Jacobus Henricus van 't Hoff
Jacobus Henricus "Henry" van't Hoff, Jr. was a Dutch physical chemist. A influential theoretical chemist of his time, van't Hoff was the first winner of the Nobel Prize in Chemistry, his pioneering work helped found the modern theory of chemical affinity, chemical equilibrium, chemical kinetics, chemical thermodynamics. In his 1874 pamphlet van't Hoff formulated the theory of the tetrahedral carbon atom and laid the foundations of stereochemistry. In 1875, he predicted the correct structures of allenes and cumulenes as well as their axial chirality, he is widely considered one of the founders of physical chemistry as the discipline is known today. The third of seven children, van't Hoff was born in Rotterdam, Netherlands, 30 August 1852, his father was Jacobus Henricus van't Hoff, Sr. a physician, his mother was Alida Kolff van't Hoff. From a young age, he was interested in science and nature, took part in botanical excursions. In his early school years, he showed a strong interest in philosophy.
He considered Lord Byron to be his idol. Against the wishes of his father, van't Hoff chose to study chemistry. First, he enrolled at Delft University of Technology in September 1869, studied until 1871, when he passed his final exam on 8 July and obtained a degree of chemical technologist, he passed all his courses in two years. He enrolled at University of Leiden to study chemistry, he studied in Bonn, with Friedrich Kekulé and in Paris with C. A. Wurtz, he received his doctorate under Eduard Mulder at the University of Utrecht in 1874. In 1878, van't Hoff married Johanna Francina Mees, they had two daughters, Johanna Francina and Aleida Jacoba, two sons, Jacobus Henricus van't Hoff III and Govert Jacob. Van't Hoff died on 1 March 1911, at Steglitz, near Berlin, of tuberculosis. Van't Hoff earned his earliest reputation in the field of organic chemistry. In 1874, he accounted for the phenomenon of optical activity by assuming that the chemical bonds between carbon atoms and their neighbors were directed towards the corners of a regular tetrahedron.
This three-dimensional structure accounted for the isomers found in nature. He shares credit for this with the French chemist Joseph Le Bel, who independently came up with the same idea. Three months before his doctoral degree was awarded, van't Hoff published this theory, which today is regarded as the foundation of stereochemistry, first in a Dutch pamphlet in the fall of 1874, in the following May in a small French book entitled La chimie dans l'espace. A German translation appeared in 1877, at a time when the only job van't Hoff could find was at the Veterinary School in Utrecht. In these early years his theory was ignored by the scientific community, was criticized by one prominent chemist, Hermann Kolbe. Kolbe wrote: "A Dr. J. H. van ’t Hoff of the Veterinary School at Utrecht has no liking for exact chemical investigation. He has considered it more convenient to mount Pegasus and to proclaim in his ‘La chimie dans l’espace’ how, in his bold flight to the top of the chemical Parnassus, the atoms appeared to him to be arranged in cosmic space."
However, by about 1880 support for van't Hoff's theory by such important chemists as Johannes Wislicenus and Viktor Meyer brought recognition. In 1884, van't Hoff published his research on chemical kinetics, titled Études de Dynamique chimique, in which he described a new method for determining the order of a reaction using graphics and applied the laws of thermodynamics to chemical equilibria, he introduced the modern concept of chemical affinity. In 1886, he showed a similarity between the behaviour of dilute gases. In 1887, he and German chemist Wilhelm Ostwald founded an influential scientific magazine named Zeitschrift für physikalische Chemie, he worked on Svante Arrhenius's theory of the dissociation of electrolytes and in 1889 provided physical justification for the Arrhenius equation. In 1896, he became a professor at the Prussian Academy of Sciences in Berlin, his studies of the salt deposits at Stassfurt were an important contribution to Prussia's chemical industry. Van't Hoff became a lecturer in physics at the Veterinary College in Utrecht.
