110-791: The Second Historical Archives of China ( SHAC ; 中国第二历史档案馆 ) is a central-level national archive located in Nanjing, Jiangsu , under the National Archives Administration of China . Established in February 1951, it is responsible for collecting and managing archives of central government agencies during the Republic of China period , from 1912 to 1949. As of 2024, the archive held more than 2.58 million volumes, with shelves more than 50 thousand meters long cumulatively. The archive cover major historical events and figures in various historical stages of
220-440: A chemical equation . While in a non-nuclear chemical reaction the number and kind of atoms on both sides of the equation are equal, for a nuclear reaction this holds true only for the nuclear particles viz. protons and neutrons. The sequence of steps in which the reorganization of chemical bonds may be taking place in the course of a chemical reaction is called its mechanism . A chemical reaction can be envisioned to take place in
330-756: A 1671 account by a French missionary. The commoners and officials in Beijing and Nanjing were waiting to support whichever side won. An official from Qing Beijing sent letters to family and another official in Nanjing, telling them all communication and news from Nanjing to Beijing had been cut off, that the Qing were considering abandoning Beijing and moving their capital far away to a remote location for safety since Koxinga's iron troops were rumored to be invincible. Koxinga's forces intercepted these letters and after reading them Koxinga may have started to regret his deliberate delays allowing
440-861: A Japanese-collaborationist government known as the " Nanjing Regime " or "Reorganized National Government of China" led by Wang Jingwei was established in Nanjing as a rival to Chiang Kai-shek 's government in Chongqing. In 1946, after the Surrender of Japan , the KMT relocated its central government back to Nanjing. In April 1949, Communist forces crossed the Yangtze River and the Communist People's Liberation Army (PLA) captured Nanjing. The KMT government retreated to Canton ( Guangzhou ) until October 15, Chongqing until November 25, and then Chengdu before retreating to
550-467: A chemical reaction is said to have occurred. A chemical reaction is therefore a concept related to the "reaction" of a substance when it comes in close contact with another, whether as a mixture or a solution ; exposure to some form of energy, or both. It results in some energy exchange between the constituents of the reaction as well as with the system environment, which may be designed vessels—often laboratory glassware . Chemical reactions can result in
660-470: A chemical transformation is the rearrangement of electrons in the chemical bonds between atoms. It can be symbolically depicted through a chemical equation , which usually involves atoms as subjects. The number of atoms on the left and the right in the equation for a chemical transformation is equal. (When the number of atoms on either side is unequal, the transformation is referred to as a nuclear reaction or radioactive decay .) The type of chemical reactions
770-643: A decisive, single grand showdown as his father successfully did against the Dutch at the Battle of Liaoluo Bay , throwing away the surprise and initiative which led to its failure. Koxinga's attack on Qing held Nanjing which would interrupt the supply route of the Grand Canal leading to possible starvation in Beijing caused such fear that the Manchus (Tartares) considered returning to Manchuria (Tartary) and abandoning China according to
880-402: A definite composition and set of properties . A collection of substances is called a mixture. Examples of mixtures are air and alloys . The mole is a unit of measurement that denotes an amount of substance (also called chemical amount). One mole is defined to contain exactly 6.022 140 76 × 10 particles (atoms, molecules, ions, or electrons), where the number of particles per mole
990-412: A dense core called the atomic nucleus surrounded by a space occupied by an electron cloud . The nucleus is made up of positively charged protons and uncharged neutrons (together called nucleons ), while the electron cloud consists of negatively charged electrons which orbit the nucleus. In a neutral atom, the negatively charged electrons balance out the positive charge of the protons. The nucleus
1100-541: A directed beam in a vacuum in a mass spectrometer . Charged polyatomic collections residing in solids (for example, common sulfate or nitrate ions) are generally not considered "molecules" in chemistry. Some molecules contain one or more unpaired electrons, creating radicals . Most radicals are comparatively reactive, but some, such as nitric oxide (NO) can be stable. The "inert" or noble gas elements ( helium , neon , argon , krypton , xenon and radon ) are composed of lone atoms as their smallest discrete unit, but
1210-797: A fundamental level. For example, chemistry explains aspects of plant growth ( botany ), the formation of igneous rocks ( geology ), how atmospheric ozone is formed and how environmental pollutants are degraded ( ecology ), the properties of the soil on the Moon ( cosmochemistry ), how medications work ( pharmacology ), and how to collect DNA evidence at a crime scene ( forensics ). Chemistry has existed under various names since ancient times. It has evolved, and now chemistry encompasses various areas of specialisation, or subdisciplines, that continue to increase in number and interrelate to create further interdisciplinary fields of study. The applications of various fields of chemistry are used frequently for economic purposes in
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#17330849163351320-568: A history 2595 years long. In 541, Wu built Laizhu Town in Gaochun—because of its strong city, it was also called Gucheng. Fuchai , King of the State of Wu , founded a fort named Yecheng in today's Nanjing area in 495 BC. Wu was conquered by the State of Yue in 473 BC, and the city was rebuilt at the mouth of the Qinhuai River in the following year. Later it was called Yuecheng ( 越城 ) on
