Non-metals - hydrogen, Chemistry

Assignment Help:

 

HYDROGEN

Hydrogen is the natural element in the Universe and is a major constituent of stars. It is relatively much less common on Earth but nevertheless forms nearly 1% by mass of the oceans and crust, principally as water and in hydroxide and hydrates minerals of the crust.

The dihydrogen molecule H2 is the stable form of the element under simple conditions, although atomic hydrogen may be made in the gas phase at high temperatures, and hydrogen may convert a metallic liquid or solid at extremely high pressures. At 1 bar pressure, dihydrogen condenses to a liquid at 20 K and solidifies at 14 K, these being the minimum boiling and melting points for any substance except helium. The H-H bond has a dissociation enthalpy of 436 kJ mol-1 and a length of 74 pm. That is the shortest bond known, and one of the strongest single covalent bonds.

Although it is thermodynamically capable of reacting with many compounds and elements, these reactions usually have a large kinetic barrier and needs elevated temperatures and/or the use of catalysts.

 

Hydrides of metals

 

Not every metallic elements form hydrides. Those that do will be classified as follows.

 

  • Highly electropositive metals have solid hydrides regarded as containing the H- ion. They have structures same to halides, although the ionic character of hydrides is undoubtedly much lower. As like LiH (rocksalt structure) and MgH2 (rutile structure ;).

 

  • Some f- and d- block elements form hydrides that are often metallic in nature, and of variable (nonstoichiometric) composition. As like TiH2 and CeH2+x.

 

  • Some heavier p-block metals form molecular hydrides similar to those of nonmetals in the same group, stannane (SnH4) being and digallane (Ga2H6), both of very low stability.

 

 


Related Discussions:- Non-metals - hydrogen

Determine the term - photolithography, Determine the term - Photolithograph...

Determine the term - Photolithography  As used in manufacture of I.C.S, it is the process of transferring geometrical shapes on a mask to surface of a silicon wafer. Photomask

Safety in preparation of preparation of trimethyl, Safety in Preparation of...

Safety in Preparation of Preparation of trimethyl: 1 Use a round-bottomed flask equipped with a Claisen head (lagged with glass-wool), Quickfit thermometer (very expensive!)

Isotopes, Atoms with the different numbers of neutrons and same atomic numb...

Atoms with the different numbers of neutrons and same atomic number are known as isotopes. The chemical properties of an element are determined by wildly the charge on the nucleus,

Resonance, what are the applications of resonance effect

what are the applications of resonance effect

Afbau principle, why exception is seen in lanthanoids

why exception is seen in lanthanoids

Why nichrome and not copper is used as heating element, Explain why nichrom...

Explain why nichrome and not copper is used as heating element whereas manganin is used as standard resistance? For heating elements, primary requirements are high melting poin

Define matrix of the mitochondrion., Write down the complete names and the ...

Write down the complete names and the commonly used abbreviations of the molecules A and B. a) Illustrate the line bond structures of the reactive moieties of these molecules i

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd