The atomic number (Z) is a term used in chemistry and physics to represent the number of protons found in the nucleus of an atom. In an atom of neutral charge, the number of electrons also equals the atomic number. The atomic number originally meant the number of an element's place in the periodic table. When Mendeleyev arranged the known chemical elements grouped by their similarities in chemistry, it was noticeable that placing them in strict order of atomic mass resulted in some mismatches. Iodine and tellurium ...

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See also:

Effective atomic number, Effective atomic number - For an atom, Effective atomic number - For a compound or mixture

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This section is not meant to be a full description of this problem. For that, see the article on the Hydrogen-like atom, Bohr atom, Schroedinger equation and the Dirac equation. The most widely studied set of quantum numbers is that for a single electron in an atom: not only because it is useful in chemistry, being the basic notion behind the periodic table, valence (chemistry) and a host of other properties, but also because it is a solvable and realis ...

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Quantum number, Quantum number - How many quantum numbers?, Quantum number - Single electron in an atom, Quantum number - Elementary particles

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The most widely studied set of quantum numbers is that for a single electron in an atom: not only because it is useful in chemistry, being the basic notion behind the periodic table, valence (chemistry) and a host of other properties, but also because it is a solvable and realistic problem, and, as such, finds widespread use in textbooks. In non-relativistic quantum mechanics the Hamiltonian of this system consists of the kinetic energy of the electron and the potential energy due to the Coulomb force between the nucleus and the elect ...

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Quantum number, Quantum number - How many quantum numbers?, Quantum number - Single electron in an atom, Quantum number - Elementary particles

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The number of hydrogen atoms in hydrocarbons can be determined, if the number of carbon atoms is known, by using these following equations: Alkanes: CnH2n+2 Alkenes: CnH2n (assuming only one double bond) Alkynes: CnH2n-2 (assuming only one triple bond) Each of these hydrocarbons must follow the 4-hydrogen rule which states that all carbon atoms must have the maximum number of hydrogen atoms ...

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Hydrocarbon, Hydrocarbon - Examples, Hydrocarbon - Three types of hydrocarbons, Hydrocarbon - The number of hydrogen atoms, Hydrocarbon - Molecular graph, Hydrocarbon - Petroleum, Hydrocarbon - Burning Hydrocarbons

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For fission of Uranium-235 the most common radioactive fission products include isotopes of Iodine, Caesium, Strontium, Xenon and Barium. Many of the fission products decay through very shortlived isotopes to form stable isotopes, but also a considerable number of the radioisotopes have half lives longer than a day. Some fission products are useful as beta and gamma sources in medicine and industry, see common beta emitters and commonly used gamma emitting isotopes for more details. Few fission products are alpha particle emitters, but ...

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Fission product, Fission product - Physical process of nuclear fission, Fission product - Mass vs. yield curve, Fission product - FPs in power reactors, Fission product - Fission products listed according to atomic number, Fission product - Krypton, Fission product - Strontium, Fission product - Zirconium, Fission product - Molybdenum, Fission product - Technetium, Fission product - Ruthenium, Fission product - Rhodium, Fission product - Palladium, Fission product - Tellurium-132, Fission product - Iodine, Fission product - Xenon, Fission product - Cesium, Fission product - Barium, Fission product - Lanthanides Lanthanum cerium neodymium and samarium, Fission product - Countermeasures against the worst fission products found in accident fallout, Fission product - Iodine, Fission product - Cesium, Fission product - Strontium, Fission product - Fission products within the back end of the nuclear fuel cycle

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The nucleus of an atom is the very dense region in its center consisting of protons and neutrons. The size of the nucleus is much smaller than the size of the atom itself, and almost all of the mass in an atom is made up from the protons and neutrons with almost no contribution from the electrons. Atomic nucleus - Nuclear Makeup. The nucleus of an atom is made up of very tightly bound protons and neutrons. The electromagnetic force which causes like charges to repel prevents protons from binding together wi ...