1430-434: A large section of the city for the bannermen 's cantonment, and occupied the former imperial Ming Palace , but otherwise the city was spared the mass murders and destruction that befell Yangzhou . Despite capturing many counties in his initial attack due to surprise and having the initiative, Koxinga announced the final battle in Nanjing in 1659 ahead of time giving plenty of time for the Qing to prepare because he wanted
1540-461: A long history, is among the world's top 20 universities ranked by the Nature Index . The ratio of college students to the total population ranks No.1 among large cities nationwide. Nanjing has the fifth-largest scientific research output of any city in the world. As of 2024, it has been ranked as the world's second most prolific scientific research center in earth and environmental sciences and
1650-573: A number of other names, and some historical names are now used as names of districts of the city. The city was known as Yuecheng and Jinling or "Ginling" ( 金陵 ) from the Warring States Era. Jianye ( 建业 ; Chien-yeh ), which means 'build an empire', was officially designated for the city during the Eastern Wu dynasty . The city first became a Chinese national capital as early as the Jin dynasty and
1760-411: A number of steps, each of which may have a different speed. Many reaction intermediates with variable stability can thus be envisaged during the course of a reaction. Reaction mechanisms are proposed to explain the kinetics and the relative product mix of a reaction. Many physical chemists specialize in exploring and proposing the mechanisms of various chemical reactions. Several empirical rules, like
1870-514: A population of 9,423,400. Situated in the Yangtze River Delta region, Nanjing has a prominent place in Chinese history and culture , having served as the capital of various Chinese dynasties , kingdoms and republican governments dating from the 3rd century to 1949, and has thus long been a major center of culture, education, research, politics, economy, transport networks and tourism, being
1980-405: A pure chemical substance that has its unique set of chemical properties, that is, its potential to undergo a certain set of chemical reactions with other substances. However, this definition only works well for substances that are composed of molecules, which is not true of many substances (see below). Molecules are typically a set of atoms bound together by covalent bonds , such that the structure
2090-609: A substance may undergo and the energy changes that may accompany it are constrained by certain basic rules, known as chemical laws . Energy and entropy considerations are invariably important in almost all chemical studies. Chemical substances are classified in terms of their structure , phase, as well as their chemical compositions . They can be analyzed using the tools of chemical analysis , e.g. spectroscopy and chromatography . Scientists engaged in chemical research are known as chemists . Most chemists specialize in one or more sub-disciplines. Several concepts are essential for
2200-453: Is a collective term for six Chinese dynasties mentioned above which all maintained national capitals at Jiankang. The six dynasties were: Eastern Wu (222–280), Eastern Jin dynasty (317–420) and four southern dynasties (420–589). At the end of the Eastern Han dynasty , the warlord Sun Quan , who ruled Jiangdong , moved his ruling office to Moling in 211 AD. The following year, he built
2310-414: Is a pure substance which is composed of a single type of atom, characterized by its particular number of protons in the nuclei of its atoms, known as the atomic number and represented by the symbol Z . The mass number is the sum of the number of protons and neutrons in a nucleus. Although all the nuclei of all atoms belonging to one element will have the same atomic number, they may not necessarily have
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#17330849163352420-409: Is a set of states of a chemical system that have similar bulk structural properties, over a range of conditions, such as pressure or temperature . Physical properties, such as density and refractive index tend to fall within values characteristic of the phase. The phase of matter is defined by the phase transition , which is when energy put into or taken out of the system goes into rearranging
2530-582: Is a very useful means for predicting the feasibility of a reaction and determining the state of equilibrium of a chemical reaction, in chemical thermodynamics . A reaction is feasible only if the total change in the Gibbs free energy is negative, Δ G ≤ 0 {\displaystyle \Delta G\leq 0\,} ; if it is equal to zero the chemical reaction is said to be at equilibrium . There exist only limited possible states of energy for electrons, atoms and molecules. These are determined by
2640-615: Is also considered a Beta (global second-tier) city classification, together with Chongqing , Hangzhou and Tianjin by the Globalization and World Cities Research Network , and ranked as one of the world's top 100 cities in the Global Financial Centres Index . As of 2021, Nanjing has 68 institutions of higher learning, including 13 double-first-class universities , ten 111-plan universities, eight 211 universities , and 97 academies. Nanjing University , which has
2750-422: Is also possible to define analogs in two-dimensional systems, which has received attention for its relevance to systems in biology . Atoms sticking together in molecules or crystals are said to be bonded with one another. A chemical bond may be visualized as the multipole balance between the positive charges in the nuclei and the negative charges oscillating about them. More than simple attraction and repulsion,
2860-439: Is also used to identify the composition of remote objects – like stars and distant galaxies – by analyzing their radiation spectra. The term chemical energy is often used to indicate the potential of a chemical substance to undergo a transformation through a chemical reaction or to transform other chemical substances. When a chemical substance is transformed as a result of its interaction with another substance or with energy,
