97-599: The Physical and Theoretical Chemistry Laboratory ( PTCL ) is a major chemistry laboratory at the University of Oxford , England . It is located in the main Science Area of the university on South Parks Road . Previously it was known as the Physical Chemistry Laboratory . The original Physical Chemistry Laboratory was built in 1941 and at that time also housed the inorganic chemistry laboratory. It replaced
194-440: 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
291-742: A literary language , and was also the language of the New Kingdom administration. Texts written wholly in Late Egyptian date to the Twentieth Dynasty of Egypt and later. Late Egyptian is represented by a large body of religious and secular literature , comprising such examples as the Story of Wenamun , the love poems of the Chester–Beatty I papyrus, and the Instruction of Any . Instructions became
388-566: A synthetic language , Egyptian by the Late Egyptian phase had become an analytic language . The relationship between Middle Egyptian and Late Egyptian has been described as being similar to that between Latin and Italian. The Late Egyptian stage is taken to have ended around the 8th century BC, giving rise to Demotic. Demotic is a later development of the Egyptian language written in the Demotic script , following Late Egyptian and preceding Coptic ,
485-467: 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
582-470: 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
679-402: 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
776-412: 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
873-541: 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
970-550: A few have survived that were written in hieratic and (later) demotic. There was also a form of cursive hieroglyphs , used for religious documents on papyrus, such as the Book of the Dead of the Twentieth Dynasty ; it was simpler to write than the hieroglyphs in stone inscriptions, but it was not as cursive as hieratic and lacked the wide use of ligatures . Additionally, there was a variety of stone-cut hieratic, known as "lapidary hieratic". In
1067-488: A few specialists in the language. For all other purposes, the Egyptological pronunciation is used, but it often bears little resemblance to what is known of how Egyptian was pronounced. The following consonants are reconstructed for Archaic (before 2600 BC) and Old Egyptian (2686–2181 BC), with IPA equivalents in square brackets if they differ from the usual transcription scheme: / l / has no independent representation in
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#17330857659201164-411: 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
1261-442: A popular literary genre of the New Kingdom, which took the form of advice on proper behavior. Late Egyptian was also the language of New Kingdom administration. Late Egyptian is not completely distinct from Middle Egyptian, as many "classicisms" appear in historical and literary documents of this phase. However, the difference between Middle and Late Egyptian is greater than the difference between Middle and Old Egyptian. Originally
1358-493: A positive hydrogen ion to another substance in a chemical reaction; by extension, a base is the substance which receives that hydrogen ion. Egyptian language The Egyptian language , or Ancient Egyptian ( r n kmt ; "speech of Egypt") is an extinct branch of the Afro-Asiatic languages that was spoken in ancient Egypt . It is known today from a large corpus of surviving texts, which were made accessible to
1455-405: 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
1552-444: A scribe jokes that his colleague's writing is incoherent like "the speech of a Delta man with a man of Elephantine ." Recently, some evidence of internal dialects has been found in pairs of similar words in Egyptian that, based on similarities with later dialects of Coptic, may be derived from northern and southern dialects of Egyptian. Written Coptic has five major dialects, which differ mainly in graphic conventions, most notably
1649-496: A stressed vowel (⟨ bjn ⟩ = */ˈbaːjin/ 'bad') and as ⟨ jj ⟩ word-medially immediately before a stressed vowel ( ⟨ḫꜥjjk⟩ = */χaʕˈjak/ 'you will appear') and are unmarked word-finally (⟨ jt ⟩ = /ˈjaːtVj/ 'father'). In Middle Egyptian (2055–1650 BC), a number of consonantal shifts take place. By the beginning of the Middle Kingdom period, / z / and / s / had merged, and
1746-502: A stressed vowel in syllables that had been closed in earlier Egyptian (compare ⲛⲟⲩⲃ < */ˈnaːbaw/ 'gold' and ⲧⲁⲡ < * /dib/ 'horn'). The phonemes /d g z/ occur only in Greek loanwords, with rare exceptions triggered by a nearby /n/ : ⲁⲛⲍⲏⲃⲉ/ⲁⲛⲥⲏⲃⲉ < ꜥ.t n.t sbꜣ.w 'school'. Earlier *d ḏ g q are preserved as ejective t' c' k' k ' before vowels in Coptic. Although
1843-609: 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
