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

Ideal gas is kept inside a container allowed to expand , If an ideal gas is...

If an ideal gas is kept inside a container with movable piston, and is allowed to expand ISOTHERMALLY, then pressure exerted by the gas on the container wall decreses. Why? What h

Explain the modelling for process and recipe, Explain Modelling for process...

Explain Modelling for process and recipe Generally, all problems that appear in food product design can be divided into mixture or process problems, with the latter having th

Entropy generation for the process, Two kg Ammonia (mA) at  P A = 300  kPa...

Two kg Ammonia (mA) at  P A = 300  kPa and T A = -10ºC and 1 kg Ammonia (m B ) at P B = 300 kPa and T B = 100ºC  are mixed in a constant pressure and adiabatic process. Find th

Electrochemical series, Ask question #imum 100 words accepted# Discussion ...

Ask question #imum 100 words accepted# Discussion about electrochemical serirs

Solutions, how to determine the percentage of association or dissociation i...

how to determine the percentage of association or dissociation in a solution?

Aufbau principle is not satisfied, Aufbau principle is not satisfied by: ...

Aufbau principle is not satisfied by: (1) Cr and Cl         (2) Cu and Ag       (3) Cr and Mg     (4) Cu  and Na Ans: Cu and Ag

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

Lactic Acid, What are the physical and chemical properties of lactic acid?

What are the physical and chemical properties of lactic acid?

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