See also: Atomic Number – Does it conserve in a nuclear reaction? The chemical symbol for Aluminum is Al. Mass was no longer considered unchangeable in the closed system. Lanthanum is a chemical element with atomic number 57 which means there are 57 protons and 57 electrons in the atomic structure. Francium is found in uranium minerals, and can be made artificially by bombarding thorium with protons. Units of measure have been defined for mass and energy on the atomic scale to make measurements more convenient to express. Discoverer: Davy, Sir H. and Thénard, L.-J. The chemical symbol for Tellurium is Te. Lead is a chemical element with atomic number 82 which means there are 82 protons and 82 electrons in the atomic structure. The chemical symbol for Europium is Eu. Nobelium is the tenth transuranic element and is the penultimate member of the actinide series. The chemical symbol for Iridium is Ir. In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together. Neutron number is rarely written explicitly in nuclide symbol notation, but appears as a subscript to the right of the element symbol. Particle locations in quantum mechanics are not at an exact position, they are described by a probability density function. The chemical symbol for Ruthenium is Ru. Lutetium is a silvery white metal, which resists corrosion in dry air, but not in moist air. These electrons together weigh only a fraction (let say 0.05%) of entire atom. Units of measure have been defined for mass and energy on the atomic scale to make measurements more convenient to express. The commercial use of beryllium requires the use of appropriate dust control equipment and industrial controls at all times because of the toxicity of inhaled beryllium-containing dusts that can cause a chronic life-threatening allergic disease in some people called berylliosis. The chemical symbol for Thulium is Tm. Francium is an alkali metal, that has one valence electron. Yttrium is a chemical element with atomic number 39 which means there are 39 protons and 39 electrons in the atomic structure. In nuclear industry, especially artificial xenon 135 has a tremendous impact on the operation of a nuclear reactor. Titanium is a lustrous transition metal with a silver color, low density, and high strength. Francium is the heaviest of the alkali metals and closely resembles cesium in its chemical properties. It is the most unstable of the first 101 elements. The chemical symbol for Mendelevium is Md. Iridium is a very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium). The unit of measure for mass is the atomic mass unit (amu). The chemical symbol for Boron is B. Under standard conditions, it is the lightest metal and the lightest solid element. Rhenium is a chemical element with atomic number 75 which means there are 75 protons and 75 electrons in the atomic structure. Selenium is a chemical element with atomic number 34 which means there are 34 protons and 34 electrons in the atomic structure. The chemical symbol for Protactinium is Pa. Protactinium is a dense, silvery-gray metal which readily reacts with oxygen, water vapor and inorganic acids. The chemical symbol for Lanthanum is La. Most materials expand when their temperatures increase. Trivial name of Francium is alkali metals*. The chemical symbol for Actinium is Ac. Actinium is a soft, silvery-white radioactive metal. Nitrogen is a chemical element with atomic number 7 which means there are 7 protons and 7 electrons in the atomic structure. Terbium is a silvery-white, rare earth metal that is malleable, ductile, and soft enough to be cut with a knife. The chemical symbol for Iodine is I. Iodine is the heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at standard conditions that sublimes readily to form a violet gas. These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements. Francium… Tantalum is a chemical element with atomic number 73 which means there are 73 protons and 73 electrons in the atomic structure. Sodium is a soft, silvery-white, highly reactive metal. Element 87 of Periodic table is Francium with atomic number 87, atomic weight 223. Francium belongs to alkali group of the periodic table so its physical properties are similar with alkali group elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. Thorium is moderately hard, malleable, and has a high melting point. It is the most electropositive element. Atomic mass (233) g.mol-1. In fact their absorption cross-sections are the highest among all stable isotopes. Elemental sulfur is a bright yellow crystalline solid at room temperature. But its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars. Europium is one of the least abundant elements in the universe. Thulium is the thirteenth and third-last element in the lanthanide series. Francium is formed from the decay of actinium. It may seem, that the space and in fact the matter is empty, but it is not. Ruthenium is a rare transition metal belonging to the platinum group of the periodic table. Caesium is a soft, silvery-gold alkali metal with a melting point of 28.5 °C, which makes it one of only five elemental metals that are liquid at or near room temperature. Mendelevium is a chemical element with atomic number 101 which means there are 101 protons and 101 electrons in the atomic structure. Iodine is a chemical element with atomic number 53 which means there are 53 protons and 53 electrons in the atomic structure. Electronegativity according to Pauling Name: Francium. Like all alkali metals, lithium is highly reactive and flammable, and is stored in mineral oil. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium. The chemical symbol for Nobelium is No. It is even less abundant than the so-called rare earths. Titanium condenser tubes are usually the best technical choice, however titanium is very expensive material. The chemical symbol for Thorium is Th. For example, the neutron number of uranium-238 is 238-92=146. The atomic mass is carried by the atomic nucleus, which occupies only about 10-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. It rarely occurs in its elemental state or as pure ore compounds in the Earth’s crust. The chemical symbol for Vanadium is V. Vanadium is a hard, silvery grey, ductile, and malleable transition metal. al. The chemical symbol for Palladium is Pd. Nickel is a silvery-white lustrous metal with a slight golden tinge. Rising temperatures make the liquid expand in a liquid-in-tube thermometer and bend bimetallic strips. Typical densities of various substances are at atmospheric pressure. Our Website follows all legal requirements to protect your privacy. Number of Neutrons: 136. 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. The chemical symbol for Berkelium is Bk. Praseodymium is a chemical element with atomic number 59 which means there are 59 protons and 59 electrons in the atomic structure. Zirconium is a chemical element with atomic number 40 which means there are 40 protons and 40 electrons in the atomic structure. Bismuth is a chemical element with atomic number 83 which means there are 83 protons and 83 electrons in the atomic structure. Of elements whose most stable isotopes have been identified with certainty, francium is the most unstable. Caesium is a chemical element with atomic number 55 which means there are 55 protons and 55 electrons in the atomic structure. Here are just a few examples of francium’s decay paths: Francium-223 is the element’s longest lived isotope. Titanium is a chemical element with atomic number 22 which means there are 22 protons and 22 electrons in the atomic structure. Discoverer: Marinsky, Jacob A. and Coryell, Charles D. and Glendenin, Lawerence. Density is defined as the mass per unit volume. Mercury is commonly known as quicksilver and was formerly named hydrargyrum. Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm3). Therefore, we cannot determine the neutron number of uranium, for example. See also: Atomic Mass Number – Does it conserve in a nuclear reaction? The various species of atoms whose nuclei contain particular numbers of protons and neutrons are called nuclides. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) stabilizes the free metal somewhat against further oxidation. Assuming spherical shape, the uranium atom have volume of about 26.9 ×10−30 m3. One unified atomic mass unit is approximately the mass of one nucleon (either a single proton or neutron) and is numerically equivalent to 1 g/mol. 2) You may not distribute or commercially exploit the content, especially on another website. For example, 63Cu (29 protons and 34 neutrons) has a mass number of 63 and an isotopic mass in its nuclear ground state is 62.91367 u. The chemical symbol for Chlorine is Cl. The chemical symbol for Magnesium is Mg. Magnesium is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure. It is one of the least reactive chemical elements and is solid under standard conditions. Its melting point is about 27oC and its boiling point is 677oC, but both have uncertainty due to high radioactivity and is extremely rare in nature. For 12C the atomic mass is exactly 12u, since the atomic mas… Only about 5×10−8% of all matter in the universe is europium. Francium is a chemical element with atomic number 87 which means there are 87 protons and 87 electrons in the atomic structure. Cadmium is a soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. There are over 100 different borate minerals, but the most common are: borax, kernite, ulexite etc. It decays into radium-223 through beta decay or into astatine-219 through alpha decay. The standard SI unit is kilograms per cubic meter (kg/m3). Relative atomic mass:-Francium was discovered by Marguerite Perey (FR) in 1939. Pure radium is silvery-white alkaline earth metal. Since nucleons (protons and neutrons) make up most of the mass of ordinary atoms, the density of normal matter tends to be limited by how closely we can pack these nucleons and depends on the internal atomic structure of a substance. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226. 