Including:

Atomic nucleus - Nuclear Makeup
Atomic nucleus - Isotopes Atomic nucleus - Nuclear Decay Atomic nucleus - Nucleus Size
Atomic nucleus - History Atomic nucleus - Nuclear Fusion Atomic nucleus - Nuclear Fission Atomic nucleus - Production of Heavy Elements Atomic nucleus - Nuclear Physics

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A less formal description of the electrons in atoms can be found at Electron configuration. In quantum mechanics, the state of an atom, i.e. the eigenstates of the atomic Hamiltonian, are expanded (see configuration interaction expansion and basis (linear algebra)) into linear combinations of anti-symmetrized products (Slater determinants) of one-electron functions. The spatial components of these one-electron functions are called atomic orbitals. (When one considers also their spin c ...

Including:

Atomic orbital - Hydrogen-like atoms Atomic orbital - Qualitative characterization
Atomic orbital - Limitations on the quantum numbers Atomic orbital - The shapes of orbitals
Atomic orbital - Orbital energy Atomic orbital - Electron placement and the periodic table Atomic orbital - Related topics

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The simplest atomic orbitals are those that occur in an atom with a single electron, such as the hydrogen atom. In this case the atomic orbitals are the eigenstates of the hydrogen Hamiltonian. They can be obtained analytically (see Hydrogen atom). An atom of any other element ionized down to a single electron is very similar to hydrogen, and the orbitals take the same form. For atoms with two or more electrons, the governing equations can only be solved with the use of methods of iterative approximation. Orbitals of multi-electron at ...

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Atomic orbital, Atomic orbital - From Classical to Quantum, Atomic orbital - Quantum Mechanical Description, Atomic orbital - Hydrogen-like atoms, Atomic orbital - Qualitative characterization, Atomic orbital - Limitations on the quantum numbers, Atomic orbital - The shapes of orbitals, Atomic orbital - Orbital energy, Atomic orbital - Electron placement and the periodic table

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The atomic radius is the distance from the atomic nucleus to the outmost stable electron orbital in an atom that is at equilibrium. It is measured in picometers or angstroms. Atomic radii are called covalent radii (a reference to the types of covalent bonds formed) when referring to non-metallic elements and metallic radii when referring to metals. Technically, the atomic radius is one half of the equilibrium internuclear distance between two adjacent atoms (which may either bonded covalently or present in a close ...

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In chemistry, valence is the power of an atom of an element to combine with other atoms measured by the number of electrons which an atom will give, take, or share to form a chemical bond. This is related to the number of spaces left in an atom's electron shells. The adjective describing an atom's valency uses a Greek prefix such as uni/mono, bi/di, tri, tetra etc. for valencies of 1, 2, 3, 4. Main group elements that are metals generally have only one valency, equal to the number of electrons in the valence shell. Transition ...

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Valence chemistry - List Valence chemistry - External link

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Nucleosynthesis Neutron Capture The R-process The S-process Proton capture: The P-process Alpha decay is a form of radioactive decay in which an atomic nucleus ejects an alpha particle and transforms into a nucleus with mass number 4 less and atomic number 2 less. For example: although this is usually written as: Note that an alpha particle is a helium nucleus, and that both mass number and ato ...

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The simplest atomic orbitals are those that occur in an atom with a single electron, such as the hydrogen atom. In this case the atomic orbitals are the eigenstates of the hydrogen Hamiltonian. They can be obtained analytically (see Hydrogen atom). An atom of any other element ionized down to a single electron is very similar to hydrogen, and the orbitals take the same form. For atoms with two or more electrons, the governing equations can only be solved with the use of methods of iterative approximation. Orbitals of multi-electron at ...

