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Element No. 30 of the periodic table

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synonym Zn (Zn) generally refers to zinc (element No. 30 in the periodic table of elements)

This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

Zinc is a chemical element , its chemical symbol is Zn, its Atomic number It is 30, and it is in the fourth cycle and the second B group in the periodic table of chemical elements. Zinc is a light gray transition metal It is also the fourth "common" metal. In modern industry, zinc is Battery Irreplaceable and important in manufacturing Metal 。 In addition, zinc is also one of the essential trace elements for human body, which plays an extremely important role.

Chinese name: zinc
Foreign name: zinc
molecular weight: sixty-five point three eight
CAS login number: 7440-66-6
Melting point: 419.53 ℃
Boiling point: 907 ℃
Density: 7.14 g/cm³
Application: Battery , automobile, electric power, electronics and construction, etc
State of matter: solid state
Heat of fusion: seven point three two kJ·mol −1
Heat of vaporization: 123.6kJ·mol −1
Specific heat capacity: 25.470J·mol −1 ·K −1
Electronegativity: 1.65 (Pauling scale)

Atomic radius: 134pm
Covalent radius: 122±4pm
Vander Waals radius: 139pm
crystal structure: Hexagonal close packed lattice
Magnetic sequence: Diamagnetism
resistivity: （20°C）59.0n Ω·m
Thermal conductivity: 116W·m −1 ·K −1
Coefficient of expansion: （25°C）30.2µm·m −1 ·K −1
Young's modulus: 108GPa
shear modulus: 43GPa
Electronic layer: K-L-M-N^[4]
Electron layer distribution: 2-8-18-2^[4]
Electronic layout: [Ar]3d ten 4s two^[4]

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Figure 1 Zinc

Zinc, its name“ zinc” Derived from the Latin Zincum, meaning "white thin layer" or "white sediment". The chemical symbol is Zn, its atomic number is 30, and its atomic weight is 65.38. Zinc is a silvery white slightly bluish metal with a density of 7.14g/cm three The melting point is 419.5 ℃. stay room temperature Lower, more brittle; It becomes soft at 100~150 ℃; After exceeding 200 ℃, it dries again. Zincate chemical property Lively, in normal atmospheric temperature Lower atmosphere A thin and dense layer of Basic zinc carbonate Membrane, can prevent further oxidation 。 When the temperature reaches 225 ℃, zinc is severely oxidized.

Zinc is difficult in the air burning , on oxygen It emits strong white light. There is a layer on the zinc surface zinc oxide , emerging when burning White smoke The main component of white smoke is zinc oxide, which not only blocks the combustion of zinc, but also refracts the flame color to form a pale light. Zinc is easily soluble in acid , also easy to follow solution in substitution Gold, silver, copper, etc. The melting point of zinc oxide film is high, but the melting point of metal zinc is very low, so the zinc sheet is heated on the alcohol lamp, and the zinc sheet melts and becomes soft, but does not fall, because of the role of the oxide film. Zinc is mainly used for steel 、 metallurgy 、 Mechanics 、 electrical 、 chemical industry 、 light industry , military, medicine and other fields.

Regulatory information : Zinc powder is also called zinc particle, high-purity zinc, arsenic free zinc, etc Explosive Items according to《 Regulations on Safety Management of Hazardous Chemicals 》Accepted Public Security Department control.

Interpretation of ancient books

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《 Alliteration 》Zu like cut, Yinzi. Gangya. The Jade Chapter is the same as Yu.

Physical and chemical properties

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Physical and chemical constants

Figure 5 Zinc Particles

Relative atomic weight

The relative atomic weight is 65.38 (generally 65 in junior high school)^[3]

Properties of zinc

Zinc is a blue white metal. When the temperature reaches 225 ℃, zinc oxidation is intense. Zinc is easily soluble in acid and can easily displace gold, silver, copper, etc. from the solution. Zinc in nature Medium, mostly sulfide Status exists. The main zinc bearing minerals are sphalerite 。 There are also a few oxidized ores, such as Smithsonite , such as smithsonite and Heteropolar ore 。

atomic structure

Atomic radius (calculated value): 135 (142) pm

Figure 6 Alkaline zinc manganese battery

Covalent radius: 131pm

Vander Waals radius: 139pm

Electronic layer: K-L-M-N

Extranuclear electron arrangement ：2，8，18，2

Electronic layout: [Ar] 3d ten 4s two^[4]