1940-634: A transliteration of the corresponding Demotic "alphabetical" sign(s) in angle brackets ⟨ ⟩ . More changes occur in the 1st millennium BC and the first centuries AD, leading to Coptic (1st or 3rd – c. 19th centuries AD). In Sahidic ẖ ḫ ḥ had merged into ϣ š (most often from ḫ ) and ϩ / h / (most often ẖ ḥ ). Bohairic and Akhmimic are more conservative and have a velar fricative / x / ( ϧ in Bohairic, ⳉ in Akhmimic). Pharyngeal *ꜥ had merged into glottal / ʔ / after it had affected
2037-461: A uniliteral hieroglyph. Egyptian scholar Gamal Mokhtar noted that the inventory of hieroglyphic symbols derived from "fauna and flora used in the signs [which] are essentially African", reflecting the local wildlife of North Africa, the Levant and southern Mediterranean. In "regards to writing, we have seen that a purely Nilotic, hence [North] African origin not only is not excluded, but probably reflects
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#17330857659202134-414: 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
2231-409: 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
2328-582: 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
2425-422: 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,
2522-439: 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,
2619-526: 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
2716-470: Is dated from the oldest known complete sentence, including a finite verb , which has been found. Discovered in the tomb of Seth-Peribsen (dated c. 2690 BC ), the seal impression reads: Extensive texts appear from about 2600 BC. An early example is the Diary of Merer . The Pyramid Texts are the largest body of literature written in this phase of the language. One of its distinguishing characteristics
2813-472: 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
2910-464: 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
3007-641: 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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3104-551: 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
3201-539: 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
3298-449: Is not a contrastive feature; all obstruents are voiceless and all sonorants are voiced. Stops may be either aspirated or tenuis (unaspirated), although there is evidence that aspirates merged with their tenuis counterparts in certain environments. The following table presents the consonants of Demotic Egyptian. The reconstructed value of a phoneme is given in IPA transcription, followed by
3395-399: Is sometimes reserved for the earliest use of hieroglyphs, from the late fourth through the early third millennia BC. At the earliest stage, around 3300 BC, hieroglyphs were not a fully developed writing system , being at a transitional stage of proto-writing ; over the time leading up to the 27th century BC, grammatical features such as nisba formation can be seen to occur. Old Egyptian
3492-468: 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
3589-458: 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
3686-424: Is the best-documented variety of the language, and has attracted the most attention by far from Egyptology . While most Middle Egyptian is seen written on monuments by hieroglyphs, it was also written using a cursive variant , and the related hieratic . Middle Egyptian first became available to modern scholarship with the decipherment of hieroglyphs in the early 19th century. The first grammar of Middle Egyptian
3783-502: 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,
3880-453: 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 the changes they undergo during reactions with other substances . Chemistry also addresses the nature of chemical bonds in chemical compounds . In
3977-406: Is the tripling of ideograms , phonograms, and determinatives to indicate the plural. Overall, it does not differ significantly from Middle Egyptian, the classical stage of the language, though it is based on a different dialect. In the period of the 3rd dynasty ( c. 2650 – c. 2575 BC ), many of the principles of hieroglyphic writing were regularized. From that time on, until
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4074-517: 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
4171-527: The Balliol-Trinity Laboratories . The east wing of the building was completed in 1959 and inorganic chemistry, already in its own building on South Parks Road , then became a separate department in 1961. In 1972, the Department of Theoretical Chemistry was established in a house on South Parks Road, and in 1994, the amalgamation of the physical and theoretical chemistry departments took place. This