See also:

Atomic orbital, Atomic orbital - Historical Background, Atomic orbital - Formal Quantum Mechanical Definition, Atomic orbital - Hydrogen-like atoms, Atomic orbital - Qualitative characterization, Atomic orbital - Limitations on the quantum numbers, Atomic orbital - The shapes of orbitals, Atomic orbital - Orbital energy, Atomic orbital - Electron placement and the periodic table

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The unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. It is defined to be 1/12 of the mass of one atom of carbon-12. 1 u = 1/NA gram = 1/(1000 NA) kg   (where NA is Avogadro's number) 1 u ≈ 1.66053886 × 10−27 kg See 1 E-27 k ...

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Atomic mass unit - Measuring relative atomic masses Atomic mass unit - History

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Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6. An abundant nonmetallic, tetravalent element, carbon has several allotropic forms: Diamond (hardest known natural mineral). Structure: each atom is bonded tetrahedrally to four others, making a 3-dimensional network of puckered six-membered rings of atoms. Graphite (one of the softest substances). Structure: each atom is bonded trigonally to three other atoms, making a 2-dimensional network of flat s ...

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Carbon - Notable characteristics Carbon - Applications
Carbon - Other uses
Carbon - History and Etymology Carbon - Allotropes Carbon - Occurrence Carbon - Organic compounds
Carbon - Carbon chains
Carbon - Carbon cycle Carbon - Isotopes Carbon - Precautions

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Avogadro's number, also called Avogadro's Constant (NA) is a large constant used in chemistry and physics. Avogadro's number is formally defined as the number of carbon-12 atoms in 12 grams (0.012 kg) of carbon-12, which is approximately 6.023 × 1023. Historically, carbon-12 was chosen as the reference substance because its atomic mass could be measured particularly accurately. A mole is defined as Avogadro's number of particles of any kind of substance (atoms, ions, molecul ...

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Avogadro's number - History Avogadro's number - Application Avogadro's number - Physical significance of Avogadro's number Avogadro's number - Additional physical relations Avogadro's number - Numerical value Avogadro's number - Connection to masses of protons and neutrons Avogadro's number - Avogadro's number in life

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Saturated fat is fat that consists of triglycerides containing only saturated fatty acids. Saturated fatty acids have no double bonds between the carbon atoms of the fatty acid chain (hence, they are fully saturated with hydrogen atoms). There are several kinds of naturally occurring saturated fatty acids, with their only difference being the number of carbon atoms - from 1 to 24. Some common examples of saturated fatty acids are butyric acid with 4 carbon atoms (contained in butter), lauric acid with 12 carbon atoms (contained in mot ...

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Saturated fat - Health issues Saturated fat - Controversy

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46 is the natural number following 45 and preceding 47. << 40 41 42 43 44 45 46 47 48 49 >> List of numbers -- Integers 0 10 20 30 40 50 60 70 80 90 >> 46 number - In mathematics. Forty-six is a Wedderburn-Etherington number, an enneagonal number and a centered triangular number. 46 number - In science. The atomic number of palladium The numbe ...

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46 number - In mathematics 46 number - In science 46 number - In other fields

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The Azimuthal quantum number (or orbital angular momentum quantum number) symbolized as l is a quantum number for an atomic orbital which determines its orbital angular momentum. The azimuthal quantum number is the second of a set of quantum numbers which describe the unique quantum state of an electron and is designated by the letter l. Azimuthal quantum number - Derivation. There are a set of quantum numbers associated with the energy states of the atom. The four quantum numbers n< ...

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Azimuthal quantum number - Derivation Azimuthal quantum number - History

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44 is the natural number following 43 and preceding 45. << 40 41 42 43 44 45 46 47 48 49 >> List of numbers -- Integers 0 10 20 30 40 50 60 70 80 90 >> 44 number - In mathematics. Forty-four is a tribonacci number and an octahedral number. 44 number - In science. The atomic number of ruthenium In astronomy, Messier obj ...

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44 number - In mathematics 44 number - In science 44 number - In other fields

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