2970-526: Is composed of gaseous matter that has been completely ionized, usually through high temperature. A substance can often be classified as an acid or a base . There are several different theories which explain acid–base behavior. The simplest is Arrhenius theory , which states that an acid is a substance that produces hydronium ions when it is dissolved in water, and a base is one that produces hydroxide ions when dissolved in water. According to Brønsted–Lowry acid–base theory , acids are substances that donate
3080-472: Is dense; the mass of a nucleon is approximately 1,836 times that of an electron, yet the radius of an atom is about 10,000 times that of its nucleus. The atom is also the smallest entity that can be envisaged to retain the chemical properties of the element, such as electronegativity , ionization potential , preferred oxidation state (s), coordination number , and preferred types of bonds to form (e.g., metallic , ionic , covalent ). A chemical element
3190-464: Is electrically neutral and all valence electrons are paired with other electrons either in bonds or in lone pairs . Thus, molecules exist as electrically neutral units, unlike ions. When this rule is broken, giving the "molecule" a charge, the result is sometimes named a molecular ion or a polyatomic ion. However, the discrete and separate nature of the molecular concept usually requires that molecular ions be present only in well-separated form, such as
3300-551: Is known as the Avogadro constant . Molar concentration is the amount of a particular substance per volume of solution , and is commonly reported in mol/ dm . In addition to the specific chemical properties that distinguish different chemical classifications, chemicals can exist in several phases. For the most part, the chemical classifications are independent of these bulk phase classifications; however, some more exotic phases are incompatible with certain chemical properties. A phase
3410-539: Is more easily transferred between substances relative to light or other forms of electronic energy. For example, ultraviolet electromagnetic radiation is not transferred with as much efficacy from one substance to another as thermal or electrical energy. The existence of characteristic energy levels for different chemical substances is useful for their identification by the analysis of spectral lines . Different kinds of spectra are often used in chemical spectroscopy , e.g. IR , microwave , NMR , ESR , etc. Spectroscopy
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3520-734: Is now Qixia . In the Jiangning district, ruins of primitive villages from the Neolithic Age were discovered. About 4000 years ago, dense Bronze Age primitive settlements appeared in the Qinhuai River Basin, labeled as the Hushu culture. The earliest cities in Nanjing were formed around these settlements. Due to the volume of archeological finds in the area related to the Taowu and Hushu cultures, many historians, anthropologists, and archeologists frequent
3630-468: Is the crystal structure , or arrangement, of the atoms. Another phase commonly encountered in the study of chemistry is the aqueous phase, which is the state of substances dissolved in aqueous solution (that is, in water). Less familiar phases include plasmas , Bose–Einstein condensates and fermionic condensates and the paramagnetic and ferromagnetic phases of magnetic materials. While most familiar phases deal with three-dimensional systems, it
3740-458: Is the quantum mechanical model . Traditional chemistry starts with the study of elementary particles , atoms , molecules , substances , metals , crystals and other aggregates of matter . Matter can be studied in solid, liquid, gas and plasma states , in isolation or in combination. The interactions, reactions and transformations that are studied in chemistry are usually the result of interactions between atoms, leading to rearrangements of
3850-502: Is the probability of a molecule to have energy greater than or equal to E at the given temperature T. This exponential dependence of a reaction rate on temperature is known as the Arrhenius equation . The activation energy necessary for a chemical reaction to occur can be in the form of heat, light, electricity or mechanical force in the form of ultrasound . A related concept free energy , which also incorporates entropy considerations,
3960-517: Is useful in identifying periodic trends . A compound is a pure chemical substance composed of more than one element. The properties of a compound bear little similarity to those of its elements. The standard nomenclature of compounds is set by the International Union of Pure and Applied Chemistry (IUPAC). Organic compounds are named according to the organic nomenclature system. The names for inorganic compounds are created according to
4070-529: The First Opium War , was signed in the city harbor on Royal Navy warships. As the capital of the brief-lived rebel Taiping Heavenly Kingdom in the mid-19th century, Nanjing was known as Tianjing ( 天京 ; 'Heavenly Capital" or "Capital of Heaven'). The rebellion destroyed most of the former Ming imperial buildings in the city, including the Porcelain Tower , considered up to that time as one of
4180-721: The International Military Tribunal for the Far East and the Nanjing War Crimes Tribunal after the atomic bombings, was between 300,000 and 350,000. The city itself was also severely damaged during the massacre. The Nanjing Massacre Memorial Hall was built in 1985 to commemorate this event. A few days before the fall of the city, the National Government of China was relocated to the southwestern city Chongqing and resumed Chinese resistance. In 1940,
4290-550: The Mongols ; during their rule as the Yuan dynasty , the city's status as a hub of the textile industry was further consolidated. According to Odoric of Pordenone , Chilenfu (Nanjing) had 360 stone bridges, which were finer than anywhere else in the world. It was well populated and had a large craft industry. After Zhu Yuanzhang (known from his era as the Hongwu Emperor ) overthrew
