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

Calculate the difference between the fugacity, Calculate the difference bet...

Calculate the difference between the fugacity? The pressure in a liquid droplet of radius r is greater than the pressure of the surrounding equilibrated gas phase by a quantity

Synthesis of freon and freon synthesis, explain the synthesis of freon and ...

explain the synthesis of freon and westron i need only the synthesis of those coompound

Which is the best reducing agent at 6530 k ? co or c ? , In industries 653k...

In industries 653k is very low temperature so co is the best reducing agent.

Covalent bonding, Covalent Bond Purely electrostatic attractions between...

Covalent Bond Purely electrostatic attractions between ions are nondirectional, but with increasing covalent character the directional properties of valence orbitals become more

Antipyretic - chemistry in action, Antipyretic: Antipyretic is a drug ...

Antipyretic: Antipyretic is a drug that is accountable for lowering the temperature of feverish object. The central nervous system, specifically the hypothalamus, takes an sig

Bromination o vanillin, Ask qwhy is 5-bromovanillin the major productuestio...

Ask qwhy is 5-bromovanillin the major productuestion #Minimum 100 words accepted#

P-block, oxidation state of p-block elements?

oxidation state of p-block elements?

Describe about halide minerals, Q. Describe about Halide Minerals? High...

Q. Describe about Halide Minerals? Highly electropositive alkali and alkaline earth metals tend to form halide salts, which being soluble in water are washed away into the ocea

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