What contribution did Moseley Make to the development of the Periodic Table?
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he arranged the periodic table in atomic number by lowest to highest and he is the first one to do that
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Mendeleev is best known for his work on the periodic table\n\nhttp://www.chemistry.co.nz/mendeleev.htm
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The electron as a unit of charge in electrochemistry was posited by G. Johnstone Stoney in 1874, who also coined usage of "electron" in 1894. During the late 1890s a number of physicists posited that electricity could be conceived of as being made of discrete units, which were given a variety of names, but their reality had not been confirmed in a compelling way.\n\nThe discovery that the electron was a subatomic particle was made in 1897 by J.J. Thomson at the Cavendish Laboratory at Cambridge University, while he was studying "cathode rays". Influenced by the work of James Clerk Maxwell, and the discovery of the X-ray, he deduced that cathode rays existed and were negatively charged "particles", which he called "corpuscles." He published his discovery in 1897.\n\nThe periodic law states that the chemical properties of elements largely repeat themselves periodically and is the foundation of the periodic table of elements. The law itself was initially explained by the atomic mass of the elements. However, as there were anomalies in the periodic table, efforts were made to find a better explanation for it. In 1913, Henry Moseley introduced the concept of the atomic number and explained the periodic law with the number of protons each element has. In the same year, Niels Bohr showed that electrons are the actual foundation of the table. In 1916, Gilbert Newton Lewis explained the chemical bonding of elements by electronic interactions.
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A number of chemists contributed to the development of the periodic table during the 19th century; however, Mendeleyev Dmitry Ivanovich, a russian chemist,  is regarded as the primary discoverer. His version of the table was the first to accommodate all the known elements and also successfully predicted the existence of several elements that had not yet been discovered. These undiscovered elements included gallium, scandium, and germanium.\n\n\nDuring the writing of his book, Mendeleyev tried to classify the elements according to their chemical properties. In 1869 he published his first version of what became known as the periodic table, in which he demonstrated the periodic law. In 1871 he published an improved version of the periodic table, in which he left gaps for elements that were not yet known. His chart and theories gained increased acceptance when three predicted elements—gallium, germanium, and scandium—were subsequently discovered.
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Mendeleyev.  This was the order he used to prepare his first periodic table.  Later he switched to atomic number.
503241
British chemist, John Newlands had the idea of arranging chemical elements in order of their relative atomic masses and he arranged his elements in columns. However, Russian chemist, Dmitri Mendeleev greatly improved on Newlands' idea and convinced other chemists to use it, so Mendeleev has been credited with the invention of the periodic table. Dmitri Mendeleev came up with his first version of the periodic table in 1864, since then more than 700 versions of the table have been proposed.\n\nNo chemistry textbook, classroom, lecture theatre or research laboratory is complete without a copy of the periodic table of the elements. Since the earliest days of chemistry, attempts have been made to arrange the known elements in ways that revealed similarities between them. However, it required the genius of Mendeleev to see that arranging elements into patterns was not enough; he realised that there was a natural plan in which each element has its allotted place, and this applies not only to the known elements but to some that were still undiscovered. Today we have the so-called long form of the table. This has emerged supreme from well over 100 designs that have been proposed since the time of Mendeleev. With the advantage of hindsight we can now see why this form of the table was bound to succeed.\n\nToday there are 111 elements recognised by IUPAC, and these are usually displayed in the form of a matrix called a periodic table. The term periodic came from the regular occurrence of certain chemical properties in the list of known elements when these are arranged in order of increasing relative mass. The common form, complete with the new group numbers (1-18) were finally agreed by the International Union of Pure Applied Chemistry, IUPAC, in 1985, after years of wrangling. In truly Parkinsonian fashion, this least important of changes has probably consumed the most effort!\n\nSince Antoine Lavoisier first defined a chemical element and drew up a table of 33 of them for his book 'Traité Elémentaire de Chimie' (Treatise on the Chemical Elements) published in 1789, there have been attempts to classify them. Lavoisier himself grouped them into four categories on the basis of their chemical properties: gases, nonmetals, metals and earths. In the first category he listed substances that we now know as oxides but which at the time had defeated all attempts at separation.\n\nThis desire to identify and classify elements continued in chemistry for another 80 years until Mendeleev stumbled upon the correct classification - the periodic table. Today the periodic table is securely based on the properties of atomic number of the nucleus and the electron energy levels which surround it. Both of these concepts postdate Mendeleev by several decades. He, however perceived them indirectly through the related properties of atomic weight and chemical valency and arrived at the periodic table in 1869.\n\nBecause atomic weight, relative atomic mass, is roughly proportional to atomic number, and because valency, which manifests itself in the chemical composition, is based on the outermost electrons of an atom, Mendeleev had chosen the two properties that in his day most nearly reflected the fundamental principles on which the table today is based. Consciously or subconsciously, he arrived at the idea that a table existed with positions that were to be occupied by the elements, rather than the other way round - that the known elements determined the arrangement of the table, as others imagined.\n\nThis being so, Mendeleev then put the 65 elements he knew into his table and at the same time pointed out the many unoccupied positions in the overall scheme. He took the further and much bolder step of predicting the properties of these missing elements. Moreover, the gap in atomic weights between cerium (140) and tantalum (182) suggested to him that a whole period of the table remained to be discovered. Later in the century many of these elements,
699126
There are 118 elements on the Periodic Table.
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Lithium was discovered in the mineral petalite (LiAl(Si2O5)2) by Johann August Arfvedson in 1817. It was first isolated by William Thomas Brande and Sir Humphrey Davy through the electrolysis of lithium oxide (Li2O). Today, larger amounts of the metal are obtained through the electrolysis of lithium chloride (LiCl). Lithium is not found free in nature and makes up only 0.0007% of the earth's crust.
