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

Which monomers can undergo free radical, Which monomers can undergo free ra...

Which monomers can undergo free radical, cationic as well as anionic polymerisation with equal ease? CH2=CH2

Explain thiols, Explain thiols Because of the element effect, both thi...

Explain thiols Because of the element effect, both thiols (the compounds with -SH groups) are more acidic than ethanol (CH 3 CH 2 OH). The compound ClCH 2 CH 2 SH is the more

Isomeric alkyl, outline the structure of the isomeric alkyl halides with mo...

outline the structure of the isomeric alkyl halides with molecular formula c4h9cl

Illustrate relative amount of two co-existing phases, Illustrate and demons...

Illustrate and demonstrate that, for correct mass balance, relative amount of two co-existing phases or micro constituents should be as given by lever rule. The lever rule giv

Electrolysis, In electrochemical series moving down the table the ease of ...

In electrochemical series moving down the table the ease of discharge at cathode increases.why? And what is ease of discharge

Calculate the heat flow by a wall - heat conductivity, Heat Conductivity ...

Heat Conductivity When considering the design of houses, the heat conductivity by walls, roofs, and the floor plays an significant role. The heat conductivities (λ) of some bui

Please help me, a 5.00 l reaction vessel contains hydrogen at a partial pre...

a 5.00 l reaction vessel contains hydrogen at a partial pressure of 0.588 atm and oxygen gas at a partial pressure of 0.302 atm.Which element is the limiting reactant in the follow

Describe oxosalts, Q. Describe Oxosalts? In these minerals, metals are ...

Q. Describe Oxosalts? In these minerals, metals are present as their oxosalts, such as carbonates, sulphates, nitrates, phosphates, borates and silicates. Some important minera

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