4268-551: The Coptic Catholic Church . Most hieroglyphic Egyptian texts are written in a literary prestige register rather than the vernacular speech variety of their author. As a result, dialectical differences are not apparent in written Egyptian until the adoption of the Coptic alphabet . Nevertheless, it is clear that these differences existed before the Coptic period. In one Late Egyptian letter (dated c. 1200 BC ),
4365-505: 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
4462-455: 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
4559-487: 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
4656-433: 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
4753-573: The hieroglyphic and hieratic scripts. Demotic is the name of the script derived from the hieratic beginning in the 7th century BC. The Coptic alphabet was derived from the Greek alphabet , with adaptations for Egyptian phonology. It was first developed in the Ptolemaic period , and gradually replaced the Demotic script in about the 4th to 5th centuries of the Christian era. The term "Archaic Egyptian"
4850-499: 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
4947-500: 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,
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#17330857659205044-529: 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
5141-574: The liturgical language of the Coptic Church . The Egyptian language branch belongs to the Afroasiatic language family . Among the typological features of Egyptian that are typically Afroasiatic are its fusional morphology, nonconcatenative morphology , a series of emphatic consonants , a three-vowel system /a i u/ , a nominal feminine suffix * -at , a nominal prefix m- , an adjectival suffix -ī and characteristic personal verbal affixes. Of
5238-438: 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
5335-553: The vernacular of the Middle Kingdom of Egypt and remained the literary language of Egypt until the Roman period . By the time of classical antiquity , the spoken language had evolved into Demotic , and by the Roman era , diversified into various Coptic dialects . These were eventually supplanted by Arabic after the Muslim conquest of Egypt , although Bohairic Coptic remains in use as
5432-592: The Semitic preference for triradical roots. Egyptian is probably more conservative, and Semitic likely underwent later regularizations converting roots into the triradical pattern. Although Egyptian is the oldest Afroasiatic language documented in written form, its morphological repertoire is very different from that of the rest of the Afroasiatic languages in general, and Semitic languages in particular. There are multiple possibilities: perhaps Egyptian had already undergone radical changes from Proto-Afroasiatic before it
5529-500: 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
5626-491: 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
5723-465: The cognate sets between Egyptian and Afroasiatic, the traditional theory and the neuere Komparatistik , founded by Semiticist Otto Rössler. According to the neuere Komparatistik , in Egyptian, the Proto-Afroasiatic voiced consonants */d z ð/ developed into pharyngeal ⟨ꜥ⟩ /ʕ/ : Egyptian ꜥr.t 'portal', Semitic dalt 'door'. The traditional theory instead disputes
5820-412: 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
5917-637: The emphatic consonants were realised is unknown. Early research had assumed that the opposition in stops was one of voicing, but it is now thought to be either one of tenuis and emphatic consonants , as in many Semitic languages, or one of aspirated and ejective consonants , as in many Cushitic languages . Since vowels were not written until Coptic, reconstructions of the Egyptian vowel system are much more uncertain and rely mainly on evidence from Coptic and records of Egyptian words, especially proper nouns, in other languages/writing systems. The actual pronunciations reconstructed by such means are used only by
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#17330857659206014-439: The end of a stressed syllable and eventually null word-finally: ⟨pḏ.t⟩ */ˈpiːɟat/ > Akkadian transcription -pi-ta 'bow'. The most important source of information about Demotic phonology is Coptic. The consonant inventory of Demotic can be reconstructed on the basis of evidence from the Coptic dialects. Demotic orthography is relatively opaque . The Demotic "alphabetical" signs are mostly inherited from
6111-429: 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 ,
6208-532: The first known Coptic text, still pagan ( Old Coptic ), from the 1st century AD. Coptic survived into the medieval period, but by the 16th century was dwindling rapidly due to the persecution of Coptic Christians under the Mamluks . It probably survived in the Egyptian countryside as a spoken language for several centuries after that. Coptic survives as the liturgical language of the Coptic Orthodox Church and
6305-444: 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
6402-655: The graphemes ⟨s⟩ and ⟨z⟩ are used interchangeably. In addition, / j / had become / ʔ / word-initially in an unstressed syllable (⟨ jwn ⟩ /jaˈwin/ > */ʔaˈwin/ "colour") and after a stressed vowel ( ⟨ḥjpw⟩ */ˈħujpVw/ > /ˈħeʔp(Vw)/ '[the god] Apis'). In Late Egyptian (1069–700 BC), the phonemes d ḏ g gradually merge with their counterparts t ṯ k ( ⟨dbn⟩ */ˈdiːban/ > Akkadian transcription ti-ba-an 'dbn-weight'). Also, ṯ ḏ often become /t d/ , but they are retained in many lexemes ; ꜣ becomes / ʔ / ; and /t r j w/ become / ʔ / at
6499-435: The hieroglyphic orthography, and it is frequently written as if it were / n / or / r / . That is probably because the standard for written Egyptian is based on a dialect in which / l / had merged with other sonorants. Also, the rare cases of / ʔ / occurring are not represented. The phoneme / j / is written as ⟨ j ⟩ in the initial position (⟨ jt ⟩ = */ˈjaːtVj/ 'father') and immediately after
6596-519: The hieroglyphic script, and due to historical sound changes they do not always map neatly onto Demotic phonemes . However, the Demotic script does feature certain orthographic innovations, such as the use of the sign h̭ for / ç /, which allow it to represent sounds that were not present in earlier forms of Egyptian. The Demotic consonants can be divided into two primary classes: obstruents ( stops , affricates and fricatives ) and sonorants ( approximants , nasals , and semivowels ). Voice
6693-447: 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:
6790-464: The language's final stage of development, the Coptic alphabet replaced the older writing system. Hieroglyphs are employed in two ways in Egyptian texts: as ideograms to represent the idea depicted by the pictures and, more commonly, as phonograms to represent their phonetic value. As the phonetic realization of Egyptian cannot be known with certainty, Egyptologists use a system of transliteration to denote each sound that could be represented by
6887-406: The latter of which it shares much with. In the earlier stages of Demotic, such as those texts written in the early Demotic script, it probably represented the spoken idiom of the time. However, as its use became increasingly confined to literary and religious purposes, the written language diverged more and more from the spoken form, leading to significant diglossia between the late Demotic texts and
6984-401: 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
7081-403: The modern world following the decipherment of the ancient Egyptian scripts in the early 19th century. Egyptian is one of the earliest known written languages , first recorded in the hieroglyphic script in the late 4th millennium BC . It is also the longest-attested human language, with a written record spanning over 4,000 years. Its classical form, known as " Middle Egyptian ," served as
7178-465: The other Afroasiatic branches, linguists have variously suggested that the Egyptian language shares its greatest affinities with Berber and Semitic languages, particularly Arabic (which is spoken in Egypt today) and Hebrew . However, other scholars have argued that the Egyptian language shared closer linguistic ties with northeastern African regions. There are two theories that seek to establish
7275-419: 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
7372-503: The quality of the surrounding vowels. / ʔ / is not indicated orthographically unless it follows a stressed vowel; then, it is marked by doubling the vowel letter (except in Bohairic): Akhmimic ⳉⲟⲟⲡ /xoʔp/ , Sahidic and Lycopolitan ϣⲟⲟⲡ šoʔp , Bohairic ϣⲟⲡ šoʔp 'to be' < ḫpr.w * /ˈχapraw/ 'has become'. The phoneme ⲃ / b / was probably pronounced as a fricative [ β ] , becoming ⲡ / p / after
7469-564: 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
7566-473: 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
7663-433: 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 ,
7760-861: The reality" that the geographical location of Egypt is, of course, in Africa. While the consonantal phonology of the Egyptian language may be reconstructed, the exact phonetics is unknown, and there are varying opinions on how to classify the individual phonemes. In addition, because Egyptian is recorded over a full 2,000 years, the Archaic and Late stages being separated by the amount of time that separates Old Latin from Modern Italian , significant phonetic changes must have occurred during that lengthy time frame. Phonologically, Egyptian contrasted labial, alveolar, palatal, velar, uvular, pharyngeal, and glottal consonants. Egyptian also contrasted voiceless and emphatic consonants, as with other Afroasiatic languages, but exactly how
7857-544: 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
7954-403: 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
