# romanian english dictionary book

The chemical symbol for Thorium is Th. E. Discoverer: De Marignac, Charles Galissard, Discoverer: De Marignac, Jean Charles Galissard, Discoverer: Göhring, Otto and Fajans, Kasimir. The mass number in Helium represents how much space a single helium atom takes up (not including electrons, because electrons can be bonded, and my come and go) Chlorine is a yellow-green gas at room temperature. Osmium is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Tin is a post-transition metal in group 14 of the periodic table. The chemical symbol for Lithium is Li. Lv 4. Nitrogen is a chemical element with atomic number 7 which means there are 7 protons and 7 electrons in the atomic structure. The chemical symbol for Tellurium is Te. $\endgroup$ – J. Ari Nov 27 at 16:20 Its physical and chemical properties are most similar to its heavier homologues strontium and barium. Neutrons stabilize the nucleus, because they attract each other and protons , which helps offset the electrical repulsion between protons. Strontium is a chemical element with atomic number 38 which means there are 38 protons and 38 electrons in the atomic structure. Oxygen is a chemical element with atomic number 8 which means there are 8 protons and 8 electrons in the atomic structure. Nuclear stability is a concept that helps to identify the stability of an isotope. There are two electrons which rotate around the nucleus of helium. Francium is the second-least electronegative element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3. Also known as: Helium, gas. The chemical symbol for Germanium is Ge. Chemically, indium is similar to gallium and thallium. Atomic number is the number of protons in the atom of an element and it identifies the element. Rhodium is a rare, silvery-white, hard, corrosion resistant and chemically inert transition metal. Holmium is a chemical element with atomic number 67 which means there are 67 protons and 67 electrons in the atomic structure. Polonium is a rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, including rapid oxidation in air. Americium is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was named after the Americas. The chemical symbol for Copper is Cu. In nuclear industry gadolinium is commonly used as a neutron absorber due to very high neutron absorbtion cross-section of two isotopes 155Gd and 157Gd. Einsteinium is the seventh transuranic element, and an actinide. The chemical symbol for Mercury is Hg. Curium is a hard, dense, silvery metal with a relatively high melting point and boiling point for an actinide. The chemical symbol for Tungsten is W. Tungsten is a rare metal found naturally on Earth almost exclusively in chemical compounds. Helium is a commonly used carrier gas for gas chromatography. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. [170] Since then two adults asphyxiated in South Florida in 2006,[170][171][176] and there were cases in 2009 and 2010, one a Californian youth who was found with a bag over his head, attached to a helium tank,[177] and another teenager in Northern Ireland died of asphyxiation. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. The speed of sound in helium is nearly three times the speed of sound in air. Aluminium is a silvery-white, soft, nonmagnetic, ductile metal in the boron group. The chemical symbol for Lutetium is Lu. Radon occurs naturally as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead. Gold is a chemical element with atomic number 79 which means there are 79 protons and 79 electrons in the atomic structure. The chemical symbol for Lanthanum is La. Lawrencium is a chemical element with atomic number 103 which means there are 103 protons and 103 electrons in the atomic structure. Sodium is a chemical element with atomic number 11 which means there are 11 protons and 11 electrons in the atomic structure. Pure radium is silvery-white alkaline earth metal. In nuclear industry, especially artificial xenon 135 has a tremendous impact on the operation of a nuclear reactor. The chemical symbol for Chlorine is Cl. What is the mass in grams of 1 atom: 4.0026 /(6.022*10^23) = 6.6*10^-24g which is choice 4) above. The chemical symbol for Americium is Am. Hence its mass number is four (the total number protons and neutrons, collectively called nucleons). Naturally occurring potassium is composed of three isotopes, of which 40K is radioactive. 4 years ago. Its atomic number is 2, so it has two protons in its nucleus. Beryllium is a chemical element with atomic number 4 which means there are 4 protons and 4 electrons in the atomic structure. The chemical symbol for Iridium is Ir. Indium is a post-transition metal that makes up 0.21 parts per million of the Earth’s crust. Choose from 500 different sets of mass number flashcards on Quizlet. Mass numbers of typical isotopes of Helium are 3; 4. Dysprosium is used for its high thermal neutron absorption cross-section in making control rods in nuclear reactors, for its high magnetic susceptibility in data storage applications. The chemical symbol for Lead is Pb. Natural boron consists primarily of two stable isotopes, 11B (80.1%) and 10B (19.9%). Fermium is a member of the actinide series. Europium is a chemical element with atomic number 63 which means there are 63 protons and 63 electrons in the atomic structure. The mass number of an atom is equal to the sum of protons and neutrons in the nucleus. A freshly exposed surface of pure copper has a reddish-orange color. Erbium is a chemical element with atomic number 68 which means there are 68 protons and 68 electrons in the atomic structure. Gallium is a chemical element with atomic number 31 which means there are 31 protons and 31 electrons in the atomic structure. if the gases are allowed to mix together, what is the resulting pressure? The atomic mass is the mass of an atom. The metal is found in the Earth’s crust in the pure, free elemental form (“native silver”), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Manganese is a chemical element with atomic number 25 which means there are 25 protons and 25 electrons in the atomic structure. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. The chemical symbol for Sulfur is S. Sulfur is abundant, multivalent, and nonmetallic. It is one of the least reactive chemical elements and is solid under standard conditions. The atomic number of an element is equal to the number of protons in each atom of the element. Learn term:mass number = number of protons plus number of neutrons with free interactive flashcards. The chemical symbol for Vanadium is V. Vanadium is a hard, silvery grey, ductile, and malleable transition metal. Molybdenum a silvery metal with a gray cast, has the sixth-highest melting point of any element. Its nucleus also contains two neutrons. The chemical symbol for Holmium is Ho. This website was founded as a non-profit project, build entirely by a group of nuclear engineers. Helium is a gas element that comes one number two if we find its position in the periodic table of elements. The chemical symbol for Antimony is Sb. This table lists helium isotopes, half-life, and type of decay: Isotope: Half-Life: Decay: He-3: … [89], At high pressures (more than about 20 atm or two MPa), a mixture of helium and oxygen (heliox) can lead to high-pressure nervous syndrome, a sort of reverse-anesthetic effect; adding a small amount of nitrogen to the mixture can alleviate the problem. This example may lead you to believe that atoms have the same number of protons and neutrons, but a further examination of the table above will show that this is not the case. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities. Helium is a non metal element. Tellurium is a brittle, mildly toxic, rare, silver-white metalloid. Because of its closed-shell electron configuration, its density and melting and boiling points differ significantly from those of most other lanthanides. Plutonium is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. Give your answers in kilograms. Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation. The most commonly used spontaneous fission neutron source is the radioactive isotope californium-252. It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Leaving some tolerance for the weight of the balloon and the string, we can approximate that every liter of helium has a lifting force of one gram. Helium-3 atom is the stable isotope of helium with relative atomic mass 3.016029. The chemical symbol for Nickel is Ni. But its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars. He is the symbol of helium, its atomic mass is 4.0 u. read more » Boiling Point » Melting Point » Abundant » State at STP » Discovery Year About Helium . Police have launched an investigation due to a neglect of safety measures. Chromium is a chemical element with atomic number 24 which means there are 24 protons and 24 electrons in the atomic structure. Ah, a single molecule. One atomic mass unit is the mass of a proton, or about $$1.67 \times 10^{-27}$$ kilograms, which is an extremely small mass. The most probable fission fragment masses are around mass 95 (Krypton) and 137 (Barium). Promethium is a chemical element with atomic number 61 which means there are 61 protons and 61 electrons in the atomic structure. Significant concentrations of boron occur on the Earth in compounds known as the borate minerals. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z. After you have that Z value, you can use PV=nRT to determine the number of moles of helium (and therefore mass of helium) needed to take the valve volume (V) up to the test pressure (P) at the testing temperature. The chemical symbol for Cerium is Ce. Its nucleus also contains two neutrons. The chemical symbol for Boron is B. The chemical symbol for Zirconium is Zr. Thorium is commonly found in monazite sands (rare earth metals containing phosphate mineral). Our Website follows all legal requirements to protect your privacy. Atomic mass of Helium is 4.0026 u. The chemical symbol for Promethium is Pm. Also to help understand this concept there is a chart of the nuclides, known as a Segre chart. Silicon is a chemical element with atomic number 14 which means there are 14 protons and 14 electrons in the atomic structure. Berkelium is a chemical element with atomic number 97 which means there are 97 protons and 97 electrons in the atomic structure. Chromium is a steely-grey, lustrous, hard and brittle metal4 which takes a high polish, resists tarnishing, and has a high melting point. 4.00g / mol is the molar mass of helium. As examples of applications, liquid helium is used to cool certain metals to the extremely low temperatures required for superconductivity, such as in superconducting magnets for magnetic resonance imaging. Calcium is an alkaline earth metal, it is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air. We can determine the neutron number of certain isotope. Indium is a chemical element with atomic number 49 which means there are 49 protons and 49 electrons in the atomic structure. The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. Neutron number plus atomic number equals atomic mass number: N+Z=A. The chemical symbol for Barium is Ba. Atomic mass of an element is a fractional quantity . Phosphorus is a chemical element with atomic number 15 which means there are 15 protons and 15 electrons in the atomic structure. For 12C the atomic mass is exactly 12u, since the atomic mass unit is defined from it. 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