4400-945: The Nanjing Massacre from late 1937 to early 1938. Nanjing became the capital city of Jiangsu province in 1952, after serving as a Direct-administered Municipality from 1949 to 1952 following the establishment of the People's Republic of China. It has many important heritage sites, including the Presidential Palace , Sun Yat-sen Mausoleum and Ming Xiaoling Mausoleum . Nanjing is famous for human historical landscapes, mountains and waters such as Fuzimiao , Ming Palace , Chaotian Palace , Porcelain Tower , Drum Tower , Stone City , City Wall , Qinhuai River , Xuanwu Lake and Purple Mountain . Key cultural facilities include Nanjing Library , Nanjing Museum and Jiangsu Art Museum. The city has
4510-563: The Northern and Southern dynasties period. After the Eastern Jin fell in 420, it continued to serve as the capital for the Southern dynasties of Liu Song , Southern Qi , Liang and Chen . During this time, Jiankang was the international hub of East Asia. Based on historical documents, the city had 280,000 registered households. Assuming an average Nanjing household consisted of about 5.1 people,
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4620-577: The Qianlong Emperor , Jiangnan was fully divided into the present provinces of Anhui and Jiangsu . Separately, however, these provinces were reunited under the supervision of a new Viceroy of Liangjiang after 1723, whose seat was based in Jiangning. It was the site of a Qing Army garrison. It had been visited by the Kangxi and Qianlong emperors a number of times on their tours of the southern provinces. The 1842 Treaty of Nanking , which put an end to
4730-597: The Republic of China under the nationalist Kuomintang (1927–37, 1946–49) before its flight to Taiwan by Chiang Kai-Shek during the Chinese Civil War . The city also served as the seat of the rebel Taiping Heavenly Kingdom (1853–64) and the Japanese puppet regime of Wang Jingwei (1940–45) during the Second Sino-Japanese War . It suffered many notable devastating atrocities in both conflicts, most notably
4840-461: The Republic of China (1912–49) , jing ( 京 ; 'capital') was adopted as the abbreviation of Nanjing. Archaeological discovery shows that the so-called " Nanjing Man " lived more than 500,000 years ago. Zun , a kind of wine vessel, were found to exist in Beiyinyangying culture of Nanjing about 5000 years ago. About 7000 years ago, there was an agricultural civilization in the area that
4950-575: The Stone City at the site of Jinling Yi, and renamed Moling to Jianye. Jianye later became the capital of the Eastern Wu dynasty during the Three Kingdoms period, after Sun Quan proclaimed himself emperor in 229, opening Nanjing's history as a state capital. By the time Wu was conquered by the Western Jin dynasty in 280, Jianye and its neighboring areas had been well cultivated, developing into one of
5060-635: The Sui dynasty reunified China and almost destroyed the entire city, turning it into a small town. The city was razed after the Sui took it over. It was renamed Shengzhou ( 昇州 ) in the Tang dynasty and resuscitated during the late Tang. It was chosen as the capital and called Jinling ( 金陵 ) during the Southern Tang (937–976), which succeeded the state of Yang Wu . It was renamed Jiangning ( 江寧 , "Pacified Area of
5170-505: The Woodward–Hoffmann rules often come in handy while proposing a mechanism for a chemical reaction. According to the IUPAC gold book, a chemical reaction is "a process that results in the interconversion of chemical species." Accordingly, a chemical reaction may be an elementary reaction or a stepwise reaction . An additional caveat is made, in that this definition includes cases where
5280-735: The Yangtze ") in the Northern Song and renamed Jiankang in the Southern Song . Jiankang's textile industry burgeoned and thrived during the Song despite the constant threat of foreign invasions from the north by the Jurchen -led Jin dynasty . The court of Da Chu , a short-lived puppet state established by the Jurchens, and the court of Song were once in the city. The Southern Song were eventually destroyed by
5390-455: The chemical bonds which hold atoms together. Such behaviors are studied in a chemistry laboratory . The chemistry laboratory stereotypically uses various forms of laboratory glassware . However glassware is not central to chemistry, and a great deal of experimental (as well as applied/industrial) chemistry is done without it. A chemical reaction is a transformation of some substances into one or more different substances. The basis of such
5500-487: The chemical industry . The word chemistry comes from a modification during the Renaissance of the word alchemy , which referred to an earlier set of practices that encompassed elements of chemistry, metallurgy , philosophy , astrology , astronomy , mysticism , and medicine . Alchemy is often associated with the quest to turn lead or other base metals into gold, though alchemists were also interested in many of
5610-433: The duet rule , and in this way they are reaching the electron configuration of the noble gas helium , which has two electrons in its outer shell. Similarly, theories from classical physics can be used to predict many ionic structures. With more complicated compounds, such as metal complexes , valence bond theory is less applicable and alternative approaches, such as the molecular orbital theory, are generally used. In
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#17330849163355720-499: The inorganic nomenclature system. When a compound has more than one component, then they are divided into two classes, the electropositive and the electronegative components. In addition the Chemical Abstracts Service has devised a method to index chemical substances. In this scheme each chemical substance is identifiable by a number known as its CAS registry number . A molecule is the smallest indivisible portion of
5830-500: The interconversion of conformers is experimentally observable. Such detectable chemical reactions normally involve sets of molecular entities as indicated by this definition, but it is often conceptually convenient to use the term also for changes involving single molecular entities (i.e. 'microscopic chemical events'). An ion is a charged species, an atom or a molecule, that has lost or gained one or more electrons. When an atom loses an electron and thus has more protons than electrons,