8051-599: The same graphemes are used for the pulmonic stops ( ⟨ ⲧ ϫ ⲕ ⟩ ), the existence of the former may be inferred because the stops ⟨ ⲡ ⲧ ϫ ⲕ ⟩ /p t c k/ are allophonically aspirated [pʰ tʰ cʰ kʰ] before stressed vowels and sonorant consonants. In Bohairic, the allophones are written with the special graphemes ⟨ ⲫ ⲑ ϭ ⲭ ⟩ , but other dialects did not mark aspiration: Sahidic ⲡⲣⲏ , Bohairic ⲫⲣⲏ 'the sun'. Thus, Bohairic does not mark aspiration for reflexes of older *d ḏ g q : Sahidic and Bohairic ⲧⲁⲡ */dib/ 'horn'. Also,
8148-474: 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
8245-408: 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 a fundamental level. For example, chemistry explains aspects of plant growth ( botany ), the formation of igneous rocks ( geology ), how atmospheric ozone
8342-433: The script was supplanted by an early version of Coptic (about the third and fourth centuries), the system remained virtually unchanged. Even the number of signs used remained constant at about 700 for more than 2,000 years. Middle Egyptian was spoken for about 700 years, beginning around 2000 BC, during the Middle Kingdom and the subsequent Second Intermediate Period . As the classical variant of Egyptian, Middle Egyptian
8439-641: 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
8536-473: The southern Saidic dialect, the main classical dialect, and the northern Bohairic dialect, currently used in Coptic Church services. Most surviving texts in the Egyptian language are written on stone in hieroglyphs . The native name for Egyptian hieroglyphic writing is zẖꜣ n mdw-nṯr ("writing of the gods' words"). In antiquity, most texts were written on the quite perishable medium of papyrus though
8633-601: The spoken language of the time, similar to the use of classical Middle Egyptian during the Ptolemaic Period. Coptic is the name given to the late Egyptian vernacular when it was written in a Greek-based alphabet, the Coptic alphabet; it flourished from the time of Early Christianity (c. 31/33–324) , but Egyptian phrases written in the Greek alphabet first appeared during the Hellenistic period c. 3rd century BC , with
8730-695: 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
8827-421: 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
8924-644: The values given to those consonants by the neuere Komparatistik , instead connecting ⟨ꜥ⟩ with Semitic /ʕ/ and /ɣ/ . Both schools agree that Afroasiatic */l/ merged with Egyptian ⟨n⟩ , ⟨r⟩ , ⟨ꜣ⟩ , and ⟨j⟩ in the dialect on which the written language was based, but it was preserved in other Egyptian varieties. They also agree that original */k g ḳ/ palatalise to ⟨ṯ j ḏ⟩ in some environments and are preserved as ⟨k g q⟩ in others. The Egyptian language has many biradical and perhaps monoradical roots, in contrast to
9021-487: Was followed shortly by the theoretical group moving into the PTCL annexe in 1995. The university is in the early planning stages of the demolition of the PTCL building, to be replaced by a second chemistry research laboratory. The following Oxford Physical and Theoretical chemists are of note: This article about a scientific organization is a stub . You can help Misplaced Pages by expanding it . Chemistry Chemistry
9118-428: Was published by Adolf Erman in 1894, surpassed in 1927 by Alan Gardiner 's work. Middle Egyptian has been well-understood since then, although certain points of the verbal inflection remained open to revision until the mid-20th century, notably due to the contributions of Hans Jakob Polotsky . The Middle Egyptian stage is taken to have ended around the 14th century BC, giving rise to Late Egyptian. This transition
9215-473: Was recorded; or the Afroasiatic family has so far been studied with an excessively Semitocentric approach; or, as G. W. Tsereteli suggests, Afroasiatic is a sprachbund , rather than a true genetic language family. The Egyptian language can be grouped thus: The Egyptian language is conventionally grouped into six major chronological divisions: Old, Middle, and Late Egyptian were all written using both
9312-515: Was taking place in the later period of the Eighteenth Dynasty of Egypt (known as the Amarna Period ). Original Old Egyptian and Middle Egyptian texts were still used after the 14th century BCE. And an emulation of predominately Middle Egyptian, but also with characteristics of Old Egyptian, Late Egyptian and Demotic, called " Égyptien de tradition " or "Neo-Middle Egyptian" by scholars,
9409-592: Was used as a literary language for new texts since the later New Kingdom in official and religious hieroglyphic and hieratic texts in preference to Late Egyptian or Demotic. Égyptien de tradition as a religious language survived until the Christianisation of Roman Egypt in the 4th century. Late Egyptian was spoken for about 650 years, beginning around 1350 BC, during the New Kingdom of Egypt . Late Egyptian succeeded but did not fully supplant Middle Egyptian as
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