Number of nuclear charges: 30

Content (ppm)

Element content in the sun: 2

Element content in seawater: 0.00005（ trace element ）

Content in the crust: 75 (trace elements)

Figure 7 Zinc in ampoules

Oxidized state

Main oxidation state:+2

Others:+1

Ionization energy (unit: kj/mol)

M - M + nine hundred and six point four

M + - M 2+ one thousand seven hundred and thirty-three point three

M 2+ - M 3+ three thousand eight hundred and thirty-two point six

M 3+ - M 4+ five thousand seven hundred and thirty

M 4+ - M 5+ seven thousand nine hundred and seventy

M 5+ - M 6+ ten thousand and four hundred

M 6+ - M 7+ twelve thousand and nine hundred

M 7+ - M 8+ sixteen thousand and eight hundred

M 8+ - M 9+ nineteen thousand and six hundred

Color contrast of Al and Zn: Al is very white, Zn is bluish

M 9+ - M 10+ twenty-three thousand

Cell parameter

Crystal structure: close packed hexagonal

a = 266.49 pm

b = 266.49 pm

c = 494.68 pm

α = 90°

β = 90°

γ = 120° isotope

isotope	abundance	half life	decay mode	Decay energy MeV	Decay product
sixty-four Zn	48.6%		stable
sixty-five Zn	artificial	244.26 days	Electron capture	one point three five two	sixty-five Cu
sixty-six Zn	27.9%		stable
sixty-seven Zn	4.1%		stable
sixty-eight Zn	18.8%		stable
seventy-two Zn	artificial	46.5 hours	Beta decay	zero point four five eight	seventy-two Ga

Other properties

Common zinc containing alloy ： Tinplate ——Tin plated steel sheet; brass ——The alloy of zinc and copper has long been used by the ancients. The production of brass may be one of the earliest accidental discoveries in metallurgy.

Volume: 9.16 × 10 -6 m three /mol

Sound speed: 3700m/s (293.15K)

Electronegativity: 1.65 (Pauling scale)

Specific heat capacity: 390J/(kg · K)

Conductivity: 16.6 × 10 six /（m·Ω）

Thermal conductivity: 116W/(m · K)

Mohs hardness ：2.5

Vaporization heat: 115.3kJ/mol

Melting heat: 7.322kJ/mol

Vapor pressure: 192.2Pa (692.73K)

chemical property

The chemical properties of zinc are similar to that of aluminum, so the chemical properties (amphoteric) of zinc can usually be inferred from the properties of aluminum.

① Simple zinc, which can be mixed with acid React with alkali Reaction.

② Zinc oxide and Zinc hydroxide , soluble in both acid and alkali.

Elemental zinc

Zinc hydroxide

Zinc chloride

Zinc sulfide

Zinc nitrate

Zinc complex

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Discovery History

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Zinc was known to the Romans but rarely used. It was first recognized for its metal itself in India. There was a zinc furnace in Zawar, Rajasthan, with a large amount of zinc, which proved that large-scale refining took place between 1100 and 1500 years.

The large-scale refining of zinc was carried out in China in the 16th century. The ship of the East India Company sank on the coast of Sweden. In 1745, its cargo was Chinese zinc. The analysis of the recovered ingots proved that they were almost pure metals.

In 1668, P Moras de Respour， The metal zinc was extracted from zinc oxide, but Europe believed that zinc was discovered by German chemist Andreas Marggraf in 1746, and he was indeed the first to confirm that it was a new metal.

Historical records

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Zinc products

Zinc has also been known since ancient times chemical compound Of element one of. Alloy made by melting zinc ore and copper—— brass , used by ancient people. However, metallic zinc was obtained much later than copper, iron, tin and lead. It is generally believed that this is because when carbon and zinc ore are co heated, the temperature quickly reaches more than 1000 ℃, while the boiling point of metallic zinc is 906 ℃, so zinc becomes a vapor state and disappears with smoke, which is difficult for ancient people to detect. Only when people master the method of condensing gas, Simple substance Zinc can be obtained.

China was the first country to discover and use zinc in the world, and China was the first country to produce zinc on a large scale in the 10-11th century. Late Ming Dynasty Song Yingxing Authored《 Tiangong Kaiwu 》The book contains the world's earliest record of zinc smelting technology. From 1750 to 1850, people began to treat diseases with zinc oxide and zinc sulfide.

