. Group 4 is a of in the. It contains the elements (Ti), (Zr), (Hf) and (Rf). This group lies in the of the periodic table. The group itself has not acquired a; it belongs to the broader grouping of the. The three Group 4 elements that occur naturally are titanium, zirconium and hafnium. The first three members of the group share similar properties; all three are hard under standard conditions.
BWR cores and Zircaloy-4 (both Table I a + b) in PWR cores. However, for a long period of time various problems with fabrication and in-pile. Schemel, ”ASTM manual on Zirconium and Hafnium”, ASTM STP639. Most zirconium minerals contain 1 to 3% hafnium. Hafnium is a ductile metal with a brilliant silver lustre. Manual on Zirconium and Hafnium, STP 639 (1977). On behalf of ASTM we acknowledge with appreciation their. The symbol t indicates increasing stress with in.
However, the fourth element rutherfordium (Rf), has been synthesized in the laboratory; none of its isotopes have been found occurring in nature. All isotopes of rutherfordium are. So far, no experiments in a have been conducted to the next member of the group, unpentoctium (Upo, element 158), and it is unlikely that they will be synthesized in the near future. Contents. Characteristics Chemistry Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells resulting in trends in chemical behavior: 22 titanium 2, 8, 10, 2 40 zirconium 2, 8, 18, 10, 2 72 hafnium 2, 8, 18, 32, 10, 2 104 rutherfordium 2, 8, 18, 32, 32, 10, 2 Most of the chemistry has been observed only for the first three members of the group.
The chemistry of rutherfordium is not very established and therefore the rest of the section deals only with titanium, zirconium, and hafnium. All the elements of the group are reactive metals with a high melting point (1668 °C, 1855 °C, 2233 °C, 2100 °C?). The reactivity is not always obvious due to the rapid formation of a stable oxide layer, which prevents further reactions. The oxides, and are white solids with high melting points and unreactive against most acids. As tetravalent transition metals, all three elements form various, generally in the oxidation state of +4. For the first three metals, it has been shown that they are resistant to concentrated, but react with them to form tetrahalides.
![Zirconium Zirconium](http://upload.wikimedia.org/wikipedia/commons/thumb/0/09/Elemental_abundances.svg/1280px-Elemental_abundances.svg.png)
At higher temperatures, all three metals react with,. Because of the of the elements in the, zirconium and hafnium have nearly identical. The ionic radius of Zr 4+ is 79 and that of Hf 4+ is 78 pm. This similarity results in nearly identical chemical behavior and in the formation of similar chemical compounds. The chemistry of hafnium is so similar to that of zirconium that a separation on chemical reactions was not possible; only the physical properties of the compounds differ. The melting points and boiling points of the compounds and the in solvents are the major differences in the chemistry of these twin elements.
Titanium is considerably different from the other two owing to the effects of the. Physical The table below is a summary of the key physical properties of the group 4 elements. The four question-marked values are extrapolated. Properties of the Group 4 elements Name 1941 K (1668 °C) 2130 K (1857 °C) 2506 K (2233 °C) 2400 K (2100 °C)?
3560 K (3287 °C) 4682 K (4409 °C) 4876 K (4603 °C) 5800 K (5500 °C)? 4.507 gcm −3 6.511 gcm −3 13.31 gcm −3 23.2 gcm −3? Appearance silver metallic silver white silver gray?
140 pm 155 pm 155 pm 150 pm? This section needs expansion. You can help. ( February 2012) Klaproth also discovered zirconium in the mineral in 1789 and named it after the already known Zirkonerde. Hafnium Hafnium had been predicted by in 1869 and measured in 1914 the by to be 72, placing it between the already known elements.
And were the first to search for the new element in zirconium ores. Hafnium was discovered by the two in 1923 in, Denmark, validating the original 1869 prediction of Mendeleev. There has been some controversy surrounding the discovery of hafnium and the extent to which Coster and Hevesy were guided by Bohr's prediction that hafnium would be a transition metal rather than a rare earth element. While titanium and zirconium, as relatively abundant elements, were discovered in the late 18th century, it took until 1923 for hafnium to be identified. This was only partly due to hafnium's relative scarcity. The chemical similarity between zirconium and hafnium made a separation difficult and, without knowing what to look for, hafnium was left undiscovered, although all samples of zirconium, and all of its compounds, used by chemists for over two centuries contained significant amounts of hafnium. Rutherfordium Rutherfordium was reportedly in 1966 at the at (then in the ).
Researchers there bombarded 242 with accelerated 22 and separated the reaction products by gradient thermochromatography after conversion to chlorides by interaction with. 242 94Pu + 22 10Ne → 264− x 104Rf → 264− x 104Rf Cl 4 Production The production of the metals itself is difficult due to their reactivity.
The formation of, and must be avoided to yield workable metals; this is normally achieved by the. The oxides (MO 2) are reacted with and to form the chlorides (MCl 4). The chlorides of the metals are then reacted with magnesium, yielding and the metals. Further purification is done by a developed.
In a closed vessel, the metal reacts with at temperatures above 500 °C forming metal(IV) iodide; at a tungsten filament of nearly 2000 °C the reverse reaction happens and the iodine and metal are set free. The metal forms a solid coating on the tungsten filament and the iodine can react with additional metal resulting in a steady turnover. M + 2 I 2 (low temp.) → MI 4 MI 4 (high temp.) → M + 2 I 2 Occurrence. Heavy minerals (dark) in a quartz beach sand (, India). If the is compared for titanium, zirconium and hafnium, the abundance decreases with increase of atomic mass. Titanium is the seventh most abundant metal in Earth's crust and has an abundance of 6320 ppm, while zirconium has an abundance of 162 ppm and hafnium has only an abundance of 3 ppm. All three stable elements occur in, which are formed, most usually in environments, by concentration due to the of the mineral grains of erosion material from.
The titanium minerals are mostly and, and zirconium occurs in the mineral. Because of the chemical similarity, up to 5% of the zirconium in zircon is replaced by hafnium. The largest producers of the group 4 elements are,. Applications Titanium metal and its alloys have a wide range of applications, where the corrosion resistance, the heat stability and the low density (light weight) are of benefit.
The foremost use of corrosion-resistant hafnium and zirconium has been in nuclear reactors. Zirconium has a very low and hafnium has a high. Therefore, zirconium (mostly as ) is used as of in, while hafnium is used in s for, because each hafnium atom can absorb multiple neutrons.
Smaller amounts of hafnium and zirconium are used in super alloys to improve the properties of those alloys. Biological occurrences The group 4 elements are not known to be involved in the biological chemistry of any living systems. They are hard refractory metals with low aqueous solubility and low availability to the biosphere. Titanium is one of the few first row d-block transition metals with no known biological role. Rutherfordium's radioactivity would make it toxic to living cells. Precautions Titanium is non-toxic even in large doses and does not play any natural role inside the.
Zirconium powder can cause irritation, but only contact with the eyes requires medical attention. OSHA recommendations for zirconium are 5 mg/m 3 limit and a 10 mg/m 3 short-term exposure limit. Only limited data exists on the toxicology of hafnium.
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