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. Atomic mass of Francium is 223 u. The chemical symbol for Californium is Cf. Terbium is a chemical element with atomic number 65 which means there are 65 protons and 65 electrons in the atomic structure. Aluminum is a chemical element with atomic number 13 which means there are 13 protons and 13 electrons in the atomic structure. It is a noble metal and a member of the platinum group. Rhenium is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. The most commonly used spontaneous fission neutron source is the radioactive isotope californium-252. Melting Point: 27.0 °C (300.15 K, 80.6 °F) Boiling Point: 677.0 °C (950.15 K, 1250.6 °F) Number of Protons/Electrons: 87. The information contained in this website is for general information purposes only. 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. Iodine is the least abundant of the stable halogens, being the sixty-first most abundant element. Platinum is a chemical element with atomic number 78 which means there are 78 protons and 78 electrons in the atomic structure. There are in total 34 isotopes of francium which have mass numbers starting from 199 to 232. Sulfur is a chemical element with atomic number 16 which means there are 16 protons and 16 electrons in the atomic structure. One atomic mass unit is equal to 1.66 x 10-24 grams. In a neutral atom there are as many electrons as protons moving about nucleus. The chemical symbol for Gadolinium is Gd. The chemical symbol for Rhodium is Rh. It is fairly soft and slowly tarnishes in air. The densest material found on earth is the metal osmium, but its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars. Barium is a chemical element with atomic number 56 which means there are 56 protons and 56 electrons in the atomic structure. Europium is a chemical element with atomic number 63 which means there are 63 protons and 63 electrons in the atomic structure. Lead is soft and malleable, and has a relatively low melting point. All of the alkali metals have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge – a cation, which combines with anions to form salts. The chemical symbol for Silicon is Si. Thulium is a chemical element with atomic number 69 which means there are 69 protons and 69 electrons in the atomic structure. Thorium is a chemical element with atomic number 90 which means there are 90 protons and 90 electrons in the atomic structure. Compressibility (also known as the coefficient of compressibility is a measure of the relative volume change of a fluid or solid as a response to a pressure (or mean stress) change. Gadolinium belongs to a rare earth elements (it is one of a set of seventeen chemical elements in the periodic table). The chemical symbol for Holmium is Ho. Chemically, indium is similar to gallium and thallium. Chromium is a steely-grey, lustrous, hard and brittle metal4 which takes a high polish, resists tarnishing, and has a high melting point. The chemical symbol for Cadmium is Cd. The chemical symbol for Mercury is Hg. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z. The atomic radii decrease across the periodic table because as the atomic number increases, the number of protons increases across the period, but the extra electrons are only added to the same quantum shell. Atomic mass of Francium is 223 u. Although classified as a rare earth element, samarium is the 40th most abundant element in the Earth’s crust and is more common than such metals as tin. Actinium is a chemical element with atomic number 89 which means there are 89 protons and 89 electrons in the atomic structure. Lawrencium is a chemical element with atomic number 103 which means there are 103 protons and 103 electrons in the atomic structure. The chemical symbol for Lawrencium is Lr. There are two reasons for the difference between mass number and isotopic mass, known as the mass defect: Note that, it was found the rest mass of an atomic nucleus is measurably smaller than the sum of the rest masses of its constituent protons, neutrons and electrons. For example, 63Cu (29 protons and 34 neutrons) has a mass number of 63 and an isotopic mass in its nuclear ground state is 62.91367 u. Weights of atoms and isotopes are from NIST article. The information contained in this website is for general information purposes only. Xenon is a colorless, dense, odorless noble gas found in the Earth’s atmosphere in trace amounts. The chemical symbol for Bismuth is Bi. The chemical symbol for Ytterbium is Yb. It is by mass the most common element on Earth, forming much of Earth’s outer and inner core. The atomic mass is the mass of an atom. A standard atomic weight cannot be given. All of its isotopes are radioactive. 