He worked as a professor of chemistry and geology at the University of Amsterdam for 18 years before becoming the chairman of the chemistry department. In 1896, van't Hoff moved to Germany, where he finished his career at the University of Berlin in 1911. In 1901, he received the first Nobel Prize in Chemistry for his work with solutions, his work showed that dilute solutions follow mathematical laws that resemble the laws describing the behavior of gases. In 1885, van't Hoff was appointed as a member of the Royal Netherlands Academy of Sciences. Other distinctions include honorary doctorates from Harvard and Yale, Victoria University, the University of Manchester, University of Heidelberg, he was awarded the Davy Medal of the Royal Society in 1893, elected a Foreign Member of the Royal Society in 1897. He was awarded the Helmholtz Medal of the Prussian Academy of Sciences and appointed Chevalier de la Légion d'honneur and Senator der Kaiser-Wilhelm-Gesellschaft. Van't Hoff became an honorary member of the British Chemical Society in London, the Royal Dutch Academy of Sciences, American Chemical Society, Borlase's Chemistry Society.
And the Académie des Scienc
In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation. See polarization and plane of polarization for more information; the orientation of a linearly polarized electromagnetic wave is defined by the direction of the electric field vector. For example, if the electric field vector is vertical the radiation is said to be vertically polarized; the classical sinusoidal plane wave solution of the electromagnetic wave equation for the electric and magnetic fields is E =∣ E ∣ R e B = z ^ × E / c for the magnetic field, where k is the wavenumber, ω = c k is the angular frequency of the wave, c is the speed of light. Here ∣ E ∣ is the amplitude of the field and | ψ ⟩ = d e f = is the Jones vector in the x-y plane; the wave is linearly polarized when the phase angles α x, α y are equal, α x = α y = d e f α. This represents. In that case, the Jones vector can be written | ψ ⟩ = exp .
The state vectors for linear polarization in x or y are special cases of this state vector. If unit vectors are defined such that | x ⟩ = d e f and | y ⟩ = d e f the polarization state can be written in the "x-y basis" as | ψ ⟩ = cos θ exp | x ⟩ + sin θ exp | y ⟩ = ψ x | x ⟩ + ψ y | y ⟩. Sinusoidal plane-wave solutions of the electromagnetic wave equation Polarization Circular polarization Elliptical polarization Plane of polarization Photon polarization Jackson, John D.. Classical Electrodynamics. Wiley. ISBN 0-471-30932-X. Animation of Linear Polarization Comparison of Linear Polarization with Circular and Elliptical Polarizations This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C"
Hydrolysis is a term used for both an electro-chemical process and a biological one. The hydrolysis of water is the separation of water molecules into hydrogen and oxygen atoms using electricity. Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts; when a carbohydrate is broken into its component sugar molecules by hydrolysis, this is termed saccharification. Hydrolysis or saccharification is a step in the degradation of a substance. Hydrolysis can be the reverse of a condensation reaction in which two molecules join together into a larger one and eject a water molecule, thus hydrolysis adds water to break down, whereas condensation builds up by removing water and any other solvents. Some hydration reactions are hydrolysis. Hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both water molecule to split into two parts. In such reactions, one fragment of the target molecule gains a hydrogen ion.
It breaks a chemical bond in the compound. A common kind of hydrolysis occurs when a salt of weak base is dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations; the salt dissociates into its constituent anions and cations. For example, sodium acetate dissociates in water into acetate ions. Sodium ions react little with the hydroxide ions whereas the acetate ions combine with hydronium ions to produce acetic acid. In this case the net result is a relative excess of hydroxide ions. Strong acids undergo hydrolysis. For example, dissolving sulfuric acid in water is accompanied by hydrolysis to give hydronium and bisulfate, the sulfuric acid's conjugate base. For a more technical discussion of what occurs during such a hydrolysis, see Brønsted–Lowry acid–base theory. Acid–base-catalysed hydrolyses are common, their hydrolysis occurs when the nucleophile attacks the carbon of the carbonyl group of the ester or amide. In an aqueous base, hydroxyl ions are better nucleophiles than polar molecules such as water.
In acids, the carbonyl group becomes protonated, this leads to a much easier nucleophilic attack. The products for both hydrolyses are compounds with carboxylic acid groups; the oldest commercially practiced example of ester hydrolysis is saponification. It is the hydrolysis of a triglyceride with an aqueous base such as sodium hydroxide. During the process, glycerol is formed, the fatty acids react with the base, converting them to salts; these salts are called soaps used in households. In addition, in living systems, most biochemical reactions take place during the catalysis of enzymes; the catalytic action of enzymes allows the hydrolysis of proteins, fats and carbohydrates. As an example, one may consider proteases, they catalyse the hydrolysis of interior peptide bonds in peptide chains, as opposed to exopeptidases. However, proteases do not catalyse the hydrolysis of all kinds of proteins, their action is stereo-selective: Only proteins with a certain tertiary structure are targeted as some kind of orienting force is needed to place the amide group in the proper position for catalysis.
