Hafnium and zirconium form nearly identical series of chemical compounds.

Hafnium tends to form inorganic compounds in the oxidation state of + 4.

Hafnium can be alloyed with small amounts of other elements ; e. g. tin and oxygen to increase tensile and creep strength, iron, chromium and niobium for corrosion resistance, and molybdenum for wear resistance, hardness, and machineability.

Hafnium ( ) is a chemical element with the symbol Hf and atomic number 72.

Hafnium is named for Hafnia, the Latin name for " Copenhagen ", where it was discovered.

Hafnium is used in filaments and electrodes.

Hafnium is estimated to make up about 5. 8 ppm of the Earth's upper crust by weight.

Hafnium reserves are projected to last under 10 years if the world population increases and demand grows.

Hafnium ( IV ) chloride and hafnium ( IV ) iodide have some applications in the production and purification of hafnium metal.

Hafnium carbide is the most refractory binary compound known, with a melting point over 3890 ° C, and hafnium nitride is the most refractory of all known metal nitrides, with a melting point of 3310 ° C.

Hafnium Control rods are used to control the operation of the reactor.

Hafnium has excellent properties for reactors using water for both moderation and cooling.

Hafnium diboride is another such new material.

Hafnium carbide is the most refractory binary compound known, with a melting point of 3890 ° C.

This approach is now being used with Hafnium Oxide nanoparticles by nanobiotix.

File: Hf-crystal bar. jpg | Hafnium crystal bar

Hafnium, one of the last stable elements to be discovered, presents an interesting case.

Hafnium absorbs neutrons avidly ( Hf absorbs 600 times more than Zr ), and it can be used in reactor control rods, whereas natural zirconium is practically transparent to neutrons.

* Conflicting Results on a Long-Lived Nuclear Isomer of Hafnium Have Wider Implications This Physics Today article provides a balanced view from 2004.

Coster is known as the co-discoverer of Hafnium ( Hf ) ( element 72 ) in 1923, along with George Charles von Hevesy, by means of X-ray spectroscopic analysis of zirconium ore.

* Chemical & Engineering News article on the history of Hafnium by Eric R. Scerri

Antimony is stable in air at room temperature, but reacts with oxygen if heated to form antimony trioxide, Sb < sub > 2 </ sub > O < sub > 3 </ sub >.

A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation.

Actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation.

In addition to igniting spontaneously in air, it reacts explosively with water even at low temperatures, more so than other members of the first group of the periodic table.

The pigment is absorbed by the wet plaster ; after a number of hours, the plaster dries and reacts with the air: it is this chemical reaction which fixes the pigment particles in the plaster.

When exposed to the atmosphere, zinc reacts with oxygen to form zinc oxide, which further reacts with water molecules in the air to form zinc hydroxide.

However, it reacts with water and rusts readily, and will also burn in air when heated.

* As a reagent in flue-gas desulfurization, it reacts with sulfur dioxide for air pollution control.

The pigment is then absorbed by the wet plaster ; after a number of hours, the plaster dries and reacts with the air: it is this chemical reaction which fixes the pigment particles in the plaster.

Because potassium reacts with water vapor present in the air, it is usually stored under anhydrous mineral oil or kerosene.

The solution reacts with carbon dioxide in the air and precipitates calcium carbonate.

Titanium readily reacts with oxygen at in air, and at in pure oxygen, forming titanium dioxide.

It reacts slowly with cold water and it oxidizes slowly in air.

When UF < sub > 6 </ sub > is exposed to water vapor in the air, it reacts with the moisture to produce UO < sub > 2 </ sub > F < sub > 2 </ sub > ( uranyl fluoride ), a solid, and HF ( hydrogen fluoride ), a gas, both of which are highly soluble and toxic.

When the cement paste exposed to the air and meteoric water reacts with the atmospheric CO < sub > 2 </ sub >, portlandite and the Calcium Silicate Hydrate ( CSH ) of the hardened cement paste become progressively carbonated and the high pH gradually decreases from 13. 5 – 12. 5 to 8. 5, the pH of water in equilibrium with calcite ( calcium carbonate ) and the steel is no longer passivated.

As the base reacts with carbon dioxide ( always present in the air ), the pH drops below 10. 5 and the color disappears.

When released into the air, perc can contribute to smog when it reacts with other volatile organic carbon substances.

The alternating magnetic field produced by the current through the coil reacts against the static magnetic field in turn, causing the coil and attached diaphragm to move the air, thus producing sound.

When Rollo reacts in surprise, Bugsy explains to him that the pheromones he releases into the air attract her.

Titanium when melted reacts with air which creates impurities ; to prevent this, the ingot which would become the fan disk was formed using a " double vacuum " process: the raw materials were melted together in a vacuum, allowed to cool and solidify, then melted in a vacuum once more.

If the tube gets broken, the getter reacts with incoming air leaving a white deposit inside the tube, and it becomes useless ; for this reason, flashed getters are not used in systems which are intended to be opened.

During this period most of the excess calcium hydroxide reacts with the carbon dioxide in the air to form less caustic calcium carbonate ( carbonatation ).

* Nitrogen oxides ( NO < sub > x </ sub >)-Generated when nitrogen in the air reacts with oxygen at the high temperature and pressure inside the engine.