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. Q. Francium (Fr) has the lowest ionization energy in Group 1 because - answer choices . Sources, facts, uses, scarcity (SRI), podcasts, alchemical symbols, videos and images. We assume no responsibility for consequences which may arise from the use of information from this website. The chemical symbol for Krypton is Kr. Astatine is the rarest naturally occurring element on the Earth’s crust. Atomic number: 87. There are 34 known isotopes of francium ranging in atomic mass from 199 to 232. Atomic Mass Number – Does it conserve in a nuclear reaction? Significant concentrations of boron occur on the Earth in compounds known as the borate minerals. Nearly all technetium is produced synthetically, and only minute amounts are found in the Earth’s crust. chemical properties, health and environmental effects of francium. Hafnium’s large neutron capture cross-section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors. This variation is typically small for solids and liquids but much greater for gases. In nuclear reactors, promethium equilibrium exists in power operation. The chemical symbol for Neon is Ne. Discoverer: Priestley, Joseph and Scheele, Carl Wilhelm, Discoverer: Ramsay, William and Travers, Morris, Discoverer: Ramsay, Sir William and Strutt, John (Lord Rayleigh), Discoverer: Del Rio, Andrés Manuel (1801) and Sefström, Nils Gabriel (1830), Discoverer: Lecoq de Boisbaudran, Paul-Émile, Discoverer: Ramsay, Sir William and Travers, Morris, Discoverer: Bunsen, Robert Wilhelm and Kirchhoff, Gustav Robert, Discoverer: Perrier, Carlo and Segrè, Emilio, Discoverer: Reich, Ferdinand and Richter, Hieronymus, Discoverer: Müller von Reichenstein, Franz Joseph, Discoverer: Ramsay, William and Travers, Morris William, Discoverer: Kirchhoff, Gustav and Bunsen, Robert. Main purpose of this project is to help the public to learn some interesting and important information about chemical elements and many common materials. Cadmium is a chemical element with atomic number 48 which means there are 48 protons and 48 electrons in the atomic structure. Tellurium is chemically related to selenium and sulfur. Einsteinium is a chemical element with atomic number 99 which means there are 99 protons and 99 electrons in the atomic structure. (1 u is equal to 1/12 the mass of one atom of carbon-12) Molar mass (molar weight) is the mass of one mole of a substance and is expressed in g/mol. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. Mass numbers of typical isotopes of Francium are 223. Its valence is +1. Most probably, it is assumed that about 340-550 gms of this metal francium are found in the earth’s crust. The chemical symbol for Indium is In. Atomic Number: 87. Density is defined as the mass per unit volume. The chemical symbol for Helium is He. It can e… The chemical symbol for Tantalum is Ta. It is also sometimes considered the first element of the 6th-period transition metals and is traditionally counted among the rare earth elements. Main purpose of this project is to help the public learn some interesting and important information about chemical elements, ionizing radiation, thermal engineering, reactor physics and nuclear energy. As the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine. Silicon is a chemical element with atomic number 14 which means there are 14 protons and 14 electrons in the atomic structure. The atomic mass is the mass of an atom. For other isotopes, the isotopic mass usually differs and is usually within 0.1 u of the mass number. The atomic mass or relative isotopic mass refers to the mass of a single particle, and therefore is tied to a certain specific isotope of an element. Lead has the highest atomic number of any stable element and concludes three major decay chains of heavier elements. 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. Hafnium is a chemical element with atomic number 72 which means there are 72 protons and 72 electrons in the atomic structure. Its properties are thus intermediate between those of chlorine and iodine. Cobalt is a chemical element with atomic number 27 which means there are 27 protons and 27 electrons in the atomic structure. Praseodymium is the third member of the lanthanide series and is traditionally considered to be one of the rare-earth metals. Consequently, the smallest atom is helium with a radius of 32 pm, while one of the largest is caesium at 225 pm. Radon is a chemical element with atomic number 86 which means there are 86 protons and 86 electrons in the atomic structure. The chemical symbol for Fluorine is F. Fluorine is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. Chemically, sulfur reacts with all elements except for gold, platinum, iridium, tellurium, and the noble gases. The chemical symbol for Niobium is Nb. These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. Atomic Number – Does it conserve in a nuclear reaction? Francium (87) plus the 31 other members in the seventh row puts you at 118, which is the noble gas below Radon. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Atomic Number of Germanium. Discoverer: McMillan, Edwin M. and Abelson, Philip H. Discoverer: Glenn T. Seaborg, Joseph W. Kennedy, Edward M. McMillan, Arthur C. Wohl, Discoverer: Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, Albert Ghiorso, Discoverer: Glenn T. Seaborg, Ralph A. James, Albert Ghiorso, Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street, Jr., Albert Ghiorso, Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Bernard G. Harvey, Gregory R. Choppin, Albert Ghiorso, Discoverer: Albert Ghiorso, Glenn T. Seaborg, Torbørn Sikkeland, John R. Walton, Discoverer: Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, Robert M. Latimer, Copyright 2020 Periodic Table | All Rights Reserved |. Atomic Number: 55 Atomic Mass: 132.9 Number of Protons/Electrons: 55 Number of Neutrons: 78 Classification: Alkali Metals Date of Discovery: 1860 Discoverer: Fustov Kirchoff Uses: removes air traces in vacuum tubes. The chemical symbol for Technetium is Tc. The chemical symbol for Dysprosium is Dy. Oxygen is a colourless, odourless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air. Lawrencium is the final member of the actinide series. Boron is a chemical element with atomic number 5 which means there are 5 protons and 5 electrons in the atomic structure. Our Privacy Policy is a legal statement that explains what kind of information about you we collect, when you visit our Website. 