5940-529: The intermolecular forces of a substance are such that the energy of the surroundings is not sufficient to overcome them, it occurs in a more ordered phase like liquid or solid as is the case with water (H 2 O); a liquid at room temperature because its molecules are bound by hydrogen bonds . Whereas hydrogen sulfide (H 2 S) is a gas at room temperature and standard pressure, as its molecules are bound by weaker dipole–dipole interactions . The transfer of energy from one chemical substance to another depends on
6050-587: The island of Taiwan on December 10 where Taipei was proclaimed the temporary capital of the Republic of China. By late 1949, the PLA was pursuing remnants of KMT forces southwards in southern China, and only Tibet and Hainan Island were left. After the establishment of the People's Republic of China in October 1949, Nanjing was initially a province-level municipality , but it was soon merged into Jiangsu and again became
6160-438: The size of energy quanta emitted from one substance. However, heat energy is often transferred more easily from almost any substance to another because the phonons responsible for vibrational and rotational energy levels in a substance have much less energy than photons invoked for the electronic energy transfer. Thus, because vibrational and rotational energy levels are more closely spaced than electronic energy levels, heat
6270-491: The world's third most prolific scientific research center in chemistry and physical sciences , according to the Nature Index . Nanjing, one of the nation's most important cities for over a thousand years, is recognized as one of the Four Great Ancient Capitals of China . It has been one of the world's largest cities , enjoying peace and prosperity despite various wars and disasters. Nanjing served as
6380-622: The Drum Tower Hospital and the boys' school would be expanded by later missionaries to become the University of Nanking and Medical School. The old mission property became the No. 13 Middle School, the oldest continually-used school grounds in the city. The Xinhai Revolution led to the founding of the Republic of China in January 1912 with Sun Yat-sen as the first provisional president and Nanjing
6490-562: The Manchus in late May 1645, the Hongguang Emperor fled Nanjing, and the imperial Ming Palace was looted by local residents. On June 6, Dodo's troops approached Nanjing, and the commander of the city's garrison, Zhao the Earl of Xincheng, promptly surrendered the city to them. The Manchus soon ordered all male residents of the city to shave their heads in the Manchu queue way . They requisitioned
6600-527: The Ming and Qing dynasties and earlier dynasties. On 9 June 2017, the Second Historical Archives of China opened to the public for the first time. Nanjing Nanjing is the capital of Jiangsu province in eastern China . The city, which is located in the southwestern corner of the province, has 11 districts, an administrative area of 6,600 km (2,500 sq mi), and as of 2021
6710-499: The Nanjing area. Hushu culture developed into Wu culture under the influence of the Shang and Zhou, who encroached from Central Plains. From the traditions, Taibo of Zhou came to Jiangnan and established the state of Wu during the 12th century BC. In 571 BC, the State of Chu established Tangyi in Liuhe. This is the oldest extant administrative establishment in Nanjing; as of 2024 it has
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#17330849163356820-513: The Qing to prepare for a final massive battle instead of swiftly attacking Nanjing. Koxinga's Ming loyalists fought against a majority Han Chinese Bannermen Qing army when attacking Nanjing. The siege lasted almost three weeks. Koxinga's forces were unable to maintain a complete encirclement, which enabled the city to obtain supplies and even reinforcements—though cavalry attacks by the city's forces were successful even before reinforcements arrived. Koxinga's forces were defeated and "slipped back" to
6930-840: The Republic of China, including archives of the Nanjing Provisional Government , the Guangzhou and Wuhan Nationalist Governments , the Beijing Government of the Republic of China , the Nanjing Nationalist Government , and the Wang Jingwei regime . The Second Historical Archives of China is in contrast to the First Historical Archives of China , which is responsible for collecting and managing archives formed by central government institutions during
7040-536: The Terrace empty, and the river flows on. Flourishing flowers of Wu Palace are buried beneath dark trails; Caps and gowns of Jin times all lie in ancient mounds. The Three-peaked Mountain lies half visible under the blue sky, The two-forked stream is separated by the White-Egret Isle in the middle. Clouds always block the sun, Chang'an cannot be seen and I grieve. The period of division ended when
7150-420: The Valence Shell Electron Pair Repulsion model ( VSEPR ), and the concept of oxidation number can be used to explain molecular structure and composition. An ionic bond is formed when a metal loses one or more of its electrons, becoming a positively charged cation, and the electrons are then gained by the non-metal atom, becoming a negatively charged anion. The two oppositely charged ions attract one another, and
7260-490: The Yongle Emperor was obliged to preserve its special status, at least in name. The "northern capital" came to be known as Beijing and the 'southern capital' as Nanjing ( 南京 ). Both controlled territories "directly administered" by the emperor and his staff, Beizhili in the north and Nanzhili in the south. The Hongxi Emperor wanted to restore Nanjing as the sole imperial capital and undertook preparations to do so. On February 24, 1425, he appointed Admiral Zheng He as
7370-408: The Yuan and established the Ming dynasty , he renamed the city Yingtian ( 應天 ) , rebuilt it, and made it the dynastic capital in 1368, overseeing the surrounding areas under a special administration. The Hongwu Emperor constructed a 48 km (30 mi) long city wall around Yingtian , as well as a new Ming Palace complex, and government halls. It took 200,000 laborers 21 years to finish
