| Atomic Mass | 178.49u |
|---|---|
| Electron Configuration | [Xe]6s24f145d2 |
| Oxidation States | +4 |
| Year Discovered | 1923 |
What is atomic mass and how is it determined?
The atomic mass of the atom is the mass of the protons plus the mass of the neutrons, 6 + 7, or 13. 3) Weighted Average for All Atoms of an Element The atomic mass of an element is a weighted average of all the element's isotopes based on their natural abundance. It is simple to calculate the atomic mass of an element with these steps.
Where is hafnium found in the world?
Hafnium minerals are very rare. It is chiefly obtained as a by-product of zirconium processing. Hafnium is recovered from zircon, a heavy mineral that accumulates in placer deposits with titanium minerals. Hafnium is produced in Australia, South Africa and the USA.
How do you calculate atomic mass number?
To calculate the numbers of subatomic particles in an atom, use its atomic number and mass number:
- number of protons = atomic number
- number of electrons = atomic number
- number of neutrons = mass number - atomic number
How to calculate the atomic weight?
Locate atomic mass on the periodic table.
- Note that the relative atomic masses listed on the periodic table are average values for the associated element. ...
- Relative atomic masses, as listed on the periodic table, are used to calculate molar masses for atoms and molecules. ...
- For example, the atomic mass of iron is 55.847 amu, which means one mole of iron atoms would weigh 55.847 grams.
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How do u calculate atomic mass?
Together, the number of protons and the number of neutrons determine an element's mass number: mass number = protons + neutrons.
What is the atomic structure of hafnium?
Ruthenium has atomic number of 44, that is, it contains 44 electrons distributed in atomic orbitals and its nucleus has 44 protons and 57 neutrons (Figure 1). Electron distribution in atomic or molecular orbitals is called electron configuration which for Ru and the other group 8 chemical elements is shown in Table 1.
What is hafnium on the periodic table?
The element is number 72 in the periodic table, and is called hafnium. It takes its name from hafnium, the old Latin name for Copenhagen which is the city in which it was first isolated in 1922.
How many electrons and protons does hafnium have?
NameHafniumNumber of Protons72Number of Neutrons106Number of Electrons72Melting Point2150.0° C9 more rows
What element has an atomic number of 24?
Cr ChromiumThe Elements, sorted by Atomic NumberAtomic NumberSymbolName23VVanadium24CrChromium25MnManganese26FeIron76 more rows
What does the atomic mass of an element represent?
The mass number tells us the number the sum of nucleons i.e number of protons and neutrons in the nucleus of an atom. The atomic number is the number of protons found in the nucleus of an atom.
What element has a mass of 72?
The elements of the periodic table sorted by atomic massAtomic MassName chemical elementnumber173.04Ytterbium70174.967Lutetium71178.49Hafnium72180.9479Tantalum73111 more rows
What is the atomic number of hafnium?
72Hafnium / Atomic number
What element has the atomic number of 73?
TantalumTantalum now sits below niobium in the periodic table. It has an atomic number of 73, and an atomic weight of just under 181.
What element has 72 protons and 108 neutrons?
HafniumHafnium is a divine element! Its most abundant isotope, 180Hf contains 72 protons and 108 neutrons (72 = 23 32; 108 = 22 33).
How many electrons does hafnium have?
Hafnium atoms have 72 electrons and the shell structure is 2.8. 18.32.
What element has an atomic mass of 93?
NeptuniumThe elemenents of the periodic table sorted by atomic massAtomic MassName chemical elementnumber237Neptunium93238.0289Uranium92243Americium95244Plutonium94107 more rows
How many protons and neutrons does hafnium have?
72Hafnium / Atomic numberHafnium is a divine element! Its most abundant isotope, 180Hf contains 72 protons and 108 neutrons (72 = 23 32; 108 = 22 33).
How many atoms are in hafnium?
Hafnium is a chemical element with the symbol Hf and atomic number 72.
How many electrons does hafnium have?
Hafnium atoms have 72 electrons and the shell structure is 2.8. 18.32.
What element has the atomic number of 73?
TantalumTantalum now sits below niobium in the periodic table. It has an atomic number of 73, and an atomic weight of just under 181.
What is the mass of Hafnium?
Hafnium is estimated to make up about 5.8 ppm of the Earth 's upper crust by mass. It does not exist as a free element on Earth, but is found combined in solid solution with zirconium in natural zirconium compounds such as zircon, ZrSiO 4, which usually has about 1–4% of the Zr replaced by Hf. Rarely, the Hf/Zr ratio increases during crystallization to give the isostructural mineral hafnon (Hf,Zr)SiO#N#4, with atomic Hf > Zr. An obsolete name for a variety of zircon containing unusually high Hf content is alvite.
What is the chemical name of hafnium?
A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Coster and Hevesy, making it the second-last stable element to be discovered.
What is the oxidation state of hafnium?
Hafnium tends to form inorganic compounds in the oxidation state of +4. Halogens react with it to form hafnium tetrahalides. At higher temperatures, hafnium reacts with oxygen, nitrogen, carbon, boron, sulfur, and silicon. Some compounds of hafnium in lower oxidation states are known.
What is the end product of the separation of hafnium?
