Mercury, lead, arsenic, and cadmium are highly toxic elements. They have different uses in many fields, but they also pose potential hazards and cannot be ignored.
Mercury, a liquid metal, has unique physical and chemical properties. In ancient times, it was often used in alchemy, and alchemists wanted to use it to refine longevity pills. Although it was ineffective, it preserved experience for later chemical research. In the field of medicine, mercury compounds were used as disinfectants and preservatives in the past, but due to toxicity, they are now rarely used. In industry, mercury is used to make thermometers and sphygmomanometers, because its thermal expansion and contraction properties accurately reflect temperature and pressure changes. However, mercury evaporates to form mercury vapor, which can damage the nervous system and kidneys when inhaled into the human body, causing tremors, insomnia, memory loss and other symptoms.
Lead is soft and resistant to corrosion. In ancient times, it was often cast as currency and utensils because it was easy to process and form. In the field of construction, it was used to make water pipes, but lead would dissolve in water and endanger human health. In modern times, lead is widely used to make lead-acid batteries, which supply energy for cars, electric vehicles, etc. However, when lead enters the human body, it will affect the development of the nervous system, especially in children. It can cause mental decline and abnormal behavior. It can also affect the hematopoietic system and cardiovascular system.
Arsenic, a variety of compounds. Ancient arsenic (arsenic trioxide) was often used as a poison. However, a small amount of arsenic compounds were used as drugs in the field of medicine, such as the treatment of certain blood In agriculture, arsenic-containing pesticides have been used to prevent insects, but their residues can pollute soil and water sources. Arsenic enters the human body and can damage the skin, liver, kidneys and other organs. Long-term exposure can cause skin cancer, lung cancer, etc.
Cadmium has good corrosion resistance and electroplating properties. It is often plated on metal surfaces to prevent corrosion in industry and is also used in the manufacture of nickel-cadmium batteries. Cadmium enters the human body and can accumulate in the kidneys and bones, causing renal insufficiency and osteoporosis. "Pain disease" is a typical disease caused by cadmium pollution. Patients have severe bone pain and are prone to fractures.
Although mercury, lead, arsenic, and cadmium have certain uses in human development, due to toxicity, caution must be taken when using them, and protection and pollution prevention and control must be done to ensure human health and ecological environment safety.

Mercury, bromine, gallium, and cesium all have wonderful physical properties.
Mercury is a liquid metal at room temperature, and silver optical flows like a spiritual liquid. Its melting point is as low as -38.87 ° C, and its boiling point is 356.6 ° C. The density of mercury is quite large, about 13.59 grams/cubic centimeter, which is heavier than normal matter. Its fluidity is very good, like silver beads rolling, which is elusive. And mercury has a certain evaporation, which can be slowly volatilized in the air, and its vapor is toxic. Be careful.
Bromine is the only non-metallic element that is liquid at room temperature and pressure. It is red-brown in color and has a strong pungent smell, which is unbearable. Bromine has a melting point of -7.2 ° C and a boiling point of 58.76 ° C. Its density is 3.119 grams per cubic centimeter, which is heavier than water. Bromine is volatile, and its reddish-brown mist can be seen rising in the air, and bromine is highly corrosive, touching the skin.
Gallium, seemingly ordinary, but its melting point is extremely low, only 29.78 ° C, slightly higher than normal temperature, placed in the palm of your hand, melts when heated, and turns into a liquid, like magic. Its boiling point is extremely high, reaching 2403 ° C. The density of gallium is about 5.904 grams per cubic centimeter. Solid gallium is soft, can be easily cut, and has good electrical conductivity.
Cesium, silver-white in color, soft as wax, deforms when touched. Its melting point is extremely low, 28.44 ° C, and it melts into a liquid when it is slightly hot. The chemical properties of cesium are extremely active, and it reacts violently when exposed to water. It explodes and ignites, releasing hydrogen. Its density is 1.879 g/cm3. Among alkali metals, cesium has the strongest metallic properties and is extremely sensitive to light. It is often used in optoelectronic devices.
These four things are either hidden in deep mountain veins or hidden in the field of chemistry. With their unique physical properties, they are all used in scientific research and industry. They are treasures that nature has bestowed on our generation. We should make good use of them.

1. Mercury is active, liquid at room temperature, and has a metallic luster. Although it appears to be relatively stable under common conditions, its chemical properties are quite unique. Mercury can form amalgam with a variety of metals, which is relatively easy to occur, indicating that mercury is more active in metal interactions. And mercury is easy to react with oxygen. When heated, it can quickly combine with oxygen to form mercury oxide.
2. Bromine is the only non-metallic element that is liquid at room temperature and pressure, and its chemical properties are active. Bromine has strong oxidizing properties and can react with many metals and non-metals. For example, it can react violently with sodium metal to form sodium bromide. In the field of organic chemistry, bromine is often used as an important reagent, participating in various reactions such as substitution and addition, which shows that its chemical properties are active and not stable.
3. Astatine is a halogen element and is radioactive. Due to its short half-life and minimal content in nature, the study of its chemical properties is limited. However, based on the law of gradual changes in the properties of halogen elements, astatine should have a certain degree of oxidation and can react with metals to form corresponding compounds. It is inferred from theory and limited experiments that astatine is not a chemically stable substance.
In summary, mercury, bromine, and astatine are all non-chemically stable substances, and each exhibits relatively active chemical properties under different conditions.