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. Notes on the properties of Francium: Atomic Mass: Atomic mass number given for longest lived isotope. Zirconium is widely used as a cladding for nuclear reactor fuels. The chemical symbol for Copper is Cu. The longest lived isotope, 223 Fr, a daughter of 227 Ac, has a half-life of 22 minutes. Gold is thought to have been produced in supernova nucleosynthesis, from the collision of neutron stars. 1) You may use almost everything for non-commercial and educational use. One atomic mass unit is equal to 1.66 x 10-24 grams. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. The chemical symbol for Yttrium is Y. Yttrium is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a “rare-earth element”. Discoverer: Scientists at Dubna, Russia (1964)/Albert Ghiorso et. The chemical symbol for Astatine is At. The unit of measure for mass is the atomic mass unit (amu). However, this assumes the atom to exhibit a spherical shape, which is only obeyed for atoms in vacuum or free space. The chemical symbol for Polonium is Po. Tin is a post-transition metal in group 14 of the periodic table. In nuclear industry boron is commonly used as a neutron absorber due to the high neutron cross-section of isotope 10B. Berkelium is a member of the actinide and transuranium element series. Thulium is an easily workable metal with a bright silvery-gray luster. The chemical symbol for Phosphorus is P. As an element, phosphorus exists in two major forms—white phosphorus and red phosphorus—but because it is highly reactive, phosphorus is never found as a free element on Earth. Iridium is a chemical element with atomic number 77 which means there are 77 protons and 77 electrons in the atomic structure. Radon occurs naturally as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices. Scandium is a chemical element with atomic number 21 which means there are 21 protons and 21 electrons in the atomic structure. The densest material found on earth is the metal osmium, but its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars. Mendelevium is a metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities. Caesium has physical and chemical properties similar to those of rubidium and potassium. The chemical properties of Francium resemble Cesium, the closest element to Francium, just below it actually, also in the same group/family the Alkali Metals, the most reactive metals in the periodic table. The Van der Waals radius, rw, of an atom is the radius of an imaginary hard sphere representing the distance of closest approach for another atom. Dysprosium is a chemical element with atomic number 66 which means there are 66 protons and 66 electrons in the atomic structure. The atomic mass or relative isotopic mass refers to the mass of a single particle, and therefore is tied to a certain specific isotope of an element. Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm3). Argon is a chemical element with atomic number 18 which means there are 18 protons and 18 electrons in the atomic structure. In some respects zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size. Symbol: Fr. Cerium is a soft, ductile and silvery-white metal that tarnishes when exposed to air, and it is soft enough to be cut with a knife. By mass, aluminium makes up about 8% of the Earth’s crust; it is the third most abundant element after oxygen and silicon and the most abundant metal in the crust, though it is less common in the mantle below. Palladium is a chemical element with atomic number 46 which means there are 46 protons and 46 electrons in the atomic structure. Atomic number. Because of its high chemical reactivity, barium is never found in nature as a free element. It is the electrons that are responsible for the chemical bavavior of atoms, and which identify the various chemical elements. All its isotopes are radioactive and short-lived; its longest-lived isotope, francium-223, has a half-life of 22 minutes. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion-resistant. Francium-223 and francium-221 are the only isotopes that occur in nature, with the former being far more common. Bromine is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured gas. The chemical symbol for Hafnium is Hf. It explains how we use cookies (and other locally stored data technologies), how third-party cookies are used on our Website, and how you can manage your cookie options. For uranium atom, the Van der Waals radius is about 186 pm = 1.86 ×10−10m.