About half of all hafnium metal manufactured is produced as a by-product of zirconium refinement. The end product of the separation is hafnium (IV) chloride. The purified hafnium (IV) chloride is converted to the metal by reduction with magnesium or sodium, as in the Kroll process. HfCl 4 + 2 Mg (1100 °C) → 2 MgCl 2 + Hf.
How many isotopes of hafnium are there?
At least 34 isotopes of hafnium have been observed, ranging in mass number from 153 to 186. The five stable isotopes are in the range of 176 to 180. The radioactive isotopes' half-lives range from only 400 ms for 153 Hf, to 2.0 petayears (10 15 years) for the most stable one, 174 Hf.
What is hafnium used for?
Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten .
How does hafnium react with air?
Hafnium reacts in air to form a protective film that inhibits further corrosion. The metal is not readily attacked by acids but can be oxidized with halogens or it can be burnt in air. Like its sister metal zirconium, finely divided hafnium can ignite spontaneously in air. The metal is resistant to concentrated alkalis .
Where is hafnium found?
Hafnium is dispersed in Earth ’s crust to the extent of three parts per million and is invariably found in zirconium minerals up to a few percent compared with zirconium. For example, the minerals zircon, ZrSiO 4 (zirconium orthosilicate), and baddeleyite, which is essentially pure zirconium dioxide, ZrO 2, generally have a hafnium content ...
What number of coordination numbers does hafnium have?
The increased size of the atoms makes the oxides more basic and the aqueous chemistry somewhat more extensive and permits the attainment of coordination numbers 7 and, quite frequently, 8 in a number of hafnium compounds.
What is the preferred method of separating hafnium from zirconium?
Ion-exchange and solvent-extraction techniques have supplanted fractional crystallization and distillation as the preferred methods of separating hafnium from zirconium. In the procedure, crude zirconium tetrachloride is dissolved in an aqueous solution of ammonium thiocyanate, and methyl isobutyl ketone is passed countercurrent to the aqueous mixture, with the result that the hafnium tetrachloride is preferentially extracted. The metal itself is prepared by magnesium reduction of hafnium tetrachloride ( Kroll process, which is also used for titanium) and by the thermal decomposition of tetraiodide (de Boer–van Arkel process).
What is the melting point of tantalum hafnium carbide?
The alloy tantalum hafnium carbide (Ta 4 HfC 5 ), with a melting point of 4,215 °C (7,619 °F), is one of the most refractory substances known. Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now.
How much hafnium is in zirconium?
zirconium: Properties, occurrence, and uses. …zirconium minerals generally have a hafnium content that varies from a few tenths of 1 percent to several percent. For some purposes separation of the two elements is not important: zirconium containing about 1 percent of hafnium is as acceptable as pure zirconium.….
How does hafnium differ from titanium?
The most important respect in which hafnium differs from titanium is that lower oxidation states are of minor importance; there are relatively few compounds of hafnium in other than its tetravalent states. (However, a few trivalent compounds are known.)
What is hafnium used for?
Because of its high neutron-capture cross section and its excellent mechanical properties, hafnium is used for fabricating nuclear-control rods.
Overview
Characteristics
Hafnium is a shiny, silvery, ductile metal that is corrosion-resistant and chemically similar to zirconium (due to its having the same number of valence electrons, being in the same group, but also to relativistic effects; the expected expansion of atomic radii from period 5 to 6 is almost exactly cancelled out by the lanthanide contraction). Hafnium changes from its alpha form, a hexagonal cl…
Production
The heavy mineral sands ore deposits of the titanium ores ilmenite and rutile yield most of the mined zirconium, and therefore also most of the hafnium.
Zirconium is a good nuclear fuel-rod cladding metal, with the desirable properties of a very low neutron capture cross section and good chemical stability at high temperatures. However, because of hafnium's neutron-absorbi…
Chemical compounds
Due to the lanthanide contraction, the ionic radius of hafnium(IV) (0.78 ångström) is almost the same as that of zirconium(IV) (0.79 angstroms). Consequently, compounds of hafnium(IV) and zirconium(IV) have very similar chemical and physical properties. Hafnium and zirconium tend to occur together in nature and the similarity of their ionic radii makes their chemical separation rather difficult. Hafnium tends to form inorganic compounds in the oxidation state of +4. Halogens react …
History
In his report on The Periodic Law of the Chemical Elements, in 1869, Dmitri Mendeleev had implicitly predicted the existence of a heavier analog of titanium and zirconium. At the time of his formulation in 1871, Mendeleev believed that the elements were ordered by their atomic masses and placed lanthanum (element 57) in the spot below zirconium. The exact placement of the element…
Applications
Most of the hafnium produced is used in the manufacture of control rods for nuclear reactors.
Several details contribute to the fact that there are only a few technical uses for hafnium: First, the close similarity between hafnium and zirconium makes it possible to use the more abundant zirconium for most applications; second, h…
Precautions
Care needs to be taken when machining hafnium because it is pyrophoric—fine particles can spontaneously combust when exposed to air. Compounds that contain this metal are rarely encountered by most people. The pure metal is not considered toxic, but hafnium compounds should be handled as if they were toxic because the ionic forms of metals are normally at greatest risk for toxicity, and limited animal testing has been done for hafnium compounds.
See also
• Nuclear isomer – Metastable excited state of a nuclide
• Induced gamma emission
• Zircon – Zirconium silicate, a mineral belonging to the group of nesosilicates