To prepare 1-ether, 3-alkyne, and 5-bromobenzene, the following methods can be used.
The method of making ethers is commonly used in the Williamson synthesis method. The reaction of halogenated hydrocarbons with sodium alcohols, such as the reaction of halogenated alkanes with sodium alcohols in an appropriate solvent, the halogen atoms are replaced by alkoxy groups to form ethers. For example, bromoethane is co-heated with sodium ethanol to form ethyl ether. The reaction mechanism is that the alkoxy negative ion of sodium alcohols acts as a nucleophilic reagent to attack the α-carbon atom of halogenated hydrocarbons, and the halogen ions leave. This is a nucleophilic substitution reaction. There is also an intermolecular dehydration method of alcohols. Under the action of dehydrating agents such as sulfuric acid, two-molecule alcohols can remove a molecule of water to form ethers. However, this method is more suitable for primary alcohols, and secondary alcohols and tertiary alcohols are prone to side reactions, such as elimination of the reaction to form olefins.
As for the synthesis of ethylene, the nucleophilic substitution reaction of acetylene is commonly used. Acetylene reacts with sodium metal to obtain sodium acetylene, which reacts with halogenated hydrocarbons and can introduce alkyl groups to obtain corresponding alkynes. To synthesize 3-alkynes, sodium acetylene can be obtained first, and then reacted with suitable halogenated hydrocarbons. For example, reacted with 1-bromopropane, 1-pentyne In this reaction, the carbon anion of sodium acetylene has strong nucleophilicity, attacking the α-carbon atom of the halogenated hydrocarbon, and the halogen ion leaves to realize the growth of the carbon chain and generate alkynes. In addition, the dehalogenation method of o-dihalogenated alkanes can also be used. Under the action of strong bases such as potassium hydroxide alcohol solution, the elimination reaction of o-dihalogenated alkanes occurs to form alkynes.
Synthesis of 5-bromobenzene can be achieved through the bromination reaction of benzene. Using benzene as a raw material, under the action of catalysts such as iron bromide, benzene and bromine undergo an electrophilic substitution reaction, and bromine atoms replace hydrogen atoms on the benzene ring to obtain bromobenzene. To introduce If there are some groups on the benzene ring, it can affect the position of the subsequent substitution reaction. If there is a power supply group connected to the benzene ring, it is an ortho-and para-position group, which can make the subsequent substituents mainly enter the ortho-and para-position; if there is an electron-absorbing group, it is an meso-position group, so that the subsequent substituents mainly enter the meso-position. To obtain 5-bromobenzene, a suitable positioning group can be introduced into the benzene ring to guide the bromine atom into the desired position, and then the positioning group can be removed by an appropriate reaction.

Oil, pulp, lacquer, wax, etc., should be paid attention to in the way of storage and transportation.
First, the storage place must be dry, cool and well ventilated. Oil is flammable, and if it is placed in a high temperature or unventilated place, it is prone to fire risk. The same is true for pulp. In a high temperature and humid place, it may deteriorate and rot, and lose its original properties. Paint contains many chemicals, which can change in adverse environments or cause changes in composition, affecting its effectiveness. Wax is easy to melt when heated, so it should be placed in a cool place to maintain its shape and quality.
Second, the method of packaging is crucial. Oil should be stored in a tightly sealed container to prevent it from evaporating, and to avoid contact with air and moisture, causing it to oxidize and deteriorate. The packaging of pulp should be able to resist external shocks and collisions to prevent it from leaking. The container of paint should be corrosion-resistant, because the ingredients in the paint or chemical reaction with ordinary materials. The packaging of wax should be able to maintain its shape stable and prevent extrusion deformation.
Third, when transporting, the bumps of the road cannot be ignored. Oil, pulp, paint and wax should be properly fixed to prevent them from being damaged due to shaking and collision during transportation. And the temperature and humidity in the means of transportation should also be adjusted appropriately. If the oil is transported at high temperature, it is not only easy to evaporate and lose, but also increases the risk of safety; if the wax is heated, it may melt and adhere, which will affect its quality and use.
Fourth, when handling, the action should be gentle. Oil drums, pulp drums, paint drums, wax blocks, etc., should not be thrown or collided to prevent the container from breaking and material leakage. And the person handling, when he knows the characteristics of various materials and follows the corresponding operating specifications, can keep the storage and transportation safe and smooth, so that the oil, pulp, paint and wax do not lose their use.