In 1869, Raulin found that zinc was present in and necessary for living organisms. In 1963, human body Zinc deficiency disease , so zinc began to be listed as Human essential nutrients 。 The production process of zinc is very simple calamine (namely, rhodochrosite ore) is filled in the pottery pot, sealed, stacked into a cone, and the gap between the pots is filled with charcoal. The extracted metal zinc ingots can be obtained by breaking the pots.

In addition, Wang Lian (1888-1966), a pioneer in the study of the history of chemistry and analytical chemistry in China, analyzed the ancient coins of the Tang, Sui, Ming and Qing dynasties in 1956 and found that the Shaosheng coins of the Song Dynasty contained high zinc content. The practical application of zinc may be better than《 Tiangong Kaiwu 》It is still early.

resource distribution

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There are few single zinc ores, and zinc ore resources are mainly Lead-zinc ore 。 China Copper zinc ore There are abundant resources, except Shanghai 、 Tianjin 、 Hong Kong In addition, there are lead-zinc minerals. There are more than 700 places of origin, with a total lead reserve of 35.72 million tons, ranking fourth in the world; The reserves of zinc are 93.84 million tons, ranking fourth in the world. From the perspective of provincial comparison, Yunnan Lead reserves account for 17% of the country's total reserves, ranking first in the country. Guangdong Inner Mongolia , Gansu, Jiangxi, Hunan and Sichuan, proved reserves All above 2 million tons. Yunnan is the largest zinc reserve in China, accounting for 21.8% of the country; Inner Mongolia takes the second place, accounting for 13.5%; Other provinces (regions) such as Gansu, Guangdong, Guangxi and Hunan are also rich in zinc ore resources, all of which are more than 6 million tons. Lead zinc ores are mainly distributed in western Yunnan Lanping Regions, Yunnan and Sichuan, Nanling, Qinling- Qilian Mountains Region and Inner Mongolia Wolf Mountain -Zhaertai area. from deposit In terms of types, there are granite types related to granite (Lianping, Guangdong) Skarn Type (Hunan Shuikou Mountain ）Porphyry type (Yunnan Yao An ）Deposit, with marine facies Volcanic related deposit (Xitieshan, Qinghai) continental facies The deposits in volcanic rocks (Lengshuikeng in Jiangxi Province and Wubu lead-zinc deposit in Zhejiang Province) occur in marine facies carbonate (Guangdong Fan Kou ）、 mudstone -Lead and zinc deposits in clastic rock series (Xicheng lead and zinc deposit in Gansu), lead and zinc deposits in marine or continental sandstone and conglomerate (Jinding, Yunnan), etc. The lead and zinc ore mineralization era is from Archean to Cenozoic, and the Paleozoic lead and zinc ore resources are rich.

Market conditions

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After the financial crisis, various countries have launched rescue plans, and major central banks have also released liquidity. The United States has continued to expand the volume, and China has launched four trillion yuan to promote economic recovery. The abundant liquidity has made the financial attribute occupy the main position, pushing up the zinc price in 2010. According to the Forecast Report on the Competition Situation and Investment Development of China's Zinc Industry 2013-2017, the global economy is stabilizing, the United States is slowly recovering, and the market's expectation of QE3 withdrawal is gradually increasing. If the U.S. economic policy changes, the U.S. dollar will strengthen, and zinc prices will be greatly affected by it. At the same time, it is worth noting that the economic recovery has also brought demand recovery to a certain extent, and the game of the two attributes will jointly determine the future trend of zinc price.

American financial crisis Later, the continuous loose monetary policy promoted economic and employment growth. Although the marginal utility of monetary easing policy decreased, it can be seen that the slow growth of US GDP growth and the slow improvement of the employment market indicate that the US economy is recovering weakly. The recovery of the U.S. economy and the recovery of the real estate market led to an increase in demand for zinc, but this weak recovery situation is still relatively weak, and the demand for zinc is also limited.

quality index

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Grade	Zn（%）	Cu（%）	Pb（%）	Fe（%）
one	≥55	≤0.8	≤1.0	≤6.0
two	≥53	≤0.8	≤1.0	≤6.0
three	≥50	≤1.0	≤1.5	≤8.0
four	≥48	≤1.0	≤1.5	≤12.0
five	≥45	≤1.5	≤2.0	≤12.0
six	≥43	≤1.5	≤2.0	≤12.0
seven	≥2.0	≤2.5	≤14.0
eight	≥40	≤2.0	≤2.8	≤18.0

Product use

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About half of the total consumption of zinc in the world is used for Galvanized About 10% for brass and bronze, less than 10% for Zinc base alloy About 7.5% for Chemicals And about 13% are used to manufacture dry cells, which are in the form of zinc cakes and zinc plates. The International Lead and Zinc Research Group predicts that the global zinc consumption in 2004 will increase by 4.8% compared with 9.85 million tons in 2003, and will increase by 4.3% in 2005. It is estimated that China will account for a quarter of the world's total zinc consumption in 2005, and its consumption growth is partly due to the increase in the consumption of galvanized steel. In contrast, the United States may account for only one tenth of global zinc demand.