The necessary contacts between an enzyme and its substrates are created because the enzyme folds in such a way as to form a crevice into which the substrate fits. Therefore, proteins that do not fit into the crevice will not undergo hydrolysis; this specificity preserves the integrity of other proteins such as hormones, therefore the biological system continues to function normally. Upon hydrolysis, an amide converts into an amine or ammonia. One of the two oxygen groups on the carboxylic acid are derived from a water molecule and the amine gains the hydrogen ion; the hydrolysis of peptides gives amino acids. Many polyamide polymers such as nylon 6,6 hydrolyse in the presence of strong acids; the process leads to depolymerization. For this reason nylon products fail by fracturing. Polyesters are susceptible to similar polymer degradation reactions; the problem is known as environmental stress cracking. Hydrolysis is related to energy storage. All living cells require a continual supply of energy for two main purposes: the biosynthesis of micro and macromolecules, the active transport of ions and molecules across cell membranes.
The energy derived from the oxidation of nutrients is not used directly but, by means of a complex and long sequence of reactions, it is channelled into a special energy-storage molecule, adenosine triphosphate. The ATP molecule contains pyrophosphate linkages. ATP can undergo hydrolysis in two ways: the removal of terminal phosphate to form adenosine diphosphate and inorganic phosphate, or the removal of a terminal diphosphate to yield adenosine monophosphate and pyrophosphate; the latter undergoes further cleavage in
A mirror image is a reflected duplication of an object that appears identical, but is reversed in the direction perpendicular to the mirror surface. As an optical effect it results from reflection off of substances such as water, it is a concept in geometry and can be used as a conceptualization process for 3-D structures. In geometry, the mirror image of an object or two-dimensional figure is the virtual image formed by reflection in a plane mirror. Two-dimensional mirror images can be seen in the reflections of mirrors or other reflecting surfaces, or on a printed surface seen inside-out. If we look at an object, two-dimensional and turn it towards a mirror, the object turns through an angle of 180º and we see a left-right reversal in the mirror. In this example, it is the change in orientation rather than the mirror itself that causes the observed reversal. Another example is when we stand with our backs to the mirror and face an object that's in front of the mirror. We compare the object with its reflection by turning ourselves 180º, towards the mirror.
Again we perceive a left-right reversal due to a change in orientation. So, in these examples the mirror does not cause the observed reversals; the concept of reflection can be extended to three-dimensional objects, including the inside parts if they are not transparent. The term relates to structural as well as visual aspects. A three-dimensional object is reversed in the direction perpendicular to the mirror surface. In physics, mirror images are investigated in the subject called geometrical optics. In chemistry, two versions of a molecule, one a "mirror image" of the other, are called enantiomers if they are not "superposable" on each other; that is an example of chirality. In general, an object and its mirror image are called enantiomorphs. If a point of an object has coordinates the image of this point has coordinates, thus reflection is a reversal of the coordinate axis perpendicular to the mirror's surface. Although a plane mirror reverses an object only in the direction normal to the mirror surface, there is a perception of a left-right reversal.
Hence, the reversal is called "lateral inversion". The perception of a left-right reversal is because the left and right of an object are defined by its perceived top and front, but there is still some debate about the explanation amongst psychologists; the psychology of the perceived left-right reversal is discussed in "Much ado about mirrors" by Professor Michael Corballis. Reflection in a mirror does result in a change in chirality, more from a right-handed to a left-handed coordinate system; as a consequence, if one looks in a mirror and lets two axes coincide with those in the mirror this gives a reversal of the third axis. If a person stands side-on to a mirror and right will be reversed directly by the mirror, because the person's left-right axis is normal to the mirror plane. However, it's important to understand that there are always only two enantiomorphs, the object and its image. Therefore, no matter how the object is oriented towards the mirror, all the resulting images are fundamentally identical.