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Euclid of Alexandria, the ancient Greek mathematician and author of the Elements \n\nclick here:http://en.wikipedia.org/wiki/Euclid\nhttp://en.wikipedia.org/wiki/Euclid%27s_Elements
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I dont know who proved that nucleus is the governing centre but the discoverer was Robert Brown... Maybe it was him who also proved its function as he may have studied it further for the reason for its presence.Anyway shall ask someone and try to tell you...
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Look up Alchemy and Chemistry on Wikipedia or a science site.  The table form you are speaking of seems to be like a chronological list which could be put in a "table" or a "chart"\nMake a grid with the left side being the dates.  to the right, use a much larger "box" to include the KEY event of the chemistry activity or discovery.  You would include things like the creation of fire, trying to turn lead or metal to gold (alchemy) creation of gunpowder, discovery of oxygen, theory of the atom from ancient times to recently, the addition of man made "elements" which are the radioactive elements.  This is not the correct order but you should check on each of these.  Try "key moments of chemistry" or something like that on google.  Look at the periodic table or see a description of the elements which make up the table.  Include Mendeleyev (spelled right?) who created the periodic table.  Etc. Etc.\n\nHere you go!  Don't copy it word for word: http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.html
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At the bottom of the perodic table...\n\nThey are technetium (at. no. 43), which was the first element to be synthesized, promethium (at. no. 61), astatine (at. no. 85), francium (at. no. 87), and the transuranium elements (at. no. 93 and beyond in the periodic table). Some of these elements have since been shown to exist in minute amounts in nature, usually as short-lived members of natural radioactive decay series (see radioactivity).\n\nThe synthetic elements through at. no. 100 (fermium) are created by bombarding a heavy element, such as uranium or plutonium, with neutrons or alpha particles. The synthesis of the transfermium elements (elements with at. no. 101 or greater) is accomplished by the fusion of the nuclei of two lighter elements. Elements 101 through 106 were first produced by fusing the nuclei of slightly lighter elements, such as californium, with those of light elements, such as carbon. Elements 107 through 112 were first produced by fusing the nuclei of medium-weight elements, such as bismuth or lead, with those of other medium-weight elements, such as iron, nickel, or zinc. Element 114 was first produced by fusing the nuclei of plutonium and calcium and subsequently by fusing the nuclei of lead and krypton, as was element 116. Element 115 was produced by bombarding americium with calcium, and element 113 resulted from the radioactive decay of element 115. The claim by Lawrence Berkeley National Laboratory to have created element 118 has been retracted.)\n\nThe transfermium elements are produced in very small quantities (one atom at a time), and identification is therefore very difficult because of half-lives ranging from minutes to milliseconds and the need to identify the products by methods other than known chemical separations. This has led to controversy over reported discoveries and over the naming of the elements. It has been predicted that one isotope of element 114—containing 114 protons and 184 neutrons—would be very stable because its nucleus would have a full complement of protons and neutrons. Termed an “island of stability,” its half-life might be measured in years. However, none of the three isotopes of element 114 synthesized as yet have as many as 184 neutrons, and their half-lives are still in the millisecond range.
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I'm guessing by 'the atomic model' of the atom, you mean the correct model. It was proposed by bohr, and is essentially the same as the rutherford model except that the electrons are held into shells. Note the wikipedia article below.\nas for the reactivity of different groups, you need to read about valence electrons. They're the number of electrons in the incomplete (outermost) electron shell -- group 1 has 1 valence electron, group 17 has one MISSING valence electron. Atoms are more stable when they have 'full' shells, and no incomplete ones, so the group 1 atoms will try to 'give away' their extra electron, while the group 17 atom will try and 'take away' one more electron to complete its shell.
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Yes, you are correct. The atomic number of Molybdenum is 42.
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look up the periodic table...duh
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try here:http://rds.yahoo.com/_ylt=A0oGkjr5altFbCIATYFXNyoA;_ylu=X3oDMTE2aWNrczNxBGNvbG8DdwRsA1dTMQRwb3MDOARzZWMDc3IEdnRpZANERlg1XzMw/SIG=12odtnv12/EXP=1163705465/**http%3a//www.theodoregray.com/PeriodicTable/Elements/013/index.s7.html
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Nobody knows the answer to this exept for Mendeleev himself, and he isn't talking. The first periodic table had 64 elements, although 3 or 4 of those were still purely theoretical. Since there were more than 50 in the first periodic table, you can't really discuss the first 50 added very well. Several models of organization were proposed, but there were around 60 known elements before it was deemed necessary to organize them. Only Mendeleev's used periodicity, and it is the closest to our modern periodic table.\n\nThe only 2 elements in my periodic table are:\n\nWOMANIUM (XX)\nPhysical properties: Generally soft and round in form. Boils at nothing and may freeze any time. Very bitter if not used well.\nChemical properties: Very active and highly unstable. Possesses strong affinity with gold, silver, platinum, and precious stones. Violent when left alone. Turns slightly green when placed next to a better specimen.\nUsage: An extremely good catalyst for dispersion of wealth.\nCaution: Highly explosive in inexperienced hands!\n\nMANIUM (XY)\nPhysical properties: Solid at room temperature but gets bent out of shape easily. Difficult to find a pure sample. Due to rust, aging samples are unable to conduct electricity as easily as young samples.\nChemical properties: Attempts to bond with XX any chance it can get. Also tends to form strong bonds with itself. Becomes explosive when mixed with Childrium for prolonged period of time.\nUsage: Possibly good methane source.\nCaution: In the absence of XX, this element rapidly decomposes and begins to smell.