(1) Zinc plating has excellent atmospheric corrosion resistance, and it is easy to form a protective film on the surface at room temperature. Therefore, zinc is most widely used in the zinc plating industry. It is mainly used for surface coating of steel and steel structural parts (such as galvanized sheet), and is widely used in automobile, construction, shipbuilding, light industry and other industries. After the 21st century, western countries began to try to directly use zinc alloy sheets as roof covering materials. Their service life can be as long as 120-140 years, and they can be recycled. The service life of galvanized iron sheets as roof materials is generally 5-10 years. After the 21st century, the amount of hot-dip galvanizing of steel strip has increased significantly. electroplate Zinc is also used, but this method is generally used for thinner coatings and different Surface finish 。 The use of coatings containing zinc powder is another method of coating; Objects in continuous contact with water, such as large steel members used for ships, bridges and offshore oil and gas derrick, can be protected only by connecting with large zinc blocks, but the zinc blocks need to be replaced regularly.

（2） kirsite Used in automobile manufacturing and machinery industry. Zinc has suitable mechanical properties. The strength and hardness of zinc itself are not high, but the strength and hardness are greatly improved after the addition of aluminum, copper and other alloy elements, especially the appearance of zinc copper titanium alloy, whose comprehensive mechanical properties have approached or reached aluminium alloy The creep resistance of brass and gray cast iron has also been greatly improved. Therefore, zinc copper titanium alloy has been widely used in hardware production. It is mainly die casting, used for the production of parts and components of automobiles, buildings, some electrical equipment, household appliances, toys, etc. Many zinc alloys have excellent processability, Pass processing rate Up to 60% - 80%. The medium pressure performance is superior, it can be used for deep drawing, and has self-lubricating property, which extends the service life of the mold. It can be used for brazing, resistance welding or electric arc welding ( helium Middle) welding, and the surface can be plated and painted, Machinability Good. It has advantages under certain conditions. It is generally used in the machinery manufacturing industry. Zinc plate containing a small amount of lead, cadmium and other elements can be made Zinc manganese dry battery negative pole , printed zinc plate, powder corrosion photographic plate and offset printing plate, etc.

(3) Zinc can be used to make batteries. For example: Zinc manganese battery as well as Zinc air battery 。

Zinc manganese battery: As the negative active material, zinc is also used as the container and negative lead of the battery, and is the main material that determines the storage performance of the battery. There is a small amount of cadmium and lead in the zinc sheet. Cadmium can enhance the strength of zinc, and lead can improve the ductility of zinc. Both cadmium and lead can increase the overpotential of hydrogen on zinc electrode, reduce the self discharge of zinc electrode, and slow down the corrosion of zinc sheet and the release of hydrogen. If the zinc sheet contains Cu, Fe, Ni, etc., H will be reduced two Precipitated on zinc electrode Overpotential Accelerate the self discharge of the battery during storage, so these harmful impurities must be strictly controlled.

Zinc air battery: Zinc air battery Also called zinc oxygen battery, it is a kind of metal air battery. The theoretical value of specific energy of zinc air battery is 1350W · h/kg, and the specific energy of the latest battery has reached 230Wh/kg, almost 8 times that of lead-acid battery. It can be seen that the development space of zinc air battery is very large. The zinc air battery is generally "mechanically charged" by replacing the zinc electrode. The electrode replacement can be completed in a few minutes. With the new zinc electrode, the "charging" time is very short and very convenient. The development of such batteries saves the construction of social security facilities such as charging stations. Zinc electrodes can be purchased in supermarkets, battery stores, auto parts stores, etc., which is very beneficial to the popularization of this battery electric vehicle. The battery has the advantages of small size, large charge capacity, small mass, normal operation in a wide temperature range, corrosion free, safe and reliable operation. However, the zinc electrode consumes more energy in the process of electrolytic reduction. It consumes 2500 kilowatt hours of electricity per ton of zinc oxide to reduce to zinc, so it is expensive to use it in electric vehicles. The charge capacity of the test battery is only 5 times that of the lead-acid battery, which is not ideal. However, the charge of five times that of lead-acid batteries has attracted the attention of the world. The United States, Mexico, Singapore and some European countries have tried it out on postal buses, buses and motorcycles, which is also a promising battery for electric vehicles.