7480-446: The atom is a positively charged ion or cation . When an atom gains an electron and thus has more electrons than protons, the atom is a negatively charged ion or anion . Cations and anions can form a crystalline lattice of neutral salts , such as the Na and Cl ions forming sodium chloride , or NaCl. Examples of polyatomic ions that do not split up during acid–base reactions are hydroxide (OH ) and phosphate (PO 4 ). Plasma
7590-418: The capital of Eastern Wu (229–280), one of the three major states in the Three Kingdoms period; the Eastern Jin and each of the Southern dynasties ( Liu Song , Southern Qi , Liang and Chen ), which successively ruled southern China from 317 to 589; the Southern Tang (937–75), one of the Ten Kingdoms ; the Ming dynasty when, for the first time, all of China was ruled from the city (1368–1421); and
7700-408: The capital of the Republic of China, and this became internationally recognized once KMT forces took Beijing in 1928. The following decade is known as the Nanjing decade . During this decade, Nanjing was of symbolic and strategic importance. The Ming dynasty had made Nanjing a capital, the republic had been established there in 1912, and Sun Yat-sen 's provisional government had been there. Sun's body
7810-411: The changes they undergo during reactions with other substances . Chemistry also addresses the nature of chemical bonds in chemical compounds . In the scope of its subject, chemistry occupies an intermediate position between physics and biology . It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at
7920-515: The city or from superstitious fear of its geomantic properties . A monument to the huge human cost of some of the gigantic construction projects of the early Ming dynasty is the Yangshan Quarry (located some 15–20 km (9–12 mi) east of the walled city and Ming Xiaoling mausoleum), where a gigantic stele , cut on the orders of the Yongle Emperor, lies abandoned. As the center of
8030-603: The city had more than 1.4 million residents. A number of sculptural ensembles of that era, erected at the tombs of royals and other dignitaries, have survived (in various degrees of preservation) in Nanjing's northeastern and eastern suburbs, primarily in Qixia and Jiangning District . Possibly the best preserved of them is the ensemble of the Tomb of Xiao Xiu (475–518), a brother of Emperor Wu of Liang . The phoenix birds once frolicked on Phoenix Terrace, The birds are gone,
8140-498: The commercial, cultural and political centers of China. Not long after the unification of China, the Western Jin collapsed under the weight of civil wars by eight princes and rebellions from the so-called " Five Barbarians " in the north. Jianye, renamed to Jiankang in 313 to avoid Emperor Min of Jin's taboo name , was safely isolated from the chaos and became a popular refuge for the northern nobles and wealthy families. In 318,
8250-412: The context of chemistry, energy is an attribute of a substance as a consequence of its atomic , molecular or aggregate structure . Since a chemical transformation is accompanied by a change in one or more of these kinds of structures, it is invariably accompanied by an increase or decrease of energy of the substances involved. Some energy is transferred between the surroundings and the reactants of
8360-578: The defender of Nanjing and ordered him to continue his command over the Ming treasure fleet for the city's defense. Zheng He governed the city with three eunuchs for internal matters and two military noblemen for external matters, awaiting the Hongxi Emperor's return along with the military establishment from the north. The emperor died on May 29, 1425, before this could have taken place. The succeeding Xuande Emperor preferred to remain in Beijing, leaving it
8470-556: The empire, early-Ming Nanjing had worldwide connections. It was home of the admiral Zheng He , who went to sail the Pacific and Indian Oceans , and it was visited by foreign dignitaries, such as a king from Borneo ( 渤泥 ; Bóní ), who died during his visit to China in 1408. The Tomb of the King of Boni , with a spirit way and a tortoise stele , was discovered in Yuhuatai District (south of
8580-429: The energies and distributions characterize the availability of an electron to bond to another atom. The chemical bond can be a covalent bond , an ionic bond , a hydrogen bond or just because of Van der Waals force . Each of these kinds of bonds is ascribed to some potential. These potentials create the interactions which hold atoms together in molecules or crystals . In many simple compounds, valence bond theory ,
8690-444: The formation or dissociation of molecules, that is, molecules breaking apart to form two or more molecules or rearrangement of atoms within or across molecules. Chemical reactions usually involve the making or breaking of chemical bonds. Oxidation, reduction , dissociation , acid–base neutralization and molecular rearrangement are some examples of common chemical reactions. A chemical reaction can be symbolically depicted through
8800-431: The home to one of the world's largest inland ports . The city is also one of the fifteen sub-provincial cities in the People's Republic of China's administrative structure , enjoying jurisdictional and economic autonomy only slightly less than that of a province . It has also been awarded the title of 2008 Habitat Scroll of Honor of China, Special UN Habitat Scroll of Honor Award and National Civilized City. Nanjing
8910-447: The ionic bond is the electrostatic force of attraction between them. For example, sodium (Na), a metal, loses one electron to become an Na cation while chlorine (Cl), a non-metal, gains this electron to become Cl . The ions are held together due to electrostatic attraction, and that compound sodium chloride (NaCl), or common table salt, is formed. In a covalent bond, one or more pairs of valence electrons are shared by two atoms:
9020-401: The main characteristics of a molecule is its geometry often called its structure . While the structure of diatomic , triatomic or tetra-atomic molecules may be trivial, ( linear , angular pyramidal etc.) the structure of polyatomic molecules, that are constituted of more than six atoms (of several elements) can be crucial for its chemical nature. A chemical substance is a kind of matter with