In the picture of the mountain reflected in the lake, the reversal normal to the reflecting surface is obvious. Notice that there is no obvious front-back or left-right of the mountain. In the example of the urn and mirror, the urn is symmetrical front-back. Thus, no obvious reversal of any sort can be seen in the mirror image of the urn. A mirror image appears more three-dimensional if the observer moves, or if the image is viewed using binocular vision; this is because the relative position of objects changes as the observer's perspective changes, or is differently viewed with each eye. Looking through a mirror from different positions is like looking at the 3D mirror image of space. A mirror does not just produce an image of. A mirror hanging on the wall makes the room brighter because additional light sources appear in the mirror image. However, the appearance of additional light does not violate the conservation of energy principle, because some light no longer reaches behind the mirror, as the mirror re-directs the light energy.
In terms of the light distribution, the virtual mirror image has the same appearance and the same effect as a real, symmetrically arranged half-space behind a window. Shadows may extend from the mirror into the halfspace before it, vice versa. In mirror writing a text is deliberately displayed in mirror image, in order to be read through a mirror. For example, emergency vehicles such as ambulances or fire engines use mirror images in order to be read from a driver's rear-view mirror; some movie theaters take advantage of mirror writing in a Rear Window Captioning System used to assist individuals with heari
Inverted sugar syrup
Inverted sugar syrup is an edible mixture of two simple sugars—glucose and fructose—that is made by heating sucrose with water. It is thought to be sweeter than table sugar, foods that contain it retain moisture and crystallize less easily. Bakers, who call it invert syrup, may use it more than other sweeteners. Though inverted sugar syrup can be made by heating table sugar in water alone, the reaction can be sped up by adding lemon juice, cream of tartar or other catalysts without changing the flavor noticeably; the mixture of the two simple sugars is formed by a process of hydrolysis of sucrose. This mixture has the opposite direction of optical rotation as the original sugar, why it is called an invert sugar. Table sugar is converted to invert sugar by hydrolysis. Heating a mixture or solution of table sugar and water breaks the chemical bond that links together the two simple-sugar components; the balanced chemical equation for the hydrolysis of sucrose into glucose and fructose is: C12H22O11 + H2O → C6H12O6 + C6H12O6 Once a sucrose solution has had some of its sucrose turned into glucose and fructose the solution is no longer said to be pure.
The gradual decrease in purity of a sucrose solution as it is hydrolyzed affects a chemical property of the solution called optical rotation that can be used to figure out how much of the sucrose has been hydrolyzed and therefore whether the solution has been inverted or not. A kind of light called plane polarized light can be shone through a sucrose solution as it is heated up for hydrolysis; such light has an ` angle'. When such light is shone through a solution of pure sucrose it comes out the other side with a different angle than when it entered; when the rotation between the angle the light has when it enters and when it exits is in the clockwise direction, the light is said to be'rotated right' and α is given to have a positive angle like 64 degrees. When the rotation between the angle the light has when it enters and when it exits is in the counterclockwise direction, the light is said to be'rotated left' and α is given a negative angle like − 39 degrees; when plane polarized light enters and exits a solution of pure sucrose its angle is rotated 66.5 degrees.
As the sucrose is heated up and hydrolyzed the amount of glucose and fructose in the mixture increases and the optical rotation decreases. After α passes zero and becomes a negative optical rotation, meaning that the rotation between the angle the light has when it enters and when it exits is in the counter clockwise direction, it is said that the optical rotation has'inverted' its direction; this leads to the definition of an'inversion point' as the per cent amount sucrose that has to be hydrolyzed before α equals zero. Any solution which has passed the inversion point is said to be'inverted'; as the shapes of the molecules of sucrose and fructose are all asymmetrical the three sugars come in several different forms, called stereoisomers. The existence of these forms is; when plane polarized light passes through a pure solution of one of these forms of one of the sugars it is thought to hit and'glance off' certain asymmetrical chemical bonds within the molecule of that form of that sugar. Because those particular bonds are different in each form of the sugar, each form rotates the light to a different degree.