In addition, zinc has good electromagnetic resistance. The conductivity of zinc is 29% of that of standard electrical copper, Zinc plate It is a very effective shielding material. At the same time, because zinc is non-magnetic, it is suitable to be used as the material of instrument parts, instrument shells and coins. At the same time, zinc itself and other metals will not produce sparks, so it is suitable for underground explosion-proof equipment. Widely used in rubber, paint, enamel, medicine, printing, fiber and other industries. Zinc has appropriate chemical properties. Zinc can be mixed with NH four CI acts, releasing H + Positive ion. Zinc- manganese dioxide The battery makes use of this feature of zinc. The shell of the battery is made of zinc alloy, which is the battery electrolyte In addition, it participates in the battery reaction to form the anode of the battery. Its performance is also widely used in the pharmaceutical industry. Zinc can react with acid or strong base to release hydrogen. Zinc fertilizer （ zinc sulfate 、 Zinc chloride ）Promotive plant cell Respiration, carbohydrate metabolism, etc. zinc powder 、 Lithopone 、 Zinc chrome yellow It can be used as pigment. Zinc oxide can also be used in medicine, rubber, paint and other industries.

Domestic production base

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The production layout of China's lead and zinc industry is based on the lead and zinc mineral products After more than 40 years of development and construction, five production bases supporting lead and zinc mining, beneficiation, metallurgy and processing have been formed in Northeast China, Hunan, Guangdong, Guangxi, Yunnan, Sichuan and Northwest China. Their lead output accounts for more than 85% of the total national output and zinc output accounts for 95% of the total national output.

one Northeast Lead and Zinc Production Base 。 Northeast China is one of the earliest lead and zinc production bases in China. As early as the early 1950s, its lead production accounted for more than 80% of the national lead production, and played an important role in China's lead and zinc production. The Northeast Base is mainly composed of seven mines and two factories, namely Qingchengzi Lead Zinc Mine, Bajiazi Lead Zinc Mine, Chaihe Lead Zinc Mine (now closed), Huanren Copper Zinc Mine, Hongtoushan Copper Zinc Mine, Xilin Lead Zinc Mine, Tianbaoshan Lead Zinc Mine, Shenyang Smelter and Huludao Zinc Plant. Seven mines and two factories are not only the pillar factories and mines of the northeast lead and zinc production base, but also the base for cultivating scientific and technological talents. In the 1960s and 1970s, he sent a large number of experienced scientific and technological personnel, management personnel and production technicians to newly built lead-zinc enterprises across the country, making positive contributions to the development of China's lead-zinc industry.

2. Hunan lead and zinc production base. Hunan is rich in lead and zinc mineral resources, most of which can be developed and utilized. The lead-zinc plant and mine in the base were built in the 1950s and 1960s Shuikoushan Mining Bureau Hunan lead and zinc production base composed of Taolin Lead and Zinc Mine, Huangshaping Lead and Zinc Mine, Dongpo Lead and Zinc Mine and Zhuzhou Smelter is the largest lead and zinc production base of domestic raw materials in China and plays an important role in national output.

3. Lead and zinc production base in Guangdong and Guangxi. Guangdong and Guangxi are rich in lead and zinc resources. The two provinces are one of the large-scale lead and zinc production bases in China formed in the 1970s. Guangdong Fankou Lead Zinc Mine And Shaoguan Smelter, followed by Bingcun Lead Zinc Mine, Changhua Lead Zinc Mine and Dajianshan Lead Zinc Mine. Guangxi has Siding Lead Zinc Mine, Daxin Lead Zinc Mine, Hesan Lead Zinc Mine, Liuzhou Zinc Products Factory and Dachang Mining Bureau.