9130-555: The most modern cities in China. In 1937, the Empire of Japan started a full-scale invasion of China after invading Manchuria in 1931, beginning the Second Sino-Japanese War (often considered a theater of World War II ). Their troops occupied Nanjing in December and carried out the systematic and brutal Nanjing Massacre (the "Rape of Nanjing"). The total death toll, including estimates made by
9240-419: The other isolated chemical elements consist of either molecules or networks of atoms bonded to each other in some way. Identifiable molecules compose familiar substances such as water, air, and many organic compounds like alcohol, sugar, gasoline, and the various pharmaceuticals . However, not all substances or chemical compounds consist of discrete molecules, and indeed most of the solid substances that make up
9350-496: The outskirts of the present-day Zhonghua Gate , which was the beginning of the construction of the main city of Nanjing. In 333 BC, Chu defeated Yue and built Jinling Yi ( 金陵邑 ) on in the western part of Nanjing. It was the earliest administrative construction in the main city of Nanjing. The name of Jinling comes from this. In 210 BC, the First Emperor of Qin visited the east and changed Jinling City to Moling ( 秣陵 ). The area
9460-485: The primary and de facto capital and Nanjing as permanent secondary or reserve capital. Owing to the continuing importance of the ancestral injunctions , however, Nanjing was designated in official documents as the actual capital and Beijing as a temporary capital from 1425 to 1441. In 1441, the Yingzong Emperor ordered the "provisional" ( 行在 ) prefix removed from Beijing's government seals and further ordered that
9570-443: The provincial capital by replacing Zhenjiang which was transferred in 1928, and retains that status to this day. Chemistry Chemistry is the scientific study of the properties and behavior of matter . It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms , molecules and ions : their composition, structure, properties, behavior and
9680-615: The questions of modern chemistry. The modern word alchemy in turn is derived from the Arabic word al-kīmīā ( الكیمیاء ). This may have Egyptian origins since al-kīmīā is derived from the Ancient Greek χημία , which is in turn derived from the word Kemet , which is the ancient name of Egypt in the Egyptian language. Alternately, al-kīmīā may derive from χημεία 'cast together'. The current model of atomic structure
9790-473: The reaction absorbs heat from the surroundings. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy . The speed of a chemical reaction (at given temperature T) is related to the activation energy E, by the Boltzmann's population factor e − E / k T {\displaystyle e^{-E/kT}} – that
9900-433: The reaction in the form of heat or light ; thus the products of a reaction may have more or less energy than the reactants. A reaction is said to be exergonic if the final state is lower on the energy scale than the initial state; in the case of endergonic reactions the situation is the reverse. A reaction is said to be exothermic if the reaction releases heat to the surroundings; in the case of endothermic reactions ,
10010-544: The resulting electrically neutral group of bonded atoms is termed a molecule . Atoms will share valence electrons in such a way as to create a noble gas electron configuration (eight electrons in their outermost shell) for each atom. Atoms that tend to combine in such a way that they each have eight electrons in their valence shell are said to follow the octet rule . However, some elements like hydrogen and lithium need only two electrons in their outermost shell to attain this stable configuration; these atoms are said to follow
10120-403: The rules of quantum mechanics , which require quantization of energy of a bound system. The atoms/molecules in a higher energy state are said to be excited. The molecules/atoms of substance in an excited energy state are often much more reactive; that is, more amenable to chemical reactions. The phase of a substance is invariably determined by its energy and the energy of its surroundings. When
10230-580: The ruling prince in Jiankang, Sima Rui proclaimed himself the new emperor and reestablished the dynasty as the Eastern Jin dynasty . This marked the first time a Chinese dynastic capital was moved from the north to southern China , as the north came under the rule of the Sixteen Kingdoms . Jiankang was the centre of administration in the south for more than two and a half centuries, even as China entered
10340-474: The same mass number; atoms of an element which have different mass numbers are known as isotopes . For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbon , but atoms of carbon may have mass numbers of 12 or 13. The standard presentation of the chemical elements is in the periodic table , which orders elements by atomic number. The periodic table is arranged in groups , or columns, and periods , or rows. The periodic table
10450-577: The ships which had brought them. Under the Qing dynasty from 1645 to 1911, Nanjing returned to its previous name Jiangning . At first, it continued to administer the territory of Nanzhili under the name Jiangnan ("Area South of the Yangtze") but this administration was soon broken up into "Right" and "Left" governments based in Suzhou and Jiangning respectively. After a series of reorganizations, at some point under
10560-641: The solid crust, mantle, and core of the Earth are chemical compounds without molecules. These other types of substances, such as ionic compounds and network solids , are organized in such a way as to lack the existence of identifiable molecules per se . Instead, these substances are discussed in terms of formula units or unit cells as the smallest repeating structure within the substance. Examples of such substances are mineral salts (such as table salt ), solids like carbon and diamond, metals, and familiar silica and silicate minerals such as quartz and granite. One of