When any one form of a sugar is purified and put in water, it takes other forms of the same sugar. This means that a solution of a pure sugar has all of its stereoisomers present in the solution in different amounts which do not change much; this has an'averaging' effect on all of the optical rotation angles of the different forms of the sugar and leads to the pure sugar solution having its own'total' optical rotation, called its'specific rotation' or'observed specific rotation' and, written as. Water molecules do not have chirality, therefore they do not have any effect on the measurement of optical rotation; when plane polarized light enters a body of pure water its angle is no different than. Thus, for water, = 0 degrees. Chemicals that, like water, have specific rotations that equal zero degrees are called'optically inactive' chemicals and like water, they do not need to be considered when calculating optical rotation; the overall optical rotation of a mixture of chemicals can be calculated if the proportion of the amount of each chemical in the solution is known.
If there are N -many optically active different chemicals in a solution and the molar concentration (the number of moles of each chemical per
Inorganic chemistry deals with the synthesis and behavior of inorganic and organometallic compounds. This field covers all chemical compounds except the myriad organic compounds, which are the subjects of organic chemistry; the distinction between the two disciplines is far from absolute, as there is much overlap in the subdiscipline of organometallic chemistry. It has applications in every aspect of the chemical industry, including catalysis, materials science, surfactants, medications and agriculture. Many inorganic compounds are ionic compounds, consisting of cations and anions joined by ionic bonding. Examples of salts are magnesium chloride MgCl2, which consists of magnesium cations Mg2+ and chloride anions Cl−. In any salt, the proportions of the ions are such that the electric charges cancel out, so that the bulk compound is electrically neutral; the ions are described by their oxidation state and their ease of formation can be inferred from the ionization potential or from the electron affinity of the parent elements.
Important classes of inorganic compounds are the oxides, the carbonates, the sulfates, the halides. Many inorganic compounds are characterized by high melting points. Inorganic salts are poor conductors in the solid state. Other important features include their high melting ease of crystallization. Where some salts are soluble in water, others are not; the simplest inorganic reaction is double displacement when in mixing of two salts the ions are swapped without a change in oxidation state. In redox reactions one reactant, the oxidant, lowers its oxidation state and another reactant, the reductant, has its oxidation state increased; the net result is an exchange of electrons. Electron exchange can occur indirectly as well, e.g. in batteries, a key concept in electrochemistry. When one reactant contains hydrogen atoms, a reaction can take place by exchanging protons in acid-base chemistry. In a more general definition, any chemical species capable of binding to electron pairs is called a Lewis acid.
As a refinement of acid-base interactions, the HSAB theory takes into account polarizability and size of ions. Inorganic compounds are found in nature as minerals. Soil may contain iron sulfide as calcium sulfate as gypsum. Inorganic compounds are found multitasking as biomolecules: as electrolytes, in energy storage or in construction; the first important man-made inorganic compound was ammonium nitrate for soil fertilization through the Haber process. Inorganic compounds are synthesized for use as catalysts such as vanadium oxide and titanium chloride, or as reagents in organic chemistry such as lithium aluminium hydride. Subdivisions of inorganic chemistry are organometallic chemistry, cluster chemistry and bioinorganic chemistry; these fields are active areas of research in inorganic chemistry, aimed toward new catalysts and therapies. Inorganic chemistry is a practical area of science. Traditionally, the scale of a nation's economy could be evaluated by their productivity of sulfuric acid.
The top 20 inorganic chemicals manufactured in Canada, Europe, India and the US:Aluminium sulfate, Ammonium nitrate, Ammonium sulfate, Carbon black, hydrochloric acid, hydrogen peroxide, nitric acid, oxygen, phosphoric acid, sodium carbonate, sodium chlorate, sodium hydroxide, sodium silicate, sodium sulfate, sulfuric acid, titanium dioxide. The manufacturing of fertilizers is another practical application of industrial inorganic chemistry. Descriptive inorganic chemistry focuses on the classification of compounds based on their properties; the classification focuses on the position in the periodic table of the heaviest element in the compound by grouping compounds by their structural similarities. When studying inorganic compounds, one encounters parts of the different classes of inorganic chemistry. Different classifications are: Classical coordination compounds feature metals bound to "lone pairs" of electrons residing on the main group atoms of ligands such as H2O, NH3, Cl−, CN−. In modern coordination compounds all organic and inorganic compounds can be used as ligands.