4. Yunnan Sichuan lead and zinc production base. Yunnan is very rich in lead and zinc mineral resources, with lead and zinc reserves ranking first in the country. The base's lead and zinc enterprises were also built in the 1950s and 1960s, mainly including Huize Lead and Zinc Mine, Lancang Laochang Lead and Zinc Mine, Kunming Smelter and Gejiujijie Smelter. Yunnan's lead and zinc mineral resources have broad prospects for development. In the 1990s, Jinding Mine of super large lead and zinc deposits was built. Sichuan has two major mines, Huidong Lead Zinc Mine and Huili Lead Zinc Mine, as well as a number of small and medium-sized mines. Since the 21st century, the output of lead zinc concentrates has increased sharply.

5. Northwest lead and zinc production base. Northwest China is also rich in lead and zinc mineral resources, which are mainly distributed in Gansu, Shaanxi and Qinghai provinces. Moreover, the explored reserves of the western metallogenic belt have increased significantly, and the resource prospect is very considerable. Lead and zinc production in the base Baiyin Nonferrous Metals Mainly, there are Baiyinchang Xiaotieshan Lead Zinc Mine, the Third Smelter and Northwest Lead Zinc Smelter, Shaanxi has Qiandongshan Lead Zinc Mine, Erlihe Lead Zinc Mine, Yindongliang Lead Zinc Mine and Qinghai Xitieshan Mining Bureau. The production of lead and zinc in northwest China is less, but the development prospect is considerable. First, there are rich lead-zinc mineral resources. Located in the Xicheng Fengtai ore belt at the junction of Gansu and Shaanxi, more than 10 large and medium-sized lead-zinc silver gold deposits have been explored over the past 20 years, of which Changba Lijiagou lead-zinc deposits have reached a super large scale and silver deposits have reached a large scale. Second, Changba is working hard to build a large mine, which will become the main mineral raw material supply base for the northwest smelter and one of the large lead and zinc mines in China.

In addition to the above five major lead and zinc production bases, a number of small and medium-sized mines have also been built in Inner Mongolia, Jiangxi, Guizhou and other provinces and regions. Among them, Wutonghua Lead Zinc Mine, Baiyinnuo Lead Zinc Mine, Ongniud Banner Dongzi Lead Zinc Mine and other mines in Inner Mongolia. Inner Mongolia is one of the main provinces and regions producing lead and zinc concentrates in China, with a great development prospect. Jiangxi has Yinshan Lead Zinc Mine, etc. Guizhou has Hezhang Lead Zinc Mine, Shanshulin Lead Zinc Mine, etc.

Product hazard

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Invasion route: inhalation and ingestion.

Inhalation may cause thirst, dry cough, headache, dizziness, high fever, chills, etc. Dust is irritating to eyes. Oral irritation of stomach intestine 。 Long term repeated contact is irritating to the skin.

Safety measures

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1. Store in a cool and dry place, away from fire and heat source.

2. and Oxidant , amine, sulfur, phosphorus, acid and alkali.

3. Fire extinguishing: dry powder, dry sand. Disable water and foam 。

Zinc and Health

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Physiological function of zinc

Maintain normal appetite

Zinc deficiency will lead to decreased taste, anorexia, partial food and even anorexia.

Enhance human immunity

Zinc is the nutrient for thymus development of immune organs. Only sufficient zinc can effectively ensure thymus development and normal differentiation T lymphocytes Promote cellular immune function.

Zinc can help growth and development, intellectual development and improve immunity. Lack of zinc will have a serious impact on our body, especially on growth and development. Therefore, sufficient zinc is necessary for growth and intellectual development. In addition to balanced diet, don't forget to properly supplement nutrition.

Symptoms of zinc deficiency

children

Taste disorder: anorexia, partial food or anorexia;

Skin disease: easy to suffer mouth ulcer , the damaged wound is not easy to heal, adolescent acne, etc;

Poor growth and development: short and thin;

Immune function declines, often catches cold and has fever;

pregnant woman

Pregnancy reaction aggravation: acidophilia, vomiting aggravation

Intrauterine Fetal growth retardation : Causes premature infants, low birth weight infants

Increased complications of delivery: prolonged labor and abortion

Recommended intake

Age (years)	RNI（mg）	UL（mg）
0~	one point five
0.5~	eight	thirteen
1~	nine	twenty-three
4~	twelve	twenty-three
7~	thirteen point five	twenty-eight
	men and women	men and women
11~	18.0 15.0	37 34
14~	19.0 15.5	42 35
18~	15.0 11.5	45 37
fifty	11.5 11.5	37 37
pregnant woman		thirty-five
early stage	eleven point five
metaphase	sixteen point five
advanced	sixteen point five
wet nurse	twenty-one point five	thirty-five

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