answering the question "Are metals with low content in the crust rare metals?" It explains that the naming of rare metals is not only related to their content in the crust and their dispersed distribution, but also because they were discovered and applied in industry later than other metals. At the same time, it introduces the development history of rare metal extraction technology, the expansion of its application fields, and its future application prospects.

This article, titled "Why Are Rare Earth Elements Called the 'Vitamins' of Luminescent Materials?", introduces the definition of luminescent materials, the principle of luminescence, and the energy level structure and luminescent characteristics of rare earth ions. It explains that the 12 rare earth elements commonly used in luminescent materials correspond to the 12 vitamins needed by the human body, and the amount of rare earth doping is very small, hence the nickname. It also introduces the classification, functions, energy absorption forms, and extensive application fields of rare earth luminescent materials.

This article focuses on the question of "are rare earths soil?" and explains that rare earths are not ordinary soil, but a collective term for some metals that are difficult to dissolve in water. It introduces the origin of the name, the composition and electronic structure characteristics of rare earth elements, their physical and chemical properties, and the process of discovering all 17 rare earth elements over the past 150 years. It also explains the difficulty of discovering, producing, and separating rare earth elements, and takes promethium as an example to introduce its production method and occurrence in nature.

This article focuses on the question of "Is thousand-foot gold pure gold?" and introduces the ancient concept of pure gold and the belief that "no gold is pure", the modern gold purity measurement standard of K gold, the definition of gold content in pure gold and thousand-foot gold, and the standard of imprints. It clarifies that thousand-foot gold is not 100% pure gold, and also compares the purity difference between thousand-foot gold and monocrystalline silicon used in semiconductor manufacturing.

This article focuses on the question of "Will silver chopsticks turn black when they come into contact with poisonous food?" It explains that ancient silverware could detect poison because arsenic, a common poison in ancient times, often contained sulfur due to production process issues. Silver and sulfur would react chemically to form black and stable silver sulfide. It also uses the soft-hard acid-base theory to explain the stability of silver sulfide, and points out that silverware turning black over time is due to exposure to sulfur compounds in the air. However, using silverware to detect poison is not reliable nowadays, as many toxic substances do not contain sulfur, and sulfur-containing substances may not necessarily be toxic. Nowadays, there are more advanced scientific testing methods available.

The article "Is Real Gold Really Not Afraid of Fire?" cites the legend that gold utensils and jewelry melted into gold ingots after a fire in an ancient mansion and remained intact, to explain the saying "Real gold is not afraid of fire". It explains that gold is highly chemically inert and not easily reacted with other substances. Although its melting point is only 1064℃, it melts at high temperatures with little volatilization, almost no loss of mass, and unchanged color. It also introduces platinum (commonly known as white gold), which is more resistant to high temperatures and has more stable chemical properties, and meets the standard of "Real gold is not afraid of fire".

This article focuses on the question of "does stainless steel rust?" and introduces the process by which British metallurgist Henry Brearley accidentally discovered that steel with a chromium content of more than 12% is not easily rusted in 1913, and subsequently invented stainless steel. It also describes the promotion of stainless steel and its wide application in various fields, and demonstrates through experiments that stainless steel is not absolutely rust-free, but rather has strong resistance to rust.

This article focuses on the theme of "How Steel Is Tempered", introducing the intuitive impression of converter steelmaking, the raw materials and basic principles of steel production, the specific process of converter steelmaking, explaining the differences in carbon content between steel and pig iron, and the method of distinguishing steel from pig iron by grinding with a grinding wheel.

The article focuses on the question of "why pots are so brittle, spoons are so resilient, and knives are so sharp", explaining that although cooking pots, spoons, and kitchen knives are all made of iron, they are respectively made of cast iron, wrought iron, and steel. Due to differences in carbon content and production processes, there are significant differences in their properties such as brittleness and resilience among the three types of products.

This article introduces the reasons why French Emperor Napoleon III loved aluminum crowns and tableware. In the 19th century, aluminum smelting technology was complex, with low output and a value far exceeding that of gold and silver. At the same time, it describes how American youth Hall and French youth Héroult independently invented the electrolytic aluminum production process in the late 19th century, greatly reducing the production cost of aluminum and making aluminum accessible to ordinary people, instead of being a luxury reserved for the nobility.