The "metal" is a metal from the groups 3-13, as well as the trans-lanthanides and trans-actinides, but from a certain perspective, all chemical compounds can be described as coordination complexes. The stereochemistry of coordination complexes can be quite rich, as hinted at by Werner's separation of two enantiomers of 6+, an early demonstration that chirality is not inherent to organic compounds. A topical theme within this specialization is supramolecular coordination chemistry. Examples: −, 3+, TiCl42; these species feature elements from groups II, III, IV, V, VI, VII, 0 of the periodic table. Due to their similar reactivity, the elements in group 3 and group 12 are generally included, the lanthanides and actinides are sometimes included as well. Main group compounds have been known since the beginnings of chemistry, e.g. elemental sulfur and the distillable white phosphorus. Experiments on oxygen, O2, by Lavoisier and Priestley not only iden
A crystal or crystalline solid is a solid material whose constituents are arranged in a ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations; the scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification; the word crystal derives from the Ancient Greek word κρύσταλλος, meaning both "ice" and "rock crystal", from κρύος, "icy cold, frost". Examples of large crystals include snowflakes and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Examples of polycrystals include most metals, rocks and ice. A third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever.
Examples of amorphous solids include glass and many plastics. Despite the name, lead crystal, crystal glass, related products are not crystals, but rather types of glass, i.e. amorphous solids. Crystals are used in pseudoscientific practices such as crystal therapy, along with gemstones, are sometimes associated with spellwork in Wiccan beliefs and related religious movements; the scientific definition of a "crystal" is based on the microscopic arrangement of atoms inside it, called the crystal structure. A crystal is a solid where the atoms form a periodic arrangement.. Not all solids are crystals. For example, when liquid water starts freezing, the phase change begins with small ice crystals that grow until they fuse, forming a polycrystalline structure. In the final block of ice, each of the small crystals is a true crystal with a periodic arrangement of atoms, but the whole polycrystal does not have a periodic arrangement of atoms, because the periodic pattern is broken at the grain boundaries.
Most macroscopic inorganic solids are polycrystalline, including all metals, ice, etc. Solids that are neither crystalline nor polycrystalline, such as glass, are called amorphous solids called glassy, vitreous, or noncrystalline; these have no periodic order microscopically. There are distinct differences between crystalline solids and amorphous solids: most notably, the process of forming a glass does not release the latent heat of fusion, but forming a crystal does. A crystal structure is characterized by its unit cell, a small imaginary box containing one or more atoms in a specific spatial arrangement; the unit cells are stacked in three-dimensional space to form the crystal. The symmetry of a crystal is constrained by the requirement that the unit cells stack with no gaps. There are 219 possible crystal symmetries, called crystallographic space groups; these are grouped into 7 crystal systems, such as hexagonal crystal system. Crystals are recognized by their shape, consisting of flat faces with sharp angles.
These shape characteristics are not necessary for a crystal—a crystal is scientifically defined by its microscopic atomic arrangement, not its macroscopic shape—but the characteristic macroscopic shape is present and easy to see. Euhedral crystals are those with well-formed flat faces. Anhedral crystals do not because the crystal is one grain in a polycrystalline solid; the flat faces of a euhedral crystal are oriented in a specific way relative to the underlying atomic arrangement of the crystal: they are planes of low Miller index. This occurs; as a crystal grows, new atoms attach to the rougher and less stable parts of the surface, but less to the flat, stable surfaces. Therefore, the flat surfaces tend to grow larger and smoother, until the whole crystal surface consists of these plane surfaces. One of the oldest techniques in the science of crystallography consists of measuring the three-dimensional orientations of the faces of a crystal, using them to infer the underlying crystal symmetry.
A crystal's habit is its visible external shape. This is determined by the crystal structure, the specific crystal chemistry and bonding, the conditions under which the crystal formed. By volume and weight, the largest concentrations of crystals in the Earth are part of its solid bedrock. Crystals found in rocks range in size from a fraction of a millimetre to several centimetres across, although exceptionally large crystals are found; as of 1999, the world's largest known occurring crystal is a crystal of beryl from Malakialina, Madagascar, 18 m long and 3.5 m in diameter, weighing 380,000 kg. Some crystals have formed by magmatic and metamorphic processes, giving origin to large masses of crystalline rock; the vast majority of igneous rocks are formed from molten magma and the degree of crystallization depends on the conditions under which they solidified. Such rocks as granite, which have cooled slowly and under great pressures, have crystallized.