10670-450: The southern imperial administration would henceforth be required to prefix "Nanjing" to their own seals to distinguish them. Besides the city wall, other Ming-era structures in the city included the famous Ming Xiaoling Mausoleum and Porcelain Tower , although the latter was destroyed by the Taipings in the 19th century either to prevent a hostile faction from using it to observe and shell
10780-411: The spelling as "Nanjing". During the Qing dynasty , the city was called Jiangning ( 江寧 ; Kiang-ning ), whose first character jiang ( Chinese : 江 ; pinyin : jiāng ; lit. 'river', i.e. the Yangtze ) is the former part of the name Jiangsu and second character ning ( 寧 , simplified form 宁 ; 'peace') is the shortened name of Nanjing. When it was the capital of
10890-695: The structure of the system, instead of changing the bulk conditions. Sometimes the distinction between phases can be continuous instead of having a discrete boundary; in this case the matter is considered to be in a supercritical state. When three states meet based on the conditions, it is known as a triple point and since this is invariant, it is a convenient way to define a set of conditions. The most familiar examples of phases are solids , liquids , and gases . Many substances exhibit multiple solid phases. For example, there are three phases of solid iron (alpha, gamma, and delta) that vary based on temperature and pressure. A principal difference between solid phases
11000-421: The study of chemistry; some of them are: In chemistry, matter is defined as anything that has rest mass and volume (it takes up space) and is made up of particles . The particles that make up matter have rest mass as well – not all particles have rest mass, such as the photon . Matter can be a pure chemical substance or a mixture of substances. The atom is the basic unit of chemistry. It consists of
11110-410: The wall, which was intended to defend the city and its surrounding region from coastal pirates. The present-day City Wall of Nanjing was mainly built during that time and today it remains in good condition and has been well preserved. It is among the longest surviving city walls in China. The Jianwen Emperor ruled from Yingtian from 1398 to 1402. It is believed that Nanjing was the largest city in
11220-477: The walled city) in 1958, and has been restored. Over two centuries after the removal of the capital to Beijing, Nanjing was destined to become the capital of a Ming emperor one more time. After the fall of Beijing to Li Zicheng 's rebel forces and then to the Manchu -led Qing dynasty in the spring of 1644, the Ming prince Zhu Yousong was enthroned in Nanjing in June 1644 as the Hongguang Emperor. His short reign
11330-544: The wonders of the world. Both the Qing viceroy and the Taiping king resided in buildings that would later be known as the Presidential Palace . When Qing forces led by Zeng Guofan retook the city in 1864, a massive slaughter occurred in the city with over 100,000 estimated to have committed suicide or fought to the death. Since the Taiping Rebellion began, Qing forces allowed no rebels speaking its dialect to surrender. This
11440-584: The world from 1358 to 1425 with a population of 487,000 in 1400. Having usurped power from his nephew and uncertain of the loyalty of the region's officials, the Yongle Emperor relocated the capital in 1421 to Beijing, where he had long served as the regional governor as the Prince of Yan . Because the new status of Yingtian was included in the Hongwu Emperor's " ancestral injunctions " for his dynasty, however,
11550-707: Was brought and placed in a grand mausoleum to cement Chiang's legitimacy. Chiang was born in the neighboring province of Zhejiang and the general area had strong popular support for him. In 1927, the Nationalist government proposed a comprehensive planning proposal, the Capital Plan ( 首都計劃 ), to reconstruct the war-torn city of Nanjing into a modern capital. It was a decade of extraordinary growth with an enormous amount of construction. A lot of government buildings, residential houses, and modern public infrastructures were built. During this boom, Nanjing reputedly became one of
11660-460: Was described by later historians as the first reign of the so-called Southern Ming dynasty . Zhu Yousong, however, fared a lot worse than his ancestor Zhu Yuanzhang three centuries earlier. Beset by factional conflicts, his regime could not offer effective resistance to Qing forces, when the Qing army, led by the Manchu prince Dodo approached Jiangnan the next spring. Days after Yangzhou fell to
11770-533: Was one of two historically significant instances of systematic civilian massacres in Nanjing, the other one was the Houjing Disturbance of the 6th century. The New York Methodist Mission Society's superintendent Virgil Hart arrived in Nanjing in 1881. After some time, he succeeded in buying land near the city's Southern Gate and Confucian Temple to build the city's first Methodist church, Western hospital and boys' school. The hospital would later be unified with
11880-404: Was renamed Jiankang . Nanjing is also called Jincheng ( 金城 , Golden City), derived from Jinling City. The name Nanjing , which means "southern capital", was officially designated for the city during the Ming dynasty , about six hundred years later. In English, the spelling Nanking was traditional until pinyin , developed in the 1950s and internationally adopted in the 1980s, standardized
11990-529: Was selected as its new capital. However, the Qing Empire controlled large regions to the north, so the revolutionaries asked Yuan Shikai to replace Sun as president in exchange for the abdication of Puyi , the last emperor. Yuan demanded the capital be moved to Beijing (closer to his power base). In 1927, the Kuomintang (KMT; Nationalist Party) under Generalissimo Chiang Kai-shek again established Nanjing as
12100-526: Was successively part of Kuaiji , Zhang and Danyang prefectures in Qin and Han dynasty, and part of Yangzhou region which was established as the nation's 13 supervisory and administrative regions in the 5th year of Yuanfeng in Han dynasty (106 BC). Nanjing was later the capital city of Danyang Prefecture, and had been the capital city of Yangzhou for about 400 years from late Han